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Author SHA1 Message Date
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
4 changed files with 422 additions and 466 deletions
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323
LAB3/src/LFO.vhd
View File

@@ -2,16 +2,16 @@ LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.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
-- Creates classic audio effects like vibrato, tremolo, and amplitude modulation
-- Implements a 3-stage pipeline for efficient real-time audio processing
-- This is a simplified, single-process implementation compared to the pipelined version
-- Provides real-time audio amplitude modulation for musical effects
ENTITY LFO IS
GENERIC (
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)
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 (
-- Clock and Reset
@@ -38,219 +38,188 @@ END ENTITY LFO;
ARCHITECTURE Behavioral OF LFO IS
-- Constants for LFO timing configuration
CONSTANT BASE_PERIOD_MICROSECONDS : INTEGER := 1000; -- Base period: 1ms (1kHz base frequency)
CONSTANT FREQUENCY_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)
-- LFO timing configuration constants
CONSTANT LFO_COUNTER_BASE_PERIOD_US : INTEGER := 1000; -- Base period: 1ms (1kHz base frequency)
CONSTANT 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)
-- 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
-- Minimum frequency (fastest LFO): occurs when joystick is at minimum position
CONSTANT MIN_CLOCK_CYCLES : INTEGER := BASE_CLOCK_CYCLES - FREQUENCY_ADJUSTMENT_FACTOR * (2 ** (JOYSTICK_LENGHT - 1));
-- 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);
CONSTANT LFO_CLK_CYCLES_MIN : INTEGER := LFO_COUNTER_BASE_CLK_CYCLES - ADJUSTMENT_FACTOR * (2 ** (JOYSTICK_LENGHT - 1)); -- 53,920 clk cycles (faster)
CONSTANT LFO_CLK_CYCLES_MAX : INTEGER := LFO_COUNTER_BASE_CLK_CYCLES + ADJUSTMENT_FACTOR * (2 ** (JOYSTICK_LENGHT - 1) - 1); -- 145,990 clk cycles (slower)
-- Internal signals for LFO control
-- Period adjustment based on joystick input (positive = slower, negative = faster)
SIGNAL period_adjustment_delta : INTEGER RANGE - 2 ** (JOYSTICK_LENGHT - 1) * FREQUENCY_ADJUSTMENT_FACTOR
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;
-- LFO timing control signals
SIGNAL step_clk_cycles_delta : INTEGER RANGE - 2 ** (JOYSTICK_LENGHT - 1) * ADJUSTMENT_FACTOR TO (2 ** (JOYSTICK_LENGHT - 1) - 1) * ADJUSTMENT_FACTOR := 0;
SIGNAL step_clk_cycles : INTEGER RANGE LFO_CLK_CYCLES_MIN TO LFO_CLK_CYCLES_MAX := LFO_COUNTER_BASE_CLK_CYCLES;
SIGNAL step_counter : NATURAL RANGE 0 TO LFO_CLK_CYCLES_MAX := 0;
-- Pipeline stage 1 registers - Input processing and period calculation
SIGNAL audio_data_stage1 : STD_LOGIC_VECTOR(CHANNEL_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Registered audio input
SIGNAL enable_flag_stage1 : STD_LOGIC := '0'; -- Registered LFO enable
SIGNAL valid_flag_stage1 : STD_LOGIC := '0'; -- Valid data in stage 1
SIGNAL last_flag_stage1 : STD_LOGIC := '0'; -- Registered channel indicator
-- Triangular wave generation signals
-- Note: Using signed counter with extra bit to handle full range calculations
SIGNAL tri_counter : SIGNED(TRIANGULAR_COUNTER_LENGHT DOWNTO 0) := (OTHERS => '0'); -- Triangular wave amplitude
SIGNAL direction_up : STD_LOGIC := '1'; -- Wave direction: '1' = ascending, '0' = descending
-- Pipeline stage 2 registers - Triangular wave generation
SIGNAL triangular_wave_value : unsigned(TRIANGULAR_COUNTER_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Current triangular wave amplitude
SIGNAL wave_direction_up : STD_LOGIC := '1'; -- Triangle wave direction: '1' = ascending, '0' = descending
SIGNAL timing_counter : NATURAL RANGE 0 TO MAX_CLOCK_CYCLES := 0; -- Clock cycle counter for LFO timing
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
-- AXI4-Stream control signals
SIGNAL trigger : STD_LOGIC := '0'; -- Trigger to indicate new processed data is ready
SIGNAL s_axis_tlast_reg : STD_LOGIC := '0'; -- Registered version of tlast for output synchronization
SIGNAL m_axis_tvalid_int : STD_LOGIC := '0'; -- Internal output valid signal
-- Pipeline stage 3 registers - Modulation and output
-- Extended width to accommodate multiplication result before scaling
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
-- Audio processing signal with extended width for multiplication
-- Width accommodates: audio sample + triangular counter to prevent overflow
SIGNAL m_axis_tdata_temp : SIGNED(CHANNEL_LENGHT + TRIANGULAR_COUNTER_LENGHT DOWNTO 0) := (OTHERS => '0');
BEGIN
-- Direct connection: tlast passes through unchanged (maintains channel timing)
m_axis_tlast <= last_flag_stage1;
-- Output signal assignments with proper AXI4-Stream flow control
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
-- This stage captures input data and calculates the LFO period based on joystick position
input_processing_stage : PROCESS (aclk)
-- Optimized single process for LFO timing and triangular waveform generation
-- This process handles both the frequency control and wave shape generation
triangular_wave_lfo_generator : PROCESS (aclk)
BEGIN
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
-- Reset all stage 1 registers to safe initial states
audio_data_stage1 <= (OTHERS => '0'); -- Clear audio data
current_period_cycles <= BASE_CLOCK_CYCLES; -- Set to base frequency
enable_flag_stage1 <= '0'; -- Disable LFO
valid_flag_stage1 <= '0'; -- No valid data
last_flag_stage1 <= '0'; -- Clear channel indicator
-- Reset LFO generator to initial state
step_clk_cycles <= LFO_COUNTER_BASE_CLK_CYCLES; -- Set to base frequency
step_counter <= 0; -- Clear timing counter
tri_counter <= (OTHERS => '0'); -- Start triangular wave at zero
direction_up <= '1'; -- Start counting up
ELSE
-- Calculate LFO period based on joystick y-axis input
-- Calculate LFO period based on joystick input
-- Joystick mapping:
-- 0-511: Faster than base frequency (shorter period)
-- 0-511: Faster than base frequency (shorter period, higher frequency)
-- 512: Base frequency (1kHz)
-- 513-1023: Slower than base frequency (longer period)
period_adjustment_delta <= (to_integer(unsigned(lfo_period)) - JOYSTICK_CENTER_VALUE) * FREQUENCY_ADJUSTMENT_FACTOR;
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
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
-- 513-1023: Slower than base frequency (longer period, lower frequency)
step_clk_cycles_delta <= (to_integer(unsigned(lfo_period)) - JSTK_CENTER_VALUE) * ADJUSTMENT_FACTOR;
step_clk_cycles <= LFO_COUNTER_BASE_CLK_CYCLES - step_clk_cycles_delta;
-- Generate triangular wave when LFO is enabled
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
IF lfo_enable = '1' THEN
-- 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 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
-- Update triangular wave: count up or down based on current direction
-- This creates the classic triangular waveform shape
IF wave_direction_up = '1' THEN
-- 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
triangular_wave_value <= triangular_wave_value + 1; -- Continue increasing
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
-- This stage applies the LFO effect by multiplying audio samples with the triangular wave
modulation_and_output : PROCESS (aclk)
-- Update triangular wave value based on current direction
-- This creates the classic triangular waveform shape
IF direction_up = '1' THEN
tri_counter <= tri_counter + 1; -- Ascending: increment
ELSE
tri_counter <= tri_counter - 1; -- Descending: decrement
END IF;
ELSE
step_counter <= step_counter + 1; -- Continue counting towards next update
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
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
-- Reset output stage to safe initial state
m_axis_tdata <= (OTHERS => '0'); -- Clear output data
master_valid_internal <= '0'; -- No valid output
slave_ready_internal <= '1'; -- Ready to accept input
-- Reset AXI4-Stream interface and audio processing
s_axis_tlast_reg <= '0'; -- Clear registered channel indicator
m_axis_tdata_temp <= (OTHERS => '0'); -- Clear temporary audio data
m_axis_tvalid_int <= '0'; -- No valid output data
m_axis_tlast <= '0'; -- Clear output channel indicator
ELSE
-- Output flow control: handle backpressure from downstream modules
IF master_valid_internal = '1' AND m_axis_tready = '0' THEN
-- Downstream not ready: maintain current output valid state
-- This implements proper AXI4-Stream backpressure handling
master_valid_internal <= '1';
ELSIF valid_flag_stage2 = '1' THEN
-- New data available from stage 2: apply LFO effect or bypass
IF enable_flag_stage2 = '1' THEN
-- Output handshake management:
-- Clear valid flag when downstream accepts data
IF m_axis_tready = '1' THEN
m_axis_tvalid_int <= '0';
END IF;
-- Data output logic: Send processed audio when trigger is active and output is available
IF trigger = '1' AND (m_axis_tvalid_int = '0' OR m_axis_tready = '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 tremolo effect: multiply audio sample by triangular wave
-- This creates amplitude modulation (tremolo effect)
multiplication_result <= STD_LOGIC_VECTOR(
resize(
signed(audio_data_stage2) * signed('0' & triangular_wave_value),
multiplication_result'length
)
);
-- 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);
m_axis_tdata_temp <= signed(s_axis_tdata) * tri_counter;
s_axis_tlast_reg <= s_axis_tlast; -- Register channel indicator
ELSE
-- LFO disabled: pass audio through unchanged (bypass mode)
-- This allows seamless switching between effect and clean audio
m_axis_tdata <= audio_data_stage2;
-- LFO 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 is bypassed
m_axis_tdata_temp <= shift_left(
resize(
signed(s_axis_tdata), -- Convert input to signed
m_axis_tdata_temp'length -- Extend to full processing width
),
TRIANGULAR_COUNTER_LENGHT -- Compensate for output scaling
);
s_axis_tlast_reg <= s_axis_tlast; -- Register channel indicator
END IF;
master_valid_internal <= '1'; -- Mark output as valid
ELSE
-- No new data available: clear output valid flag
master_valid_internal <= '0';
trigger <= '1'; -- Set trigger to indicate new processed data is ready
END IF;
-- 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 PROCESS modulation_and_output;
-- 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
END PROCESS AXIS;
-- LFO Effect Summary:
-- 1. Stage 1: Calculates LFO frequency based on joystick position
-- 2. Stage 2: Generates triangular wave at calculated frequency
-- 3. Stage 3: Multiplies audio samples by triangular wave (tremolo effect)
-- LFO Implementation Summary:
-- 1. Generates triangular wave at frequency controlled by joystick input
-- 2. When enabled: multiplies audio samples by triangular wave (tremolo effect)
-- 3. When disabled: passes audio through unchanged (bypass mode)
-- 4. Uses proper AXI4-Stream handshaking for real-time audio processing
--
-- Audio Effect Characteristics:
-- - Tremolo: Periodic amplitude modulation creates "shaking" sound
-- Tremolo Effect Characteristics:
-- - Frequency range: Approximately 0.1Hz to 10Hz (typical for audio LFO)
-- - Modulation depth: Controlled by TRIANGULAR_COUNTER_LENGHT generic
-- - Waveform: Triangular (linear amplitude changes, smooth transitions)
-- - 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;

313
LAB3/src/LFO_1.vhd
View File

@@ -2,16 +2,16 @@ LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.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
-- This is a simplified, single-process implementation compared to the pipelined version
-- Provides real-time audio amplitude modulation for musical effects
-- Creates classic audio effects like vibrato, tremolo, and amplitude modulation
-- Implements a 3-stage pipeline for efficient real-time audio processing
ENTITY LFO_1 IS
GENERIC (
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)
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 (
-- Clock and Reset
@@ -38,188 +38,219 @@ END ENTITY LFO_1;
ARCHITECTURE Behavioral OF LFO_1 IS
-- LFO_1 timing configuration constants
CONSTANT LFO_1_COUNTER_BASE_PERIOD_US : INTEGER := 1000; -- Base period: 1ms (1kHz base frequency)
CONSTANT 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)
-- Constants for LFO_1 timing configuration
CONSTANT BASE_PERIOD_MICROSECONDS : INTEGER := 1000; -- Base period: 1ms (1kHz base frequency)
CONSTANT FREQUENCY_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)
-- 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
CONSTANT LFO_1_CLK_CYCLES_MIN : INTEGER := LFO_1_COUNTER_BASE_CLK_CYCLES - ADJUSTMENT_FACTOR * (2 ** (JOYSTICK_LENGHT - 1)); -- 53,920 clk cycles (faster)
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)
-- Minimum frequency (fastest LFO_1): occurs when joystick is at minimum position
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
SIGNAL step_clk_cycles_delta : INTEGER RANGE - 2 ** (JOYSTICK_LENGHT - 1) * ADJUSTMENT_FACTOR TO (2 ** (JOYSTICK_LENGHT - 1) - 1) * ADJUSTMENT_FACTOR := 0;
SIGNAL step_clk_cycles : INTEGER RANGE LFO_1_CLK_CYCLES_MIN TO LFO_1_CLK_CYCLES_MAX := LFO_1_COUNTER_BASE_CLK_CYCLES;
SIGNAL step_counter : NATURAL RANGE 0 TO LFO_1_CLK_CYCLES_MAX := 0;
-- Internal signals for LFO_1 control
-- Period adjustment based on joystick input (positive = slower, negative = faster)
SIGNAL period_adjustment_delta : INTEGER RANGE - 2 ** (JOYSTICK_LENGHT - 1) * FREQUENCY_ADJUSTMENT_FACTOR
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
-- Note: Using signed counter with extra bit to handle full range calculations
SIGNAL tri_counter : SIGNED(TRIANGULAR_COUNTER_LENGHT DOWNTO 0) := (OTHERS => '0'); -- Triangular wave amplitude
SIGNAL direction_up : STD_LOGIC := '1'; -- Wave direction: '1' = ascending, '0' = descending
-- Pipeline stage 1 registers - Input processing and period calculation
SIGNAL audio_data_stage1 : STD_LOGIC_VECTOR(CHANNEL_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Registered audio input
SIGNAL enable_flag_stage1 : STD_LOGIC := '0'; -- Registered LFO_1 enable
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
SIGNAL trigger : STD_LOGIC := '0'; -- Trigger to indicate new processed data is ready
SIGNAL s_axis_tlast_reg : STD_LOGIC := '0'; -- Registered version of tlast for output synchronization
SIGNAL m_axis_tvalid_int : STD_LOGIC := '0'; -- Internal output valid signal
-- Pipeline stage 2 registers - Triangular wave generation
SIGNAL triangular_wave_value : unsigned(TRIANGULAR_COUNTER_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Current triangular wave amplitude
SIGNAL wave_direction_up : STD_LOGIC := '1'; -- Triangle wave direction: '1' = ascending, '0' = descending
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
-- Width accommodates: audio sample + triangular counter to prevent overflow
SIGNAL m_axis_tdata_temp : SIGNED(CHANNEL_LENGHT + TRIANGULAR_COUNTER_LENGHT DOWNTO 0) := (OTHERS => '0');
-- Pipeline stage 3 registers - Modulation and output
-- Extended width to accommodate multiplication result before scaling
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
-- Output signal assignments with proper AXI4-Stream flow control
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;
-- Direct connection: tlast passes through unchanged (maintains channel timing)
m_axis_tlast <= last_flag_stage1;
-- Optimized single process for LFO_1 timing and triangular waveform generation
-- This process handles both the frequency control and wave shape generation
triangular_wave_lfo_generator : PROCESS (aclk)
-- Pipeline stage 1: Input registration and LFO_1 period calculation
-- This stage captures input data and calculates the LFO_1 period based on joystick position
input_processing_stage : PROCESS (aclk)
BEGIN
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
-- Reset LFO_1 generator to initial state
step_clk_cycles <= LFO_1_COUNTER_BASE_CLK_CYCLES; -- Set to base frequency
step_counter <= 0; -- Clear timing counter
tri_counter <= (OTHERS => '0'); -- Start triangular wave at zero
direction_up <= '1'; -- Start counting up
-- Reset all stage 1 registers to safe initial states
audio_data_stage1 <= (OTHERS => '0'); -- Clear audio data
current_period_cycles <= BASE_CLOCK_CYCLES; -- Set to base frequency
enable_flag_stage1 <= '0'; -- Disable LFO_1
valid_flag_stage1 <= '0'; -- No valid data
last_flag_stage1 <= '0'; -- Clear channel indicator
ELSE
-- Calculate LFO_1 period based on joystick input
-- Calculate LFO_1 period based on joystick y-axis input
-- Joystick mapping:
-- 0-511: Faster than base frequency (shorter period, higher frequency)
-- 0-511: Faster than base frequency (shorter period)
-- 512: Base frequency (1kHz)
-- 513-1023: Slower than base frequency (longer period, lower frequency)
step_clk_cycles_delta <= (to_integer(unsigned(lfo_period)) - JSTK_CENTER_VALUE) * ADJUSTMENT_FACTOR;
step_clk_cycles <= LFO_1_COUNTER_BASE_CLK_CYCLES - step_clk_cycles_delta;
-- 513-1023: Slower than base frequency (longer period)
period_adjustment_delta <= (to_integer(unsigned(lfo_period)) - JOYSTICK_CENTER_VALUE) * FREQUENCY_ADJUSTMENT_FACTOR;
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
IF lfo_enable = '1' THEN
-- 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 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
IF direction_up = '1' THEN
tri_counter <= tri_counter + 1; -- Ascending: increment
ELSE
tri_counter <= tri_counter - 1; -- Descending: decrement
END IF;
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
step_counter <= step_counter + 1; -- Continue counting towards next update
timing_counter <= 0; -- Reset counter for next period
-- Update triangular wave: count up or down based on current direction
-- This creates the classic triangular waveform shape
IF wave_direction_up = '1' THEN
-- 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
triangular_wave_value <= triangular_wave_value + 1; -- Continue increasing
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_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 PROCESS triangular_wave_generator;
END PROCESS triangular_wave_lfo_generator;
-- AXI4-Stream handshake logic and audio processing
-- This process handles input/output data flow and applies the LFO_1 modulation
AXIS : PROCESS (aclk)
-- Pipeline stage 3: Audio modulation and output control
-- This stage applies the LFO_1 effect by multiplying audio samples with the triangular wave
modulation_and_output : PROCESS (aclk)
BEGIN
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
-- Reset AXI4-Stream interface and audio processing
s_axis_tlast_reg <= '0'; -- Clear registered channel indicator
m_axis_tdata_temp <= (OTHERS => '0'); -- Clear temporary audio data
m_axis_tvalid_int <= '0'; -- No valid output data
m_axis_tlast <= '0'; -- Clear output channel indicator
-- Reset output stage to safe initial state
m_axis_tdata <= (OTHERS => '0'); -- Clear output data
master_valid_internal <= '0'; -- No valid output
slave_ready_internal <= '1'; -- Ready to accept input
ELSE
-- Output handshake management:
-- Clear valid flag when downstream accepts data
IF m_axis_tready = '1' THEN
m_axis_tvalid_int <= '0';
END IF;
-- Data output logic: Send processed audio when trigger is active and output is available
IF trigger = '1' AND (m_axis_tvalid_int = '0' OR m_axis_tready = '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
-- Output flow control: handle backpressure from downstream modules
IF master_valid_internal = '1' AND m_axis_tready = '0' THEN
-- Downstream not ready: maintain current output valid state
-- This implements proper AXI4-Stream backpressure handling
master_valid_internal <= '1';
ELSIF valid_flag_stage2 = '1' THEN
-- New data available from stage 2: apply LFO_1 effect or bypass
IF enable_flag_stage2 = '1' THEN
-- Apply LFO_1 tremolo effect: multiply audio sample by triangular wave
-- This creates amplitude modulation (tremolo effect)
m_axis_tdata_temp <= signed(s_axis_tdata) * tri_counter;
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(
multiplication_result <= STD_LOGIC_VECTOR(
resize(
signed(s_axis_tdata), -- Convert input to signed
m_axis_tdata_temp'length -- Extend to full processing width
),
TRIANGULAR_COUNTER_LENGHT -- Compensate for output scaling
signed(audio_data_stage2) * signed('0' & triangular_wave_value),
multiplication_result'length
)
);
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;
trigger <= '1'; -- Set trigger to indicate new processed data is ready
master_valid_internal <= '1'; -- Mark output as valid
ELSE
-- No new data available: clear output valid flag
master_valid_internal <= '0';
END IF;
-- 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 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:
-- 1. Generates triangular wave at frequency controlled by joystick input
-- 2. When enabled: multiplies audio samples by triangular wave (tremolo effect)
-- 3. When disabled: passes audio through unchanged (bypass mode)
-- 4. Uses proper AXI4-Stream handshaking for real-time audio processing
-- LFO_1 Effect Summary:
-- 1. Stage 1: Calculates LFO_1 frequency based on joystick position
-- 2. Stage 2: Generates triangular wave at calculated frequency
-- 3. Stage 3: Multiplies audio samples by triangular wave (tremolo effect)
--
-- 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)
-- - Modulation depth: Controlled by TRIANGULAR_COUNTER_LENGHT generic
-- - Waveform: Triangular (linear amplitude changes, smooth transitions)
-- - 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;

33
LAB3/src/effect_selector.vhd
View File

@@ -1,5 +1,6 @@
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.NUMERIC_STD.ALL;
-- Entity: effect_selector
-- 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
-- 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_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
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
BEGIN
-- Main control logic process
@@ -37,31 +40,33 @@ BEGIN
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
-- Reset all outputs to zero (minimum values)
volume <= (OTHERS => '0'); -- Minimum volume
balance <= (OTHERS => '0'); -- Full left balance
lfo_period <= (OTHERS => '0'); -- Minimum LFO period
-- Reset all outputs to default/center values
volume <= JOYSTICK_DEFAULT; -- Default volume (center position)
balance <= JOYSTICK_DEFAULT; -- Center balance position
lfo_period <= JOYSTICK_DEFAULT; -- Default LFO period (center position)
ELSE
-- Normal operation: Route joystick inputs based on effect mode
-- X-axis always controls balance regardless of mode
-- This provides consistent left/right audio balance control
balance <= jstck_x;
-- 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)
-- Y-axis always controls different parameters based on effect mode
-- X-axis behavior differs between modes
-- Note: When switching between modes, some outputs are reset while others preserved
IF effect = '1' THEN
-- LFO Mode: Y-axis controls Low Frequency Oscillator period
-- Used for tremolo, vibrato, or other modulation effects
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
-- Volume/Balance Mode: Y-axis controls overall volume level
-- Volume/Balance Mode:
-- Y-axis controls overall volume level
-- X-axis controls left/right audio balance
-- Traditional audio mixer control mode
volume <= jstck_y;
balance <= jstck_x;
-- LFO period remains at last set value (preserved from previous LFO mode)
END IF;

219
LAB3/src/led_level_controller.vhd
View File

@@ -8,195 +8,146 @@ USE IEEE.NUMERIC_STD.ALL;
-- Provides visual feedback of audio signal strength for both channels combined
ENTITY led_level_controller IS
GENERIC (
NUM_LEDS : POSITIVE := 16; -- Number of LEDs in the level meter display
CHANNEL_LENGHT : POSITIVE := 24; -- Width of audio data (24-bit audio samples)
refresh_time_ms : POSITIVE := 1; -- LED refresh rate in milliseconds (1ms = 1kHz update rate)
clock_period_ns : POSITIVE := 10 -- System clock period in nanoseconds (10ns = 100MHz)
NUM_LEDS : POSITIVE := 16; -- Number of LEDs in the level meter display
CHANNEL_LENGHT : POSITIVE := 24; -- Width of audio data (24-bit audio samples)
refresh_time_ms : POSITIVE := 1; -- LED refresh rate in milliseconds (1ms = 1kHz update rate)
clock_period_ns : POSITIVE := 10 -- System clock period in nanoseconds (10ns = 100MHz)
);
PORT (
-- Clock and reset signals
aclk : IN STD_LOGIC; -- Main clock input
aresetn : IN STD_LOGIC; -- Active-low asynchronous reset
aclk : IN STD_LOGIC; -- Main clock input
aresetn : IN STD_LOGIC; -- Active-low asynchronous reset
-- LED output array (bar graph display)
led : OUT STD_LOGIC_VECTOR(NUM_LEDS - 1 DOWNTO 0); -- LED control signals (1=on, 0=off)
led : OUT STD_LOGIC_VECTOR(NUM_LEDS - 1 DOWNTO 0); -- LED control signals (1=on, 0=off)
-- AXI4-Stream Slave Interface (Audio Input)
s_axis_tvalid : IN STD_LOGIC; -- Input data valid signal
s_axis_tdata : IN STD_LOGIC_VECTOR(CHANNEL_LENGHT - 1 DOWNTO 0); -- Audio sample input
s_axis_tlast : IN STD_LOGIC; -- Channel indicator (0=right, 1=left)
s_axis_tready : OUT STD_LOGIC -- Always ready to accept data
s_axis_tvalid : IN STD_LOGIC; -- Input data valid signal
s_axis_tdata : IN STD_LOGIC_VECTOR(CHANNEL_LENGHT - 1 DOWNTO 0); -- Audio sample input
s_axis_tlast : IN STD_LOGIC; -- Channel indicator (0=right, 1=left)
s_axis_tready : OUT STD_LOGIC -- Always ready to accept data
);
END led_level_controller;
ARCHITECTURE Behavioral OF led_level_controller IS
-- Calculate number of clock cycles for LED refresh timing
-- Example: 1ms refresh at 100MHz = (1*1,000,000)/10 = 100,000 cycles
CONSTANT REFRESH_CYCLES : NATURAL := (refresh_time_ms * 1_000_000) / clock_period_ns;
-- Calculate clock cycles needed for LED refresh timing
-- Formula: (refresh_time_ms * 1_000_000 ns/ms) / clock_period_ns
-- Example: (1ms * 1,000,000) / 10ns = 100,000 cycles for 1ms refresh at 100MHz
CONSTANT REFRESH_CYCLES : INTEGER := (refresh_time_ms * 1_000_000) / clock_period_ns;
-- Audio processing signals
SIGNAL volume_value : signed(CHANNEL_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Current audio sample (signed)
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 refresh timing control signals
SIGNAL refresh_counter : INTEGER RANGE 0 TO REFRESH_CYCLES := 0; -- Counts clock cycles between LED updates
SIGNAL refresh_tick : STD_LOGIC := '0'; -- Pulse signal generated every refresh period
-- LED control signals
SIGNAL leds_int : STD_LOGIC_VECTOR(NUM_LEDS - 1 DOWNTO 0) := (OTHERS => '0'); -- Internal LED state
SIGNAL led_update : STD_LOGIC := '0'; -- Trigger for LED refresh
-- Timing control
SIGNAL refresh_counter : NATURAL RANGE 0 TO REFRESH_CYCLES - 1 := 0; -- Counter for refresh timing
-- Audio amplitude storage for both stereo channels
-- Stores absolute values (magnitude) of left and right audio channels
SIGNAL abs_l, abs_r : UNSIGNED(CHANNEL_LENGHT - 1 DOWNTO 0) := (OTHERS => '0'); -- Absolute amplitude registers
BEGIN
-- Connect internal signals to output ports
led <= leds_int; -- Drive external LEDs with internal state
s_axis_tready <= '1'; -- Always ready to accept audio data (no backpressure)
-- AXI4-Stream interface: Always ready to receive audio data
-- This ensures continuous audio processing without backpressure
s_axis_tready <= '1';
-- Audio sample processing and absolute value calculation
-- Converts signed audio samples to unsigned absolute values for level detection
-- Audio sample acquisition process based on channel identification
-- Processes incoming stereo audio samples and converts to absolute amplitude values
-- Uses s_axis_tlast to distinguish between left (1) and right (0) channels
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
VARIABLE signed_sample : SIGNED(CHANNEL_LENGHT - 1 DOWNTO 0); -- Temporary variable for signed arithmetic
BEGIN
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
-- Reset: Clear all audio processing signals
volume_value <= (OTHERS => '0'); -- Clear current sample
abs_audio_left <= (OTHERS => '0'); -- Clear left channel level
abs_audio_right <= (OTHERS => '0'); -- Clear right channel level
-- Reset: Clear both channel amplitude registers
abs_l <= (OTHERS => '0');
abs_r <= (OTHERS => '0');
ELSIF s_axis_tvalid = '1' THEN
-- Process new audio sample when valid data is available
sdata_signed := signed(s_axis_tdata); -- Convert input to signed format
volume_value <= sdata_signed; -- Store current sample
-- Valid audio data received: Process the sample
signed_sample := SIGNED(s_axis_tdata); -- Convert input to signed for ABS operation
-- Absolute value calculation for amplitude detection
-- Handle two's complement signed numbers correctly
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
-- Channel routing based on AXI4-Stream tlast signal
-- tlast = '1' indicates left channel, tlast = '0' indicates right channel
IF s_axis_tlast = '1' THEN
-- tlast = '1': Assign to left channel
abs_audio_left <= abs_value(CHANNEL_LENGHT - 2 DOWNTO 0);
-- Left channel: Store absolute value of audio sample
abs_l <= UNSIGNED(ABS(signed_sample));
ELSE
-- tlast = '0': Assign to right channel
abs_audio_right <= abs_value(CHANNEL_LENGHT - 2 DOWNTO 0);
-- Right channel: Store absolute value of audio sample
abs_r <= UNSIGNED(ABS(signed_sample));
END IF;
END IF;
END IF;
END PROCESS;
-- LED refresh timing control
-- Generates periodic update signals for smooth LED display updates
-- LED refresh timing generator process
-- Creates a periodic tick signal to control LED update rate
-- Prevents LED flickering by limiting update frequency to human-visible rates
PROCESS (aclk)
BEGIN
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
-- Reset timing control
refresh_counter <= 0; -- Clear refresh counter
led_update <= '0'; -- Clear update trigger
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
-- Reset: Initialize counter and tick signal
refresh_counter <= 0;
refresh_tick <= '0';
ELSE
-- Continue counting refresh period
refresh_counter <= refresh_counter + 1; -- Increment counter
led_update <= '0'; -- Clear update trigger
-- Normal operation: Count clock cycles and generate refresh tick
IF refresh_counter = REFRESH_CYCLES - 1 THEN
-- End of refresh period: Reset counter and generate tick pulse
refresh_counter <= 0;
refresh_tick <= '1'; -- Single clock cycle pulse for LED update
ELSE
-- Continue counting: Increment counter, no tick
refresh_counter <= refresh_counter + 1;
refresh_tick <= '0';
END IF;
END IF;
END IF;
END PROCESS;
-- LED level calculation and bar graph generation
-- Combines left and right channel levels and maps to LED array
-- LED level calculation and bar graph generation process
-- 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)
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 abs_audio_sum : unsigned(CHANNEL_LENGHT - 1 DOWNTO 0); -- Combined channel amplitude
VARIABLE combined_amp : UNSIGNED(CHANNEL_LENGHT - 1 DOWNTO 0); -- Combined amplitude of both channels
VARIABLE led_level : INTEGER RANGE 0 TO NUM_LEDS := 0; -- Calculated LED level for bar graph display
BEGIN
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
-- Reset: Turn off all LEDs
leds_int <= (OTHERS => '0');
-- Reset: Turn off all LEDs and reset level counter
led <= (OTHERS => '0');
ELSIF led_update = '1' THEN
-- Update LED display when refresh trigger is active
ELSIF refresh_tick = '1' THEN
-- LED update cycle: Calculate new LED pattern based on audio amplitude
-- This section is executed once per refresh_tick to avoid flicker and ensure a stable display.
-- Combine left and right channel amplitudes
-- Resize both channels to full width before addition to prevent overflow
abs_audio_sum := resize(abs_audio_left, CHANNEL_LENGHT) + resize(abs_audio_right, CHANNEL_LENGHT);
-- The sum of the absolute values of both channels gives a measure of total audio energy.
-- RESIZE ensures the sum fits within the variable's bit width.
combined_amp := RESIZE(abs_l + abs_r, combined_amp'LENGTH);
-- 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
-- Audio present: Calculate LED level using logarithmic-like scaling
-- 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));
-- Normalize combined amplitude to LED scale (0 to NUM_LEDS)
-- The combined amplitude is mapped to the number of LEDs using a right shift.
-- For 24-bit audio, shifting by (CHANNEL_LENGHT - 4) reduces the range to approximately 4 bits (0-15).
-- Adding 1 ensures that at least one LED lights up for any non-zero audio input.
-- Example: For 24-bit input, 1 + (combined_amp >> 20) gives a range from 1 to 16.
led_level := 1 + to_integer(shift_right(combined_amp, CHANNEL_LENGHT - 4));
-- Saturation protection: Limit LED level to maximum available LEDs
-- Prevents overflow and ensures the LED index stays within bounds.
IF led_level > NUM_LEDS THEN
led_level := NUM_LEDS;
END IF;
-- Limit LED level to available LEDs (prevent array overflow)
IF temp_led_level > NUM_LEDS THEN
leds_on := NUM_LEDS; -- Cap at maximum LEDs
ELSE
leds_on := temp_led_level; -- Use calculated level
-- Generate bar graph LED pattern
-- Implements a "thermometer" style display: all LEDs from 0 up to (led_level-1) are ON.
-- All higher LEDs remain OFF.
-- The assignment first turns all LEDs OFF, then sets the lower 'led_level' LEDs ON.
led <= (OTHERS => '0');
IF led_level > 0 THEN
led(led_level - 1 DOWNTO 0) <= (OTHERS => '1');
END IF;
-- Generate bar graph pattern: illuminate LEDs from 0 to (leds_on-1)
-- This creates a classic audio level meter appearance
leds_int <= (OTHERS => '0'); -- Start with all LEDs off
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 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;