PickleRick/DESD
1
0
Fork 0
Code Issues 2 Pull Requests Releases Activity

Compare commits

base: PickleRick:6ded9dc0a8cffbc077ec8ab864f94224e0654a55
Branches Tags
PickleRick:main
..
compare: PickleRick:main
Branches Tags
PickleRick:main

11 Commits
6ded9dc0a8 ... main

Author SHA1 Message Date
Davide Cavagnola
dc5ba6c745 Update LAB3/Readme.md 2025-07-13 18:06:10 +02:00
Davide Cavagnola
2da1ff0ea7 Update LAB2/Readme.md 2025-07-13 18:05:10 +02:00
Davide
902163424b feat: Add initial LAB2-3 project presentation and areas for improvement 2025-07-13 18:02:44 +02:00
Davide Cavagnola
1109f8b130 Merge pull request 'Lab 3: Audio Processing System' (#3) from LAB3 into main 2025-06-07 22:18:45 +02:00
Davide
2968db7e3f refactor: Improve code comments and enhance clarity in led_level_controller.vhd 2025-06-03 18:50:58 +02:00
Davide
c4a48db729 refactor: Enhance comments and code clarity in led_level_controller.vhd 2025-06-03 17:18:41 +02:00
Davide
dff2eb439d - update comments 
- add led_level_controller Const
 2025-06-03 14:55:23 +02:00
Davide
79373768fa fix: LFO comments 2025-06-01 18:28:38 +02:00
Davide
9828eed333 fix: Correct LFO step clock cycle calculations for accurate amplitude modulation 2025-06-01 01:03:19 +02:00
Davide
a52023733d refactor: Improve code readability and organization in led_level_controller.vhd 2025-05-31 19:23:45 +02:00
Davide
c66c218f65 Update: 
- LFO <-> LFO_1
- Effect Selector
- modify led_level_controller (1)
 2025-05-31 19:07:49 +02:00
14 changed files with 528 additions and 510 deletions
Expand all files Collapse all files

39
LAB2/Readme.md Normal file
View File

@@ -0,0 +1,39 @@
# LAB2 Project Presentation
## Project Description
The LAB2 project consists of the design and implementation of a digital system for image processing and data communication. The system is composed of several functional blocks, each responsible for a specific task in the processing pipeline. The main objectives are:
- Receive and process image data
- Perform color space conversion (e.g., RGB to grayscale)
- Apply convolution filters to the image
- Packetize the processed data for transmission
- Support loopback and test modes for verification
## Block Diagram
Below is a conceptual block diagram of the LAB2 system:
```mermaid
flowchart LR
IN[PC] -.-> UART[UART]
UART -.-> IN
UART --> DEPACK[Depack]
DEPACK --> C2G[Color to Grayscale Converter]
C2G --> BRAM[BRAM Writer]
BRAM --> Underflow
BRAM -->Overflow
BRAM -->Ok
BRAM <-.-> CONV[Convolution Filter]
BRAM <-.-> CONV
CONV --> PACK[Packetizer]
PACK --> UART
```
## Areas for Improvement
- In loopback mode, when sending an empty packet (FFF1), the module temporarily stores H and F and prepends them to the header of the next packet. There is an error in the pack/depack logic.
- The implementation of the depacketizer is complex, and the precise error has not been identified.
- The color conversion (C2G) uses a divider by 3, but the approximation method is unclear (it sums half of the power-of-two factor used in the divider—why?). -> Just add comments explainig how it works
- Convolution is performed with various unconstrained integers.
- In general, the VHDL code is somewhat complex, although generally correct. Aim to simplify and make the code more readable.

16
LAB3/Readme.md Normal file
View File

@@ -0,0 +1,16 @@
# LAB3 Project Presentation
## Project Description
*To be completed: Add a description of the LAB3 project here.*
## Block Diagram
*To be completed: Add a block diagram of the LAB3 system here (e.g., using Mermaid or an image).*
## Areas for Improvement
- JSTK: Non-atomicity in writing to the RGB LED; the rest is well done and clear.
- Mute: (IF s_axis_tvalid = '1' AND m_axis_tready = '1' THEN) AXIS error; s_axis_tready should be checked. The original would be correct if s_axis_tready was directly connected to m_axis_tready. As written, it waits for ready to assert valid.
- Volume controller: Waits for ready to assert valid (IF s_axis_tvalid = '1' AND m_axis_tready = '1' THEN).
- Balance: (IF s_axis_tvalid = '1' AND m_axis_tready = '1' THEN) AXI condition is incorrect; the rest is correct.

325
LAB3/src/LFO.vhd
View File

@@ -2,16 +2,16 @@ LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL; USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.NUMERIC_STD.ALL; USE IEEE.NUMERIC_STD.ALL;
-- Entity: LFO (Low Frequency Oscillator) -- Entity: LFO (Low Frequency Oscillator) - Alternative Implementation
-- Purpose: Applies tremolo effect to audio by modulating amplitude with a triangular wave -- Purpose: Applies effect to audio by modulating amplitude with a triangular wave
-- Creates classic audio effects like vibrato, tremolo, and amplitude modulation -- This is a simplified, single-process implementation compared to the pipelined version
-- Implements a 3-stage pipeline for efficient real-time audio processing -- Provides real-time audio amplitude modulation for musical effects
ENTITY LFO IS ENTITY LFO IS
GENERIC ( GENERIC (
CHANNEL_LENGHT : INTEGER := 24; -- Bit width of audio samples (24-bit signed) CHANNEL_LENGHT : INTEGER := 24; -- Bit width of audio samples (24-bit signed)
JOYSTICK_LENGHT : INTEGER := 10; -- Bit width of joystick input (10-bit = 0-1023 range) JOYSTICK_LENGHT : INTEGER := 10; -- Bit width of joystick input (10-bit = 0-1023 range)
CLK_PERIOD_NS : INTEGER := 10; -- Clock period in nanoseconds (10ns = 100MHz) CLK_PERIOD_NS : INTEGER := 10; -- Clock period in nanoseconds (10ns = 100MHz)
TRIANGULAR_COUNTER_LENGHT : INTEGER := 10 -- Bit width of triangular wave counter (affects modulation depth) TRIANGULAR_COUNTER_LENGHT : INTEGER := 10 -- Triangular wave counter length (affects modulation depth)
); );
PORT ( PORT (
-- Clock and Reset -- Clock and Reset
@@ -38,219 +38,188 @@ END ENTITY LFO;
ARCHITECTURE Behavioral OF LFO IS ARCHITECTURE Behavioral OF LFO IS
-- Constants for LFO timing configuration -- LFO timing configuration constants
CONSTANT BASE_PERIOD_MICROSECONDS : INTEGER := 1000; -- Base period: 1ms (1kHz base frequency) CONSTANT LFO_COUNTER_BASE_PERIOD_US : INTEGER := 1000; -- Base period: 1ms (1kHz base frequency)
CONSTANT FREQUENCY_ADJUSTMENT_FACTOR : INTEGER := 90; -- Frequency adjustment sensitivity (clock cycles per joystick unit) CONSTANT ADJUSTMENT_FACTOR : INTEGER := 90; -- Frequency adjustment sensitivity (clock cycles per joystick unit)
CONSTANT JOYSTICK_CENTER_VALUE : INTEGER := 2 ** (JOYSTICK_LENGHT - 1); -- Joystick center position (512 for 10-bit) CONSTANT JSTK_CENTER_VALUE : INTEGER := 2 ** (JOYSTICK_LENGHT - 1); -- Joystick center position (512 for 10-bit)
-- Calculate base clock cycles for 1ms period at current clock frequency -- Calculate base clock cycles for 1ms period at current clock frequency
CONSTANT BASE_CLOCK_CYCLES : INTEGER := BASE_PERIOD_MICROSECONDS * 1000 / CLK_PERIOD_NS; CONSTANT LFO_COUNTER_BASE_CLK_CYCLES : INTEGER := LFO_COUNTER_BASE_PERIOD_US * 1000 / CLK_PERIOD_NS; -- 1ms = 100,000 clk cycles
-- Calculate frequency range limits based on joystick range -- Calculate frequency range limits based on joystick range
-- Minimum frequency (fastest LFO): occurs when joystick is at minimum position CONSTANT LFO_CLK_CYCLES_MIN : INTEGER := LFO_COUNTER_BASE_CLK_CYCLES - ADJUSTMENT_FACTOR * (2 ** (JOYSTICK_LENGHT - 1)); -- 53,920 clk cycles (faster)
CONSTANT MIN_CLOCK_CYCLES : INTEGER := BASE_CLOCK_CYCLES - FREQUENCY_ADJUSTMENT_FACTOR * (2 ** (JOYSTICK_LENGHT - 1)); CONSTANT LFO_CLK_CYCLES_MAX : INTEGER := LFO_COUNTER_BASE_CLK_CYCLES + ADJUSTMENT_FACTOR * (2 ** (JOYSTICK_LENGHT - 1) - 1); -- 145,990 clk cycles (slower)
-- Maximum frequency (slowest LFO): occurs when joystick is at maximum position
CONSTANT MAX_CLOCK_CYCLES : INTEGER := BASE_CLOCK_CYCLES + FREQUENCY_ADJUSTMENT_FACTOR * (2 ** (JOYSTICK_LENGHT - 1) - 1);
-- Internal signals for LFO control -- LFO timing control signals
-- Period adjustment based on joystick input (positive = slower, negative = faster) SIGNAL step_clk_cycles_delta : INTEGER RANGE - 2 ** (JOYSTICK_LENGHT - 1) * ADJUSTMENT_FACTOR TO (2 ** (JOYSTICK_LENGHT - 1) - 1) * ADJUSTMENT_FACTOR := 0;
SIGNAL period_adjustment_delta : INTEGER RANGE - 2 ** (JOYSTICK_LENGHT - 1) * FREQUENCY_ADJUSTMENT_FACTOR SIGNAL step_clk_cycles : INTEGER RANGE LFO_CLK_CYCLES_MIN TO LFO_CLK_CYCLES_MAX := LFO_COUNTER_BASE_CLK_CYCLES;
TO (2 ** (JOYSTICK_LENGHT - 1) - 1) * FREQUENCY_ADJUSTMENT_FACTOR := 0; SIGNAL step_counter : NATURAL RANGE 0 TO LFO_CLK_CYCLES_MAX := 0;
SIGNAL current_period_cycles : INTEGER RANGE MIN_CLOCK_CYCLES TO MAX_CLOCK_CYCLES := BASE_CLOCK_CYCLES;
-- Pipeline stage 1 registers - Input processing and period calculation -- Triangular wave generation signals
SIGNAL audio_data_stage1 : STD_LOGIC_VECTOR(CHANNEL_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Registered audio input -- Note: Using signed counter with extra bit to handle full range calculations
SIGNAL enable_flag_stage1 : STD_LOGIC := '0'; -- Registered LFO enable SIGNAL tri_counter : SIGNED(TRIANGULAR_COUNTER_LENGHT DOWNTO 0) := (OTHERS => '0'); -- Triangular wave amplitude
SIGNAL valid_flag_stage1 : STD_LOGIC := '0'; -- Valid data in stage 1 SIGNAL direction_up : STD_LOGIC := '1'; -- Wave direction: '1' = ascending, '0' = descending
SIGNAL last_flag_stage1 : STD_LOGIC := '0'; -- Registered channel indicator
-- Pipeline stage 2 registers - Triangular wave generation -- AXI4-Stream control signals
SIGNAL triangular_wave_value : unsigned(TRIANGULAR_COUNTER_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Current triangular wave amplitude SIGNAL trigger : STD_LOGIC := '0'; -- Trigger to indicate new processed data is ready
SIGNAL wave_direction_up : STD_LOGIC := '1'; -- Triangle wave direction: '1' = ascending, '0' = descending SIGNAL s_axis_tlast_reg : STD_LOGIC := '0'; -- Registered version of tlast for output synchronization
SIGNAL timing_counter : NATURAL RANGE 0 TO MAX_CLOCK_CYCLES := 0; -- Clock cycle counter for LFO timing SIGNAL m_axis_tvalid_int : STD_LOGIC := '0'; -- Internal output valid signal
SIGNAL enable_flag_stage2 : STD_LOGIC := '0'; -- LFO enable flag for stage 2
SIGNAL valid_flag_stage2 : STD_LOGIC := '0'; -- Valid data in stage 2
SIGNAL last_flag_stage2 : STD_LOGIC := '0'; -- Channel indicator for stage 2
SIGNAL audio_data_stage2 : STD_LOGIC_VECTOR(CHANNEL_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Audio data for stage 2
-- Pipeline stage 3 registers - Modulation and output -- Audio processing signal with extended width for multiplication
-- Extended width to accommodate multiplication result before scaling -- Width accommodates: audio sample + triangular counter to prevent overflow
SIGNAL multiplication_result : STD_LOGIC_VECTOR(CHANNEL_LENGHT + TRIANGULAR_COUNTER_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); SIGNAL m_axis_tdata_temp : SIGNED(CHANNEL_LENGHT + TRIANGULAR_COUNTER_LENGHT DOWNTO 0) := (OTHERS => '0');
-- Internal AXI4-Stream control signals
SIGNAL master_valid_internal : STD_LOGIC := '0'; -- Internal output valid signal
SIGNAL slave_ready_internal : STD_LOGIC := '1'; -- Internal input ready signal
BEGIN BEGIN
-- Direct connection: tlast passes through unchanged (maintains channel timing) -- Output signal assignments with proper AXI4-Stream flow control
m_axis_tlast <= last_flag_stage1; m_axis_tvalid <= m_axis_tvalid_int;
-- Input ready logic: Ready when downstream is ready OR no valid data pending, AND not in reset
s_axis_tready <= (m_axis_tready OR NOT m_axis_tvalid_int) AND aresetn;
-- Pipeline stage 1: Input registration and LFO period calculation -- Optimized single process for LFO timing and triangular waveform generation
-- This stage captures input data and calculates the LFO period based on joystick position -- This process handles both the frequency control and wave shape generation
input_processing_stage : PROCESS (aclk) triangular_wave_lfo_generator : PROCESS (aclk)
BEGIN BEGIN
IF rising_edge(aclk) THEN IF rising_edge(aclk) THEN
IF aresetn = '0' THEN IF aresetn = '0' THEN
-- Reset all stage 1 registers to safe initial states -- Reset LFO generator to initial state
audio_data_stage1 <= (OTHERS => '0'); -- Clear audio data step_clk_cycles <= LFO_COUNTER_BASE_CLK_CYCLES; -- Set to base frequency
current_period_cycles <= BASE_CLOCK_CYCLES; -- Set to base frequency step_counter <= 0; -- Clear timing counter
enable_flag_stage1 <= '0'; -- Disable LFO tri_counter <= (OTHERS => '0'); -- Start triangular wave at zero
valid_flag_stage1 <= '0'; -- No valid data direction_up <= '1'; -- Start counting up
last_flag_stage1 <= '0'; -- Clear channel indicator
ELSE ELSE
-- Calculate LFO period based on joystick y-axis input -- Calculate LFO period based on joystick input
-- Joystick mapping: -- Joystick mapping:
-- 0-511: Faster than base frequency (shorter period) -- 0-511: Slower than base frequency (longer period, lower frequency)
-- 512: Base frequency (1kHz) -- 512: Base frequency (1kHz)
-- 513-1023: Slower than base frequency (longer period) -- 513-1023: Faster than base frequency (shorter period, higher frequency)
period_adjustment_delta <= (to_integer(unsigned(lfo_period)) - JOYSTICK_CENTER_VALUE) * FREQUENCY_ADJUSTMENT_FACTOR; step_clk_cycles_delta <= (to_integer(unsigned(lfo_period)) - JSTK_CENTER_VALUE);
current_period_cycles <= BASE_CLOCK_CYCLES - period_adjustment_delta; step_clk_cycles <= LFO_COUNTER_BASE_CLK_CYCLES - step_clk_cycles_delta * ADJUSTMENT_FACTOR;
-- AXI4-Stream handshake: accept new data when both valid and ready
IF s_axis_tvalid = '1' AND slave_ready_internal = '1' THEN
audio_data_stage1 <= s_axis_tdata; -- Register input audio sample
enable_flag_stage1 <= lfo_enable; -- Register enable control
valid_flag_stage1 <= '1'; -- Mark data as valid for next stage
last_flag_stage1 <= s_axis_tlast; -- Register channel boundary signal
ELSE
valid_flag_stage1 <= '0'; -- No valid data to pass to next stage
END IF;
END IF;
END IF;
END PROCESS input_processing_stage;
-- Pipeline stage 2: Triangular wave generation
-- This stage generates the triangular wave that will modulate the audio amplitude
triangular_wave_generator : PROCESS (aclk)
BEGIN
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
-- Reset triangular wave generator to initial state
timing_counter <= 0; -- Clear timing counter
triangular_wave_value <= (OTHERS => '0'); -- Start at zero amplitude
wave_direction_up <= '1'; -- Start counting up
enable_flag_stage2 <= '0'; -- Disable LFO
valid_flag_stage2 <= '0'; -- No valid data
last_flag_stage2 <= '0'; -- Clear channel indicator
audio_data_stage2 <= (OTHERS => '0'); -- Clear audio data
ELSE
-- Pass through pipeline registers from stage 1 to stage 2
enable_flag_stage2 <= enable_flag_stage1; -- Forward enable flag
valid_flag_stage2 <= valid_flag_stage1; -- Forward valid flag
last_flag_stage2 <= last_flag_stage1; -- Forward channel indicator
audio_data_stage2 <= audio_data_stage1; -- Forward audio data
-- Generate triangular wave when LFO is enabled -- Generate triangular wave when LFO is enabled
IF enable_flag_stage1 = '1' THEN IF lfo_enable = '1' THEN
-- Clock divider: update triangular counter based on calculated period
IF timing_counter < current_period_cycles THEN
timing_counter <= timing_counter + 1; -- Count towards period target
ELSE
timing_counter <= 0; -- Reset counter for next period
-- Update triangular wave: count up or down based on current direction -- Clock divider: Update triangular wave at calculated rate
IF step_counter >= step_clk_cycles THEN
step_counter <= 0; -- Reset counter for next period
-- Check for triangular wave direction changes at extremes
-- Note: Using (2^n - 2) and 1 instead of (2^n - 1) and 0 due to process signal assignment
IF tri_counter = (2 ** TRIANGULAR_COUNTER_LENGHT) - 2 THEN
direction_up <= '0'; -- Switch to descending at near-maximum
ELSIF tri_counter = 1 THEN
direction_up <= '1'; -- Switch to ascending at near-minimum
END IF;
-- Update triangular wave value based on current direction
-- This creates the classic triangular waveform shape -- This creates the classic triangular waveform shape
IF wave_direction_up = '1' THEN IF direction_up = '1' THEN
-- Ascending phase: check if we reached maximum amplitude tri_counter <= tri_counter + 1; -- Ascending: increment
IF triangular_wave_value = (2 ** TRIANGULAR_COUNTER_LENGHT) - 1 THEN
wave_direction_up <= '0'; -- Switch to descending phase
triangular_wave_value <= triangular_wave_value - 1; -- Start decreasing
ELSE ELSE
triangular_wave_value <= triangular_wave_value + 1; -- Continue increasing tri_counter <= tri_counter - 1; -- Descending: decrement
END IF; END IF;
ELSE
-- Descending phase: check if we reached minimum amplitude
IF triangular_wave_value = 0 THEN
wave_direction_up <= '1'; -- Switch to ascending phase
triangular_wave_value <= triangular_wave_value + 1; -- Start increasing
ELSE
triangular_wave_value <= triangular_wave_value - 1; -- Continue decreasing
END IF;
END IF;
END IF;
ELSE
-- LFO disabled: reset triangular wave generator to idle state
timing_counter <= 0; -- Clear timing counter
triangular_wave_value <= (OTHERS => '0'); -- Reset to zero amplitude
wave_direction_up <= '1'; -- Reset to ascending direction
END IF;
END IF;
END IF;
END PROCESS triangular_wave_generator;
-- Pipeline stage 3: Audio modulation and output control ELSE
-- This stage applies the LFO effect by multiplying audio samples with the triangular wave step_counter <= step_counter + 1; -- Continue counting towards next update
modulation_and_output : PROCESS (aclk)
END IF;
END IF;
END IF;
END IF;
END PROCESS triangular_wave_lfo_generator;
-- AXI4-Stream handshake logic and audio processing
-- This process handles input/output data flow and applies the LFO modulation
AXIS : PROCESS (aclk)
BEGIN BEGIN
IF rising_edge(aclk) THEN IF rising_edge(aclk) THEN
IF aresetn = '0' THEN IF aresetn = '0' THEN
-- Reset output stage to safe initial state -- Reset AXI4-Stream interface and audio processing
m_axis_tdata <= (OTHERS => '0'); -- Clear output data s_axis_tlast_reg <= '0'; -- Clear registered channel indicator
master_valid_internal <= '0'; -- No valid output m_axis_tdata_temp <= (OTHERS => '0'); -- Clear temporary audio data
slave_ready_internal <= '1'; -- Ready to accept input m_axis_tvalid_int <= '0'; -- No valid output data
m_axis_tlast <= '0'; -- Clear output channel indicator
ELSE ELSE
-- Output flow control: handle backpressure from downstream modules -- Output handshake management:
IF master_valid_internal = '1' AND m_axis_tready = '0' THEN -- Clear valid flag when downstream accepts data
-- Downstream not ready: maintain current output valid state IF m_axis_tready = '1' THEN
-- This implements proper AXI4-Stream backpressure handling m_axis_tvalid_int <= '0';
master_valid_internal <= '1'; END IF;
ELSIF valid_flag_stage2 = '1' THEN
-- New data available from stage 2: apply LFO effect or bypass -- Data output logic: Send processed audio when trigger is active and output is available
IF enable_flag_stage2 = '1' THEN IF trigger = '1' AND (m_axis_tvalid_int = '0' OR m_axis_tready = '1') THEN
-- Apply LFO tremolo effect: multiply audio sample by triangular wave -- Scale down the multiplication result to original audio bit width
-- This creates amplitude modulation (tremolo effect) -- Right shift by TRIANGULAR_COUNTER_LENGHT effectively divides by 2^TRIANGULAR_COUNTER_LENGHT
multiplication_result <= STD_LOGIC_VECTOR( -- This maintains proper audio amplitude after modulation
m_axis_tdata <= STD_LOGIC_VECTOR(
resize( resize(
signed(audio_data_stage2) * signed('0' & triangular_wave_value), shift_right(
multiplication_result'length m_axis_tdata_temp, -- Wide multiplication result
TRIANGULAR_COUNTER_LENGHT -- Scale factor
),
CHANNEL_LENGHT -- Final audio sample width
) )
); );
-- Scale down result by removing lower bits (equivalent to division by 2^TRIANGULAR_COUNTER_LENGHT) m_axis_tlast <= s_axis_tlast_reg; -- Output registered channel indicator
-- This maintains proper audio amplitude range after multiplication
m_axis_tdata <= multiplication_result(multiplication_result'high DOWNTO TRIANGULAR_COUNTER_LENGHT); m_axis_tvalid_int <= '1'; -- Mark output as valid
trigger <= '0'; -- Clear trigger - data has been output
END IF;
-- Data input logic: Process new audio samples when available and output is ready
IF s_axis_tvalid = '1' AND (m_axis_tready = '1' OR m_axis_tvalid_int = '0') THEN
IF lfo_enable = '1' THEN
-- Apply LFO effect: multiply audio sample by triangular wave
-- This creates amplitude modulation (effect)
m_axis_tdata_temp <= signed(s_axis_tdata) * tri_counter;
s_axis_tlast_reg <= s_axis_tlast; -- Register channel indicator
ELSE ELSE
-- LFO disabled: pass audio through unchanged (bypass mode) -- LFO disabled: pass audio through unchanged but maintain bit width
-- This allows seamless switching between effect and clean audio -- Left shift compensates for the right shift that occurs during output
m_axis_tdata <= audio_data_stage2; -- This ensures unity gain when LFO is bypassed
END IF; m_axis_tdata_temp <= shift_left(
master_valid_internal <= '1'; -- Mark output as valid resize(
ELSE signed(s_axis_tdata), -- Convert input to signed
-- No new data available: clear output valid flag m_axis_tdata_temp'length -- Extend to full processing width
master_valid_internal <= '0'; ),
TRIANGULAR_COUNTER_LENGHT -- Compensate for output scaling
);
s_axis_tlast_reg <= s_axis_tlast; -- Register channel indicator
END IF; END IF;
-- AXI4-Stream ready signal management for proper flow control trigger <= '1'; -- Set trigger to indicate new processed data is ready
IF master_valid_internal = '1' AND m_axis_tready = '1' THEN
-- Successful output handshake: ready for new input data
slave_ready_internal <= '1';
ELSIF s_axis_tvalid = '1' AND slave_ready_internal = '1' THEN
-- Accepted new input: not ready until current output is consumed
-- This prevents data loss in the pipeline
slave_ready_internal <= '0';
END IF;
END IF;
END IF;
END PROCESS modulation_and_output;
-- Output signal assignments END IF;
s_axis_tready <= slave_ready_internal; -- Connect internal ready to output port
m_axis_tvalid <= master_valid_internal; -- Connect internal valid to output port
-- LFO Effect Summary: END IF;
-- 1. Stage 1: Calculates LFO frequency based on joystick position
-- 2. Stage 2: Generates triangular wave at calculated frequency END IF;
-- 3. Stage 3: Multiplies audio samples by triangular wave (tremolo effect)
END PROCESS AXIS;
-- LFO Implementation Summary:
-- 1. Generates triangular wave at frequency controlled by joystick input
-- 2. When enabled: multiplies audio samples by triangular wave (multiplier value range from 0 to 1)
-- 3. When disabled: passes audio through unchanged (bypass mode)
-- 4. Uses proper AXI4-Stream handshaking for real-time audio processing
-- --
-- Audio Effect Characteristics: -- Effect Characteristics:
-- - Tremolo: Periodic amplitude modulation creates "shaking" sound
-- - Frequency range: Approximately 0.1Hz to 10Hz (typical for audio LFO) -- - Frequency range: Approximately 0.1Hz to 10Hz (typical for audio LFO)
-- - Modulation depth: Controlled by TRIANGULAR_COUNTER_LENGHT generic -- - Modulation depth: Controlled by TRIANGULAR_COUNTER_LENGHT generic
-- - Waveform: Triangular (linear amplitude changes, smooth transitions)
-- - Bypass capability: Clean audio passthrough when disabled -- - Bypass capability: Clean audio passthrough when disabled
--
-- Pipeline Benefits:
-- - Maintains real-time audio processing with no dropouts
-- - Allows complex calculations without affecting audio timing
-- - Provides proper AXI4-Stream flow control and backpressure handling
END ARCHITECTURE Behavioral; END ARCHITECTURE Behavioral;

307
LAB3/src/LFO_1.vhd
View File

@@ -2,16 +2,16 @@ LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL; USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.NUMERIC_STD.ALL; USE IEEE.NUMERIC_STD.ALL;
-- Entity: LFO_1 (Low Frequency Oscillator) - Alternative Implementation -- Entity: LFO_1 (Low Frequency Oscillator)
-- Purpose: Applies tremolo effect to audio by modulating amplitude with a triangular wave -- Purpose: Applies tremolo effect to audio by modulating amplitude with a triangular wave
-- This is a simplified, single-process implementation compared to the pipelined version -- Creates classic audio effects like vibrato, tremolo, and amplitude modulation
-- Provides real-time audio amplitude modulation for musical effects -- Implements a 3-stage pipeline for efficient real-time audio processing
ENTITY LFO_1 IS ENTITY LFO_1 IS
GENERIC ( GENERIC (
CHANNEL_LENGHT : INTEGER := 24; -- Bit width of audio samples (24-bit signed) CHANNEL_LENGHT : INTEGER := 24; -- Bit width of audio samples (24-bit signed)
JOYSTICK_LENGHT : INTEGER := 10; -- Bit width of joystick input (10-bit = 0-1023 range) JOYSTICK_LENGHT : INTEGER := 10; -- Bit width of joystick input (10-bit = 0-1023 range)
CLK_PERIOD_NS : INTEGER := 10; -- Clock period in nanoseconds (10ns = 100MHz) CLK_PERIOD_NS : INTEGER := 10; -- Clock period in nanoseconds (10ns = 100MHz)
TRIANGULAR_COUNTER_LENGHT : INTEGER := 10 -- Triangular wave counter length (affects modulation depth) TRIANGULAR_COUNTER_LENGHT : INTEGER := 10 -- Bit width of triangular wave counter (affects modulation depth)
); );
PORT ( PORT (
-- Clock and Reset -- Clock and Reset
@@ -38,188 +38,219 @@ END ENTITY LFO_1;
ARCHITECTURE Behavioral OF LFO_1 IS ARCHITECTURE Behavioral OF LFO_1 IS
-- LFO_1 timing configuration constants -- Constants for LFO_1 timing configuration
CONSTANT LFO_1_COUNTER_BASE_PERIOD_US : INTEGER := 1000; -- Base period: 1ms (1kHz base frequency) CONSTANT BASE_PERIOD_MICROSECONDS : INTEGER := 1000; -- Base period: 1ms (1kHz base frequency)
CONSTANT ADJUSTMENT_FACTOR : INTEGER := 90; -- Frequency adjustment sensitivity (clock cycles per joystick unit) CONSTANT FREQUENCY_ADJUSTMENT_FACTOR : INTEGER := 90; -- Frequency adjustment sensitivity (clock cycles per joystick unit)
CONSTANT JSTK_CENTER_VALUE : INTEGER := 2 ** (JOYSTICK_LENGHT - 1); -- Joystick center position (512 for 10-bit) CONSTANT JOYSTICK_CENTER_VALUE : INTEGER := 2 ** (JOYSTICK_LENGHT - 1); -- Joystick center position (512 for 10-bit)
-- Calculate base clock cycles for 1ms period at current clock frequency -- Calculate base clock cycles for 1ms period at current clock frequency
CONSTANT LFO_1_COUNTER_BASE_CLK_CYCLES : INTEGER := LFO_1_COUNTER_BASE_PERIOD_US * 1000 / CLK_PERIOD_NS; -- 1ms = 100,000 clk cycles CONSTANT BASE_CLOCK_CYCLES : INTEGER := BASE_PERIOD_MICROSECONDS * 1000 / CLK_PERIOD_NS;
-- Calculate frequency range limits based on joystick range -- Calculate frequency range limits based on joystick range
CONSTANT LFO_1_CLK_CYCLES_MIN : INTEGER := LFO_1_COUNTER_BASE_CLK_CYCLES - ADJUSTMENT_FACTOR * (2 ** (JOYSTICK_LENGHT - 1)); -- 53,920 clk cycles (faster) -- Minimum frequency (fastest LFO_1): occurs when joystick is at minimum position
CONSTANT LFO_1_CLK_CYCLES_MAX : INTEGER := LFO_1_COUNTER_BASE_CLK_CYCLES + ADJUSTMENT_FACTOR * (2 ** (JOYSTICK_LENGHT - 1) - 1); -- 145,990 clk cycles (slower) CONSTANT MIN_CLOCK_CYCLES : INTEGER := BASE_CLOCK_CYCLES - FREQUENCY_ADJUSTMENT_FACTOR * (2 ** (JOYSTICK_LENGHT - 1));
-- Maximum frequency (slowest LFO_1): occurs when joystick is at maximum position
CONSTANT MAX_CLOCK_CYCLES : INTEGER := BASE_CLOCK_CYCLES + FREQUENCY_ADJUSTMENT_FACTOR * (2 ** (JOYSTICK_LENGHT - 1) - 1);
-- LFO_1 timing control signals -- Internal signals for LFO_1 control
SIGNAL step_clk_cycles_delta : INTEGER RANGE - 2 ** (JOYSTICK_LENGHT - 1) * ADJUSTMENT_FACTOR TO (2 ** (JOYSTICK_LENGHT - 1) - 1) * ADJUSTMENT_FACTOR := 0; -- Period adjustment based on joystick input (positive = slower, negative = faster)
SIGNAL step_clk_cycles : INTEGER RANGE LFO_1_CLK_CYCLES_MIN TO LFO_1_CLK_CYCLES_MAX := LFO_1_COUNTER_BASE_CLK_CYCLES; SIGNAL period_adjustment_delta : INTEGER RANGE - 2 ** (JOYSTICK_LENGHT - 1) * FREQUENCY_ADJUSTMENT_FACTOR
SIGNAL step_counter : NATURAL RANGE 0 TO LFO_1_CLK_CYCLES_MAX := 0; TO (2 ** (JOYSTICK_LENGHT - 1) - 1) * FREQUENCY_ADJUSTMENT_FACTOR := 0;
SIGNAL current_period_cycles : INTEGER RANGE MIN_CLOCK_CYCLES TO MAX_CLOCK_CYCLES := BASE_CLOCK_CYCLES;
-- Triangular wave generation signals -- Pipeline stage 1 registers - Input processing and period calculation
-- Note: Using signed counter with extra bit to handle full range calculations SIGNAL audio_data_stage1 : STD_LOGIC_VECTOR(CHANNEL_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Registered audio input
SIGNAL tri_counter : SIGNED(TRIANGULAR_COUNTER_LENGHT DOWNTO 0) := (OTHERS => '0'); -- Triangular wave amplitude SIGNAL enable_flag_stage1 : STD_LOGIC := '0'; -- Registered LFO_1 enable
SIGNAL direction_up : STD_LOGIC := '1'; -- Wave direction: '1' = ascending, '0' = descending SIGNAL valid_flag_stage1 : STD_LOGIC := '0'; -- Valid data in stage 1
SIGNAL last_flag_stage1 : STD_LOGIC := '0'; -- Registered channel indicator
-- AXI4-Stream control signals -- Pipeline stage 2 registers - Triangular wave generation
SIGNAL trigger : STD_LOGIC := '0'; -- Trigger to indicate new processed data is ready SIGNAL triangular_wave_value : unsigned(TRIANGULAR_COUNTER_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Current triangular wave amplitude
SIGNAL s_axis_tlast_reg : STD_LOGIC := '0'; -- Registered version of tlast for output synchronization SIGNAL wave_direction_up : STD_LOGIC := '1'; -- Triangle wave direction: '1' = ascending, '0' = descending
SIGNAL m_axis_tvalid_int : STD_LOGIC := '0'; -- Internal output valid signal SIGNAL timing_counter : NATURAL RANGE 0 TO MAX_CLOCK_CYCLES := 0; -- Clock cycle counter for LFO_1 timing
SIGNAL enable_flag_stage2 : STD_LOGIC := '0'; -- LFO_1 enable flag for stage 2
SIGNAL valid_flag_stage2 : STD_LOGIC := '0'; -- Valid data in stage 2
SIGNAL last_flag_stage2 : STD_LOGIC := '0'; -- Channel indicator for stage 2
SIGNAL audio_data_stage2 : STD_LOGIC_VECTOR(CHANNEL_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Audio data for stage 2
-- Audio processing signal with extended width for multiplication -- Pipeline stage 3 registers - Modulation and output
-- Width accommodates: audio sample + triangular counter to prevent overflow -- Extended width to accommodate multiplication result before scaling
SIGNAL m_axis_tdata_temp : SIGNED(CHANNEL_LENGHT + TRIANGULAR_COUNTER_LENGHT DOWNTO 0) := (OTHERS => '0'); SIGNAL multiplication_result : STD_LOGIC_VECTOR(CHANNEL_LENGHT + TRIANGULAR_COUNTER_LENGHT - 1 DOWNTO 0) := (OTHERS => '0');
-- Internal AXI4-Stream control signals
SIGNAL master_valid_internal : STD_LOGIC := '0'; -- Internal output valid signal
SIGNAL slave_ready_internal : STD_LOGIC := '1'; -- Internal input ready signal
BEGIN BEGIN
-- Output signal assignments with proper AXI4-Stream flow control -- Direct connection: tlast passes through unchanged (maintains channel timing)
m_axis_tvalid <= m_axis_tvalid_int; m_axis_tlast <= last_flag_stage1;
-- Input ready logic: Ready when downstream is ready OR no valid data pending, AND not in reset
s_axis_tready <= (m_axis_tready OR NOT m_axis_tvalid_int) AND aresetn;
-- Optimized single process for LFO_1 timing and triangular waveform generation -- Pipeline stage 1: Input registration and LFO_1 period calculation
-- This process handles both the frequency control and wave shape generation -- This stage captures input data and calculates the LFO_1 period based on joystick position
triangular_wave_lfo_generator : PROCESS (aclk) input_processing_stage : PROCESS (aclk)
BEGIN BEGIN
IF rising_edge(aclk) THEN IF rising_edge(aclk) THEN
IF aresetn = '0' THEN IF aresetn = '0' THEN
-- Reset LFO_1 generator to initial state -- Reset all stage 1 registers to safe initial states
step_clk_cycles <= LFO_1_COUNTER_BASE_CLK_CYCLES; -- Set to base frequency audio_data_stage1 <= (OTHERS => '0'); -- Clear audio data
step_counter <= 0; -- Clear timing counter current_period_cycles <= BASE_CLOCK_CYCLES; -- Set to base frequency
tri_counter <= (OTHERS => '0'); -- Start triangular wave at zero enable_flag_stage1 <= '0'; -- Disable LFO_1
direction_up <= '1'; -- Start counting up valid_flag_stage1 <= '0'; -- No valid data
last_flag_stage1 <= '0'; -- Clear channel indicator
ELSE ELSE
-- Calculate LFO_1 period based on joystick input -- Calculate LFO_1 period based on joystick y-axis input
-- Joystick mapping: -- Joystick mapping:
-- 0-511: Faster than base frequency (shorter period, higher frequency) -- 0-511: Faster than base frequency (shorter period)
-- 512: Base frequency (1kHz) -- 512: Base frequency (1kHz)
-- 513-1023: Slower than base frequency (longer period, lower frequency) -- 513-1023: Slower than base frequency (longer period)
step_clk_cycles_delta <= (to_integer(unsigned(lfo_period)) - JSTK_CENTER_VALUE) * ADJUSTMENT_FACTOR; period_adjustment_delta <= (to_integer(unsigned(lfo_period)) - JOYSTICK_CENTER_VALUE) * FREQUENCY_ADJUSTMENT_FACTOR;
step_clk_cycles <= LFO_1_COUNTER_BASE_CLK_CYCLES - step_clk_cycles_delta; current_period_cycles <= BASE_CLOCK_CYCLES - period_adjustment_delta;
-- AXI4-Stream handshake: accept new data when both valid and ready
IF s_axis_tvalid = '1' AND slave_ready_internal = '1' THEN
audio_data_stage1 <= s_axis_tdata; -- Register input audio sample
enable_flag_stage1 <= lfo_enable; -- Register enable control
valid_flag_stage1 <= '1'; -- Mark data as valid for next stage
last_flag_stage1 <= s_axis_tlast; -- Register channel boundary signal
ELSE
valid_flag_stage1 <= '0'; -- No valid data to pass to next stage
END IF;
END IF;
END IF;
END PROCESS input_processing_stage;
-- Pipeline stage 2: Triangular wave generation
-- This stage generates the triangular wave that will modulate the audio amplitude
triangular_wave_generator : PROCESS (aclk)
BEGIN
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
-- Reset triangular wave generator to initial state
timing_counter <= 0; -- Clear timing counter
triangular_wave_value <= (OTHERS => '0'); -- Start at zero amplitude
wave_direction_up <= '1'; -- Start counting up
enable_flag_stage2 <= '0'; -- Disable LFO_1
valid_flag_stage2 <= '0'; -- No valid data
last_flag_stage2 <= '0'; -- Clear channel indicator
audio_data_stage2 <= (OTHERS => '0'); -- Clear audio data
ELSE
-- Pass through pipeline registers from stage 1 to stage 2
enable_flag_stage2 <= enable_flag_stage1; -- Forward enable flag
valid_flag_stage2 <= valid_flag_stage1; -- Forward valid flag
last_flag_stage2 <= last_flag_stage1; -- Forward channel indicator
audio_data_stage2 <= audio_data_stage1; -- Forward audio data
-- Generate triangular wave when LFO_1 is enabled -- Generate triangular wave when LFO_1 is enabled
IF lfo_enable = '1' THEN IF enable_flag_stage1 = '1' THEN
-- Clock divider: update triangular counter based on calculated period
IF timing_counter < current_period_cycles THEN
timing_counter <= timing_counter + 1; -- Count towards period target
ELSE
timing_counter <= 0; -- Reset counter for next period
-- Clock divider: Update triangular wave at calculated rate -- Update triangular wave: count up or down based on current direction
IF step_counter >= step_clk_cycles THEN
step_counter <= 0; -- Reset counter for next period
-- Check for triangular wave direction changes at extremes
-- Note: Using (2^n - 2) and 1 instead of (2^n - 1) and 0 to avoid edge cases
IF tri_counter = (2 ** TRIANGULAR_COUNTER_LENGHT) - 2 THEN
direction_up <= '0'; -- Switch to descending at near-maximum
ELSIF tri_counter = 1 THEN
direction_up <= '1'; -- Switch to ascending at near-minimum
END IF;
-- Update triangular wave value based on current direction
-- This creates the classic triangular waveform shape -- This creates the classic triangular waveform shape
IF direction_up = '1' THEN IF wave_direction_up = '1' THEN
tri_counter <= tri_counter + 1; -- Ascending: increment -- Ascending phase: check if we reached maximum amplitude
IF triangular_wave_value = (2 ** TRIANGULAR_COUNTER_LENGHT) - 1 THEN
wave_direction_up <= '0'; -- Switch to descending phase
triangular_wave_value <= triangular_wave_value - 1; -- Start decreasing
ELSE ELSE
tri_counter <= tri_counter - 1; -- Descending: decrement triangular_wave_value <= triangular_wave_value + 1; -- Continue increasing
END IF; END IF;
ELSE ELSE
step_counter <= step_counter + 1; -- Continue counting towards next update -- Descending phase: check if we reached minimum amplitude
IF triangular_wave_value = 0 THEN
wave_direction_up <= '1'; -- Switch to ascending phase
triangular_wave_value <= triangular_wave_value + 1; -- Start increasing
ELSE
triangular_wave_value <= triangular_wave_value - 1; -- Continue decreasing
END IF; END IF;
END IF; END IF;
END IF; END IF;
ELSE
-- LFO_1 disabled: reset triangular wave generator to idle state
timing_counter <= 0; -- Clear timing counter
triangular_wave_value <= (OTHERS => '0'); -- Reset to zero amplitude
wave_direction_up <= '1'; -- Reset to ascending direction
END IF; END IF;
END IF;
END IF;
END PROCESS triangular_wave_generator;
END PROCESS triangular_wave_lfo_generator; -- Pipeline stage 3: Audio modulation and output control
-- This stage applies the LFO_1 effect by multiplying audio samples with the triangular wave
-- AXI4-Stream handshake logic and audio processing modulation_and_output : PROCESS (aclk)
-- This process handles input/output data flow and applies the LFO_1 modulation
AXIS : PROCESS (aclk)
BEGIN BEGIN
IF rising_edge(aclk) THEN IF rising_edge(aclk) THEN
IF aresetn = '0' THEN IF aresetn = '0' THEN
-- Reset AXI4-Stream interface and audio processing -- Reset output stage to safe initial state
s_axis_tlast_reg <= '0'; -- Clear registered channel indicator m_axis_tdata <= (OTHERS => '0'); -- Clear output data
m_axis_tdata_temp <= (OTHERS => '0'); -- Clear temporary audio data master_valid_internal <= '0'; -- No valid output
m_axis_tvalid_int <= '0'; -- No valid output data slave_ready_internal <= '1'; -- Ready to accept input
m_axis_tlast <= '0'; -- Clear output channel indicator
ELSE ELSE
-- Output handshake management: -- Output flow control: handle backpressure from downstream modules
-- Clear valid flag when downstream accepts data IF master_valid_internal = '1' AND m_axis_tready = '0' THEN
IF m_axis_tready = '1' THEN -- Downstream not ready: maintain current output valid state
m_axis_tvalid_int <= '0'; -- This implements proper AXI4-Stream backpressure handling
END IF; master_valid_internal <= '1';
ELSIF valid_flag_stage2 = '1' THEN
-- Data output logic: Send processed audio when trigger is active and output is available -- New data available from stage 2: apply LFO_1 effect or bypass
IF trigger = '1' AND (m_axis_tvalid_int = '0' OR m_axis_tready = '1') THEN IF enable_flag_stage2 = '1' THEN
-- Scale down the multiplication result to original audio bit width
-- Right shift by TRIANGULAR_COUNTER_LENGHT effectively divides by 2^TRIANGULAR_COUNTER_LENGHT
-- This maintains proper audio amplitude after modulation
m_axis_tdata <= STD_LOGIC_VECTOR(
resize(
shift_right(
m_axis_tdata_temp, -- Wide multiplication result
TRIANGULAR_COUNTER_LENGHT -- Scale factor
),
CHANNEL_LENGHT -- Final audio sample width
)
);
m_axis_tlast <= s_axis_tlast_reg; -- Output registered channel indicator
m_axis_tvalid_int <= '1'; -- Mark output as valid
trigger <= '0'; -- Clear trigger - data has been output
END IF;
-- Data input logic: Process new audio samples when available and output is ready
IF s_axis_tvalid = '1' AND (m_axis_tready = '1' OR m_axis_tvalid_int = '0') THEN
IF lfo_enable = '1' THEN
-- Apply LFO_1 tremolo effect: multiply audio sample by triangular wave -- Apply LFO_1 tremolo effect: multiply audio sample by triangular wave
-- This creates amplitude modulation (tremolo effect) -- This creates amplitude modulation (tremolo effect)
m_axis_tdata_temp <= signed(s_axis_tdata) * tri_counter; multiplication_result <= STD_LOGIC_VECTOR(
s_axis_tlast_reg <= s_axis_tlast; -- Register channel indicator
ELSE
-- LFO_1 disabled: pass audio through unchanged but maintain bit width
-- Left shift compensates for the right shift that occurs during output
-- This ensures unity gain when LFO_1 is bypassed
m_axis_tdata_temp <= shift_left(
resize( resize(
signed(s_axis_tdata), -- Convert input to signed signed(audio_data_stage2) * signed('0' & triangular_wave_value),
m_axis_tdata_temp'length -- Extend to full processing width multiplication_result'length
), )
TRIANGULAR_COUNTER_LENGHT -- Compensate for output scaling
); );
s_axis_tlast_reg <= s_axis_tlast; -- Register channel indicator -- Scale down result by removing lower bits (equivalent to division by 2^TRIANGULAR_COUNTER_LENGHT)
-- This maintains proper audio amplitude range after multiplication
m_axis_tdata <= multiplication_result(multiplication_result'high DOWNTO TRIANGULAR_COUNTER_LENGHT);
ELSE
-- LFO_1 disabled: pass audio through unchanged (bypass mode)
-- This allows seamless switching between effect and clean audio
m_axis_tdata <= audio_data_stage2;
END IF;
master_valid_internal <= '1'; -- Mark output as valid
ELSE
-- No new data available: clear output valid flag
master_valid_internal <= '0';
END IF; END IF;
trigger <= '1'; -- Set trigger to indicate new processed data is ready -- AXI4-Stream ready signal management for proper flow control
IF master_valid_internal = '1' AND m_axis_tready = '1' THEN
-- Successful output handshake: ready for new input data
slave_ready_internal <= '1';
ELSIF s_axis_tvalid = '1' AND slave_ready_internal = '1' THEN
-- Accepted new input: not ready until current output is consumed
-- This prevents data loss in the pipeline
slave_ready_internal <= '0';
END IF; END IF;
END IF; END IF;
END IF; END IF;
END PROCESS modulation_and_output;
END PROCESS AXIS; -- Output signal assignments
s_axis_tready <= slave_ready_internal; -- Connect internal ready to output port
m_axis_tvalid <= master_valid_internal; -- Connect internal valid to output port
-- LFO_1 Implementation Summary: -- LFO_1 Effect Summary:
-- 1. Generates triangular wave at frequency controlled by joystick input -- 1. Stage 1: Calculates LFO_1 frequency based on joystick position
-- 2. When enabled: multiplies audio samples by triangular wave (tremolo effect) -- 2. Stage 2: Generates triangular wave at calculated frequency
-- 3. When disabled: passes audio through unchanged (bypass mode) -- 3. Stage 3: Multiplies audio samples by triangular wave (tremolo effect)
-- 4. Uses proper AXI4-Stream handshaking for real-time audio processing
-- --
-- Tremolo Effect Characteristics: -- Audio Effect Characteristics:
-- - Tremolo: Periodic amplitude modulation creates "shaking" sound
-- - Frequency range: Approximately 0.1Hz to 10Hz (typical for audio LFO_1) -- - Frequency range: Approximately 0.1Hz to 10Hz (typical for audio LFO_1)
-- - Modulation depth: Controlled by TRIANGULAR_COUNTER_LENGHT generic -- - Modulation depth: Controlled by TRIANGULAR_COUNTER_LENGHT generic
-- - Waveform: Triangular (linear amplitude changes, smooth transitions)
-- - Bypass capability: Clean audio passthrough when disabled -- - Bypass capability: Clean audio passthrough when disabled
--
-- Pipeline Benefits:
-- - Maintains real-time audio processing with no dropouts
-- - Allows complex calculations without affecting audio timing
-- - Provides proper AXI4-Stream flow control and backpressure handling
END ARCHITECTURE Behavioral; END ARCHITECTURE Behavioral;

10
LAB3/src/all_pass_filter.vhd
View File

@@ -4,7 +4,7 @@ USE ieee.numeric_std.ALL;
-- Entity: all_pass_filter -- Entity: all_pass_filter
-- Purpose: A pass-through filter that maintains the same interface and timing -- Purpose: A pass-through filter that maintains the same interface and timing
-- characteristics as a moving average filter but passes data unchanged. -- characteristics as the moving average filter but passes data unchanged.
ENTITY all_pass_filter IS ENTITY all_pass_filter IS
GENERIC ( GENERIC (
TDATA_WIDTH : POSITIVE := 24 -- Width of the data bus in bits TDATA_WIDTH : POSITIVE := 24 -- Width of the data bus in bits
@@ -36,9 +36,9 @@ ARCHITECTURE Behavioral OF all_pass_filter IS
-- Internal slave interface signals -- Internal slave interface signals
SIGNAL s_axis_tready_int : STD_LOGIC := '0'; -- Internal ready signal for input SIGNAL s_axis_tready_int : STD_LOGIC := '0'; -- Internal ready signal for input
SIGNAL s_axis_tlast_reg : STD_LOGIC := '0'; -- Registered version of input tlast SIGNAL s_axis_tlast_reg : STD_LOGIC := '0'; -- Registered version of input tlast
SIGNAL s_axis_tdata_reg : STD_LOGIC_VECTOR(TDATA_WIDTH - 1 DOWNTO 0) := (OTHERS => '0'); -- Temporary storage for input data
-- Internal data storage and master interface signals -- Internal data storage and master interface signals
SIGNAL m_axis_tdata_temp : STD_LOGIC_VECTOR(TDATA_WIDTH - 1 DOWNTO 0) := (OTHERS => '0'); -- Temporary storage for input data
SIGNAL m_axis_tvalid_int : STD_LOGIC := '0'; -- Internal valid signal for output SIGNAL m_axis_tvalid_int : STD_LOGIC := '0'; -- Internal valid signal for output
BEGIN BEGIN
@@ -69,7 +69,7 @@ BEGIN
trigger <= '0'; -- Clear data processing trigger trigger <= '0'; -- Clear data processing trigger
s_axis_tlast_reg <= '0'; -- Clear registered tlast s_axis_tlast_reg <= '0'; -- Clear registered tlast
s_axis_tready_int <= '0'; -- Not ready to accept data during reset s_axis_tready_int <= '0'; -- Not ready to accept data during reset
m_axis_tdata_temp <= (OTHERS => '0'); -- Clear temporary data storage s_axis_tdata_reg <= (OTHERS => '0'); -- Clear temporary data storage
m_axis_tvalid_int <= '0'; -- No valid data on output during reset m_axis_tvalid_int <= '0'; -- No valid data on output during reset
m_axis_tlast <= '0'; -- Clear output tlast m_axis_tlast <= '0'; -- Clear output tlast
@@ -88,7 +88,7 @@ BEGIN
-- (either no valid data pending OR downstream is ready) -- (either no valid data pending OR downstream is ready)
IF trigger = '1' AND (m_axis_tvalid_int = '0' OR m_axis_tready = '1') THEN IF trigger = '1' AND (m_axis_tvalid_int = '0' OR m_axis_tready = '1') THEN
-- Transfer stored data to output -- Transfer stored data to output
m_axis_tdata <= m_axis_tdata_temp; -- Output the stored input data unchanged m_axis_tdata <= s_axis_tdata_reg; -- Output the stored input data unchanged
m_axis_tlast <= s_axis_tlast_reg; -- Output the registered tlast signal m_axis_tlast <= s_axis_tlast_reg; -- Output the registered tlast signal
-- Set output control signals -- Set output control signals
@@ -101,7 +101,7 @@ BEGIN
IF s_axis_tvalid = '1' AND s_axis_tready_int = '1' THEN IF s_axis_tvalid = '1' AND s_axis_tready_int = '1' THEN
-- Store input signals for later output -- Store input signals for later output
s_axis_tlast_reg <= s_axis_tlast; -- Register the tlast signal s_axis_tlast_reg <= s_axis_tlast; -- Register the tlast signal
m_axis_tdata_temp <= s_axis_tdata; -- Store input data (pass-through, no processing) s_axis_tdata_reg <= s_axis_tdata; -- Store input data (pass-through, no processing)
-- Set trigger to indicate data is ready for output -- Set trigger to indicate data is ready for output
trigger <= '1'; trigger <= '1';

7
LAB3/src/digilent_jstk2.vhd
View File

@@ -44,7 +44,7 @@ ARCHITECTURE Behavioral OF digilent_jstk2 IS
-- Calculate delay in clock cycles: (delay_period + 1_SPI_clock_period) * clock_frequency -- Calculate delay in clock cycles: (delay_period + 1_SPI_clock_period) * clock_frequency
-- This ensures proper timing between SPI packets as required by JSTK2 datasheet -- This ensures proper timing between SPI packets as required by JSTK2 datasheet
CONSTANT DELAY_CLK_CYCLES : INTEGER := (DELAY_US + 1_000_000 / SPI_SCLKFREQ) * (CLKFREQ / 1_000_000); CONSTANT DELAY_CLK_CYCLES : INTEGER := (DELAY_US + 1_000_000 / SPI_SCLKFREQ) * (CLKFREQ / 1_000_000) - 1;
-- State machine type definitions -- State machine type definitions
TYPE tx_state_type IS (DELAY, SEND_CMD, SEND_RED, SEND_GREEN, SEND_BLUE, SEND_DUMMY); TYPE tx_state_type IS (DELAY, SEND_CMD, SEND_RED, SEND_GREEN, SEND_BLUE, SEND_DUMMY);
@@ -56,7 +56,7 @@ ARCHITECTURE Behavioral OF digilent_jstk2 IS
-- Timing and data storage signals -- Timing and data storage signals
SIGNAL tx_delay_counter : INTEGER RANGE 0 TO DELAY_CLK_CYCLES := 0; -- Counter for inter-packet delay timing SIGNAL tx_delay_counter : INTEGER RANGE 0 TO DELAY_CLK_CYCLES := 0; -- Counter for inter-packet delay timing
SIGNAL rx_cache : STD_LOGIC_VECTOR(7 DOWNTO 0); -- Temporary storage for multi-byte data reception SIGNAL rx_cache : STD_LOGIC_VECTOR(s_axis_tdata'range); -- Temporary storage for multi-byte data reception
BEGIN BEGIN
@@ -80,7 +80,8 @@ BEGIN
"01101001" WHEN SEND_DUMMY; -- Dummy byte to complete 5-byte transaction "01101001" WHEN SEND_DUMMY; -- Dummy byte to complete 5-byte transaction
-- TX State Machine: Sends LED color commands to JSTK2 module -- TX State Machine: Sends LED color commands to JSTK2 module
-- Protocol: Command(1) + Red(1) + Green(1) + Blue(1) + Dummy(1) = 5 bytes total -- Protocol: Command(1) + Red(1) + Green(1) + Blue(1) + Dummy(1) = 5 bytes total > Delay before next command
-- The delay is required by the JSTK datasheet to ensure proper timing between SPI transactions
TX : PROCESS (aclk) TX : PROCESS (aclk)
BEGIN BEGIN
IF rising_edge(aclk) THEN IF rising_edge(aclk) THEN

41
LAB3/src/effect_selector.vhd
View File

@@ -1,5 +1,6 @@
LIBRARY IEEE; LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL; USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.NUMERIC_STD.ALL;
-- Entity: effect_selector -- Entity: effect_selector
-- Purpose: Routes joystick input to different audio control parameters based on effect mode -- Purpose: Routes joystick input to different audio control parameters based on effect mode
@@ -14,7 +15,7 @@ ENTITY effect_selector IS
aresetn : IN STD_LOGIC; -- Active-low asynchronous reset aresetn : IN STD_LOGIC; -- Active-low asynchronous reset
-- Control and input signals -- Control and input signals
effect : IN STD_LOGIC; -- Effect mode selector (0=volume/balance mode, 1=LFO/balance mode) effect : IN STD_LOGIC; -- Effect mode selector (0=volume/balance mode, 1=LFO)
jstck_x : IN STD_LOGIC_VECTOR(JOYSTICK_LENGHT - 1 DOWNTO 0); -- X-axis joystick position jstck_x : IN STD_LOGIC_VECTOR(JOYSTICK_LENGHT - 1 DOWNTO 0); -- X-axis joystick position
jstck_y : IN STD_LOGIC_VECTOR(JOYSTICK_LENGHT - 1 DOWNTO 0); -- Y-axis joystick position jstck_y : IN STD_LOGIC_VECTOR(JOYSTICK_LENGHT - 1 DOWNTO 0); -- Y-axis joystick position
@@ -27,6 +28,8 @@ END effect_selector;
ARCHITECTURE Behavioral OF effect_selector IS ARCHITECTURE Behavioral OF effect_selector IS
constant JOYSTICK_DEFAULT : STD_LOGIC_VECTOR(JOYSTICK_LENGHT - 1 DOWNTO 0) := STD_LOGIC_VECTOR(to_unsigned(2 ** (JOYSTICK_LENGHT - 1), JOYSTICK_LENGHT)); -- Default joystick value (center position for 10-bit joystick is 512)
BEGIN BEGIN
-- Main control logic process -- Main control logic process
@@ -37,31 +40,35 @@ BEGIN
IF rising_edge(aclk) THEN IF rising_edge(aclk) THEN
IF aresetn = '0' THEN IF aresetn = '0' THEN
-- Reset all outputs to zero (minimum values) -- Reset all outputs to default/center values
volume <= (OTHERS => '0'); -- Minimum volume volume <= JOYSTICK_DEFAULT; -- Default volume (center position)
balance <= (OTHERS => '0'); -- Full left balance balance <= JOYSTICK_DEFAULT; -- Center balance position
lfo_period <= (OTHERS => '0'); -- Minimum LFO period lfo_period <= JOYSTICK_DEFAULT; -- Default LFO period (center position)
ELSE ELSE
-- Normal operation: Route joystick inputs based on effect mode -- Normal operation: Route joystick inputs based on effect mode
-- X-axis always controls balance regardless of mode -- Y-axis always controls different parameters based on effect mode
-- This provides consistent left/right audio balance control -- X-axis behavior differs between modes
balance <= jstck_x; -- Note: When switching between modes, some outputs are reset while others preserved
-- Y-axis control depends on selected effect mode
-- Note: When switching between modes, the previous joystick values
-- are preserved in the non-active outputs (volume/lfo_period)
IF effect = '1' THEN IF effect = '1' THEN
-- LFO Mode: Y-axis controls Low Frequency Oscillator period -- LFO Mode:
-- Used for tremolo, vibrato, or other modulation effects -- Y-axis controls Low Frequency Oscillator period
-- X-axis is ignored in this mode
lfo_period <= jstck_y; lfo_period <= jstck_y;
-- Volume remains at last set value (preserved from previous volume mode)
-- Volume remains at last set value (preserved from previous mode)
-- Reset balance to center/default position when in LFO mode
balance <= JOYSTICK_DEFAULT; -- Reset balance to center position
ELSE ELSE
-- Volume/Balance Mode: Y-axis controls overall volume level -- Volume/Balance Mode:
-- Traditional audio mixer control mode -- Y-axis controls overall volume level
-- X-axis controls left/right audio balance
volume <= jstck_y; volume <= jstck_y;
balance <= jstck_x;
-- LFO period remains at last set value (preserved from previous LFO mode) -- LFO period remains at last set value (preserved from previous LFO mode)
END IF; END IF;

171
LAB3/src/led_level_controller.vhd
View File

@@ -1,11 +1,11 @@
LIBRARY IEEE; LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL; USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.NUMERIC_STD.ALL; USE IEEE.NUMERIC_STD.ALL;
USE IEEE.MATH_REAL.ALL;
-- Entity: led_level_controller -- Entity: led_level_controller
-- Purpose: Audio level meter using LEDs to display real-time audio amplitude -- Purpose: Audio level meter using LEDs to display real-time audio amplitude
-- Processes stereo audio samples and drives a bar graph LED display -- Processes stereo audio samples and drives a bar graph LED display
-- Provides visual feedback of audio signal strength for both channels combined
ENTITY led_level_controller IS ENTITY led_level_controller IS
GENERIC ( GENERIC (
NUM_LEDS : POSITIVE := 16; -- Number of LEDs in the level meter display NUM_LEDS : POSITIVE := 16; -- Number of LEDs in the level meter display
@@ -31,66 +31,53 @@ END led_level_controller;
ARCHITECTURE Behavioral OF led_level_controller IS ARCHITECTURE Behavioral OF led_level_controller IS
-- Calculate number of clock cycles for LED refresh timing -- Calculate clock cycles needed for LED refresh timing
-- Example: 1ms refresh at 100MHz = (1*1,000,000)/10 = 100,000 cycles CONSTANT REFRESH_CYCLES : INTEGER := (refresh_time_ms * 1_000_000) / clock_period_ns - 1;
CONSTANT REFRESH_CYCLES : NATURAL := (refresh_time_ms * 1_000_000) / clock_period_ns;
-- Audio processing signals -- Calculate the number of bits needed to represent the number of LEDs
SIGNAL volume_value : signed(CHANNEL_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Current audio sample (signed) CONSTANT NUMLEDS_BITS : INTEGER := INTEGER(ceil(log2(real(NUM_LEDS))));
SIGNAL abs_audio_left : unsigned(CHANNEL_LENGHT - 2 DOWNTO 0) := (OTHERS => '0'); -- Absolute value of left channel
SIGNAL abs_audio_right : unsigned(CHANNEL_LENGHT - 2 DOWNTO 0) := (OTHERS => '0'); -- Absolute value of right channel
-- LED control signals -- LED refresh timing control signals
SIGNAL leds_int : STD_LOGIC_VECTOR(NUM_LEDS - 1 DOWNTO 0) := (OTHERS => '0'); -- Internal LED state SIGNAL refresh_counter : INTEGER RANGE 0 TO REFRESH_CYCLES := 0; -- Counts clock cycles between LED updates
SIGNAL led_update : STD_LOGIC := '0'; -- Trigger for LED refresh SIGNAL refresh_tick : STD_LOGIC := '0'; -- Pulse signal generated every refresh period
-- Timing control -- Audio amplitude storage for both stereo channels
SIGNAL refresh_counter : NATURAL RANGE 0 TO REFRESH_CYCLES - 1 := 0; -- Counter for refresh timing -- Stores absolute values (magnitude) of left and right audio channels
SIGNAL abs_l : UNSIGNED(CHANNEL_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Absolute left channel amplitude registers
SIGNAL combined_amp : UNSIGNED(CHANNEL_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Combined amplitude for LED level calculation
BEGIN BEGIN
-- Connect internal signals to output ports -- Always ready for AXI4-Stream input
led <= leds_int; -- Drive external LEDs with internal state s_axis_tready <= '1';
s_axis_tready <= '1'; -- Always ready to accept audio data (no backpressure)
-- Audio sample processing and absolute value calculation -- Capture absolute value of input sample for left/right channel
-- Converts signed audio samples to unsigned absolute values for level detection
PROCESS (aclk) PROCESS (aclk)
VARIABLE sdata_signed : signed(CHANNEL_LENGHT - 1 DOWNTO 0); -- Temporary signed audio value
VARIABLE abs_value : unsigned(CHANNEL_LENGHT - 1 DOWNTO 0); -- Temporary absolute value
BEGIN BEGIN
IF rising_edge(aclk) THEN IF rising_edge(aclk) THEN
IF aresetn = '0' THEN IF aresetn = '0' THEN
-- Reset: Clear all audio processing signals -- Reset: Clear both channel amplitude registers
volume_value <= (OTHERS => '0'); -- Clear current sample abs_l <= (OTHERS => '0');
abs_audio_left <= (OTHERS => '0'); -- Clear left channel level combined_amp <= (OTHERS => '0');
abs_audio_right <= (OTHERS => '0'); -- Clear right channel level
ELSIF s_axis_tvalid = '1' THEN ELSIF s_axis_tvalid = '1' THEN
-- Process new audio sample when valid data is available -- Valid audio data received: Process the sample
sdata_signed := signed(s_axis_tdata); -- Convert input to signed format
volume_value <= sdata_signed; -- Store current sample
-- Absolute value calculation for amplitude detection -- Channel routing based on AXI4-Stream tlast signal
-- Handle two's complement signed numbers correctly -- tlast = '1' indicates right channel, tlast = '0' indicates left channel
IF sdata_signed(CHANNEL_LENGHT - 1) = '1' THEN
-- Negative number: Take two's complement to get absolute value
abs_value := unsigned(-sdata_signed);
ELSE
-- Positive number: Direct conversion to unsigned
abs_value := unsigned(sdata_signed);
END IF;
-- Channel assignment based on tlast signal
-- Note: Channel assignment appears reversed from typical convention
IF s_axis_tlast = '1' THEN IF s_axis_tlast = '1' THEN
-- tlast = '1': Assign to left channel -- Right channel: Combine left and right channel amplitudes
abs_audio_left <= abs_value(CHANNEL_LENGHT - 2 DOWNTO 0); -- RESIZE ensures the sum fits within the variable's bit width.
-- There isn't data loss since both abs_l and abs(s_axis_tdata) are one bit shorter than combined_amp,
-- due to the absolute value operation.
combined_amp <= RESIZE(abs_l + UNSIGNED(ABS(SIGNED(s_axis_tdata))), combined_amp'LENGTH);
ELSE ELSE
-- tlast = '0': Assign to right channel -- Left channel: Store absolute value of audio sample
abs_audio_right <= abs_value(CHANNEL_LENGHT - 2 DOWNTO 0); abs_l <= UNSIGNED(ABS(SIGNED(s_axis_tdata)));
END IF; END IF;
END IF; END IF;
@@ -99,27 +86,27 @@ BEGIN
END PROCESS; END PROCESS;
-- LED refresh timing control -- LED refresh tick generator
-- Generates periodic update signals for smooth LED display updates
PROCESS (aclk) PROCESS (aclk)
BEGIN BEGIN
IF rising_edge(aclk) THEN IF rising_edge(aclk) THEN
IF aresetn = '0' THEN IF aresetn = '0' THEN
-- Reset timing control -- Reset: Initialize counter and tick signal
refresh_counter <= 0; -- Clear refresh counter refresh_counter <= 0;
led_update <= '0'; -- Clear update trigger refresh_tick <= '0';
ELSIF refresh_counter = REFRESH_CYCLES - 1 THEN
-- End of refresh period: Trigger LED update
refresh_counter <= 0; -- Reset counter for next period
led_update <= '1'; -- Set update trigger
ELSE ELSE
-- Continue counting refresh period IF refresh_counter = REFRESH_CYCLES THEN
refresh_counter <= refresh_counter + 1; -- Increment counter refresh_counter <= 0;
led_update <= '0'; -- Clear update trigger refresh_tick <= '1';
ELSE
refresh_counter <= refresh_counter + 1;
refresh_tick <= '0';
END IF;
END IF; END IF;
@@ -127,56 +114,46 @@ BEGIN
END PROCESS; END PROCESS;
-- LED level calculation and bar graph generation -- LED level calculation and bar graph generation process
-- Combines left and right channel levels and maps to LED array -- Combines left and right channel amplitudes and converts to LED display pattern
-- Updates only when refresh_tick is active to maintain stable visual display
PROCESS (aclk) PROCESS (aclk)
VARIABLE leds_on : NATURAL RANGE 0 TO NUM_LEDS; -- Number of LEDs to illuminate
VARIABLE temp_led_level : INTEGER RANGE 0 TO NUM_LEDS; -- Calculated LED level VARIABLE led_level : INTEGER RANGE 0 TO 2 ** NUMLEDS_BITS := 0;
VARIABLE abs_audio_sum : unsigned(CHANNEL_LENGHT - 1 DOWNTO 0); -- Combined channel amplitude
BEGIN BEGIN
IF rising_edge(aclk) THEN IF rising_edge(aclk) THEN
IF aresetn = '0' THEN IF aresetn = '0' THEN
-- Reset: Turn off all LEDs -- Reset: Turn off all LEDs and reset level counter
leds_int <= (OTHERS => '0'); led <= (OTHERS => '0');
ELSIF led_update = '1' THEN ELSIF refresh_tick = '1' THEN
-- Update LED display when refresh trigger is active -- LED update cycle: Calculate new LED pattern based on audio amplitude
-- Combine left and right channel amplitudes -- Linear scale to LED level conversion to get the best visual effect
-- Resize both channels to full width before addition to prevent overflow IF combined_amp = 0 THEN
abs_audio_sum := resize(abs_audio_left, CHANNEL_LENGHT) + resize(abs_audio_right, CHANNEL_LENGHT); led_level := 0; -- No audio signal, turn off all LEDs
-- Level calculation with automatic sensitivity scaling
IF (abs_audio_left = 0 AND abs_audio_right = 0) THEN
-- Silence: No LEDs illuminated
temp_led_level := 0;
ELSE ELSE
-- Audio present: Calculate LED level using logarithmic-like scaling led_level := 1 + to_integer(shift_right(combined_amp, CHANNEL_LENGHT - NUMLEDS_BITS));
-- Right shift by (CHANNEL_LENGHT - 4) provides automatic sensitivity adjustment
-- The "1 +" ensures at least one LED is on when audio is present
-- Shift amount determines sensitivity: larger shift = less sensitive
temp_led_level := 1 + to_integer(shift_right(abs_audio_sum, CHANNEL_LENGHT - 4));
END IF; END IF;
-- Limit LED level to available LEDs (prevent array overflow) -- Saturation protection: Limit LED level to maximum available LEDs
IF temp_led_level > NUM_LEDS THEN -- Prevents overflow and ensures the LED index stays within bounds.
leds_on := NUM_LEDS; -- Cap at maximum LEDs IF led_level > NUM_LEDS THEN
ELSE led_level := NUM_LEDS;
leds_on := temp_led_level; -- Use calculated level
END IF; END IF;
-- Generate bar graph pattern: illuminate LEDs from 0 to (leds_on-1) -- Update LED output based on calculated level
-- This creates a classic audio level meter appearance led <= (OTHERS => '0');
leds_int <= (OTHERS => '0'); -- Start with all LEDs off
IF led_level > 0 THEN
led(led_level - 1 DOWNTO 0) <= (OTHERS => '1');
IF leds_on > 0 THEN
-- Turn on LEDs from index 0 up to (leds_on-1)
-- Creates solid bar from bottom to current level
leds_int(leds_on - 1 DOWNTO 0) <= (OTHERS => '1');
END IF; END IF;
END IF; END IF;
@@ -185,18 +162,4 @@ BEGIN
END PROCESS; END PROCESS;
-- LED Level Meter Operation Summary:
-- 1. Continuously samples stereo audio data
-- 2. Calculates absolute value (amplitude) for each channel
-- 3. Combines left and right channels for total signal strength
-- 4. Updates LED display at regular intervals (refresh_time_ms)
-- 5. Maps audio amplitude to number of illuminated LEDs
-- 6. Creates bar graph visualization with automatic sensitivity scaling
--
-- Leds Behavior:
-- - No audio: All LEDs off
-- - Low audio: Few LEDs illuminated (bottom of bar)
-- - High audio: Many LEDs illuminated (full bar)
-- - Overload: All LEDs illuminated (maximum indication)
END Behavioral; END Behavioral;

2
LAB3/src/moving_average_filter.vhd
View File

@@ -3,7 +3,7 @@ USE IEEE.STD_LOGIC_1164.ALL;
USE ieee.numeric_std.ALL; USE ieee.numeric_std.ALL;
-- Entity: moving_average_filter -- Entity: moving_average_filter
-- Purpose: Implements a finite impulse response (FIR) low-pass filter using moving average -- Purpose: Implements a moving average filter for audio data
-- Maintains separate circular buffers for left and right audio channels -- Maintains separate circular buffers for left and right audio channels
-- Filter order is configurable as 2^(FILTER_ORDER_POWER) samples -- Filter order is configurable as 2^(FILTER_ORDER_POWER) samples
ENTITY moving_average_filter IS ENTITY moving_average_filter IS

9
LAB3/src/volume_multiplier.vhd
View File

@@ -58,7 +58,7 @@ BEGIN
-- Volume to exponent conversion process -- Volume to exponent conversion process
-- Converts joystick y-axis position to bit-shift amount for exponential volume scaling -- Converts joystick y-axis position to bit-shift amount for exponential volume scaling
PROCESS (aclk) VOLUME_CALC : PROCESS (aclk)
BEGIN BEGIN
IF rising_edge(aclk) THEN IF rising_edge(aclk) THEN
@@ -78,6 +78,7 @@ BEGIN
-- volume = 0-479: Negative exponent (attenuation, right shift) -- volume = 0-479: Negative exponent (attenuation, right shift)
-- volume = 480-543: Zero exponent (unity gain, dead zone) -- volume = 480-543: Zero exponent (unity gain, dead zone)
-- volume = 544-1023: Positive exponent (amplification, left shift) -- volume = 544-1023: Positive exponent (amplification, left shift)
volume_exp_mult <= to_integer( volume_exp_mult <= to_integer(
shift_right( shift_right(
signed('0' & volume) - to_signed(VOL_MID - DEAD_ZONE, volume'length + 1), signed('0' & volume) - to_signed(VOL_MID - DEAD_ZONE, volume'length + 1),
@@ -89,11 +90,11 @@ BEGIN
END IF; END IF;
END PROCESS; END PROCESS VOLUME_CALC;
-- AXI4-Stream data processing -- AXI4-Stream data processing
-- Applies exponential volume scaling using bit-shifting multiplication -- Applies exponential volume scaling using bit-shifting multiplication
PROCESS (aclk) AXIS : PROCESS (aclk)
BEGIN BEGIN
IF rising_edge(aclk) THEN IF rising_edge(aclk) THEN
@@ -155,7 +156,7 @@ BEGIN
END IF; END IF;
END PROCESS; END PROCESS AXIS;
-- Example scaling factors (VOLUME_STEP_2 = 6, 64 values per step): -- Example scaling factors (VOLUME_STEP_2 = 6, 64 values per step):
-- volume_exp_mult = -3: Divide by 8 (>>3) -- volume_exp_mult = -3: Divide by 8 (>>3)

9
LAB3/src/volume_saturator.vhd
View File

@@ -82,12 +82,10 @@ BEGIN
IF signed(s_axis_tdata) > signed(HIGHER_BOUND_VEC) THEN IF signed(s_axis_tdata) > signed(HIGHER_BOUND_VEC) THEN
-- Positive overflow: Clip to maximum positive value -- Positive overflow: Clip to maximum positive value
-- This prevents "wraparound" distortion from mathematical overflow
m_axis_tdata <= HIGHER_BOUND_VEC; m_axis_tdata <= HIGHER_BOUND_VEC;
ELSIF signed(s_axis_tdata) < signed(LOWER_BOUND_VEC) THEN ELSIF signed(s_axis_tdata) < signed(LOWER_BOUND_VEC) THEN
-- Negative overflow: Clip to maximum negative value -- Negative overflow: Clip to maximum negative value
-- This prevents "wraparound" distortion from mathematical underflow
m_axis_tdata <= LOWER_BOUND_VEC; m_axis_tdata <= LOWER_BOUND_VEC;
ELSE ELSE
@@ -109,11 +107,4 @@ BEGIN
END PROCESS; END PROCESS;
-- Saturation Purpose and Benefits:
-- 1. Prevents audio distortion from mathematical overflow
-- 2. Maintains audio dynamic range within valid bit representation
-- 3. Reduces wide multiplication results back to standard audio format
-- 4. Provides "soft limiting" behavior for volume control
-- 5. Ensures compatibility with downstream audio processing blocks
END Behavioral; END Behavioral;