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This commit is contained in:
Davide Cavagnola
2025-05-27 17:42:40 +02:00
parent d1cfa6443b
commit 82d76e48d8
15 changed files with 1626 additions and 1047 deletions
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LAB3/src/led_level_controller.vhd
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@@ -2,121 +2,201 @@ LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.NUMERIC_STD.ALL;
-- Entity: led_level_controller
-- Purpose: Audio level meter using LEDs to display real-time audio amplitude
-- 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
GENERIC (
NUM_LEDS : POSITIVE := 16;
CHANNEL_LENGHT : POSITIVE := 24;
refresh_time_ms : POSITIVE := 1;
clock_period_ns : POSITIVE := 10
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;
aresetn : IN STD_LOGIC;
led : OUT STD_LOGIC_VECTOR(NUM_LEDS - 1 DOWNTO 0);
s_axis_tvalid : IN STD_LOGIC;
s_axis_tdata : IN STD_LOGIC_VECTOR(CHANNEL_LENGHT - 1 DOWNTO 0);
s_axis_tlast : IN STD_LOGIC;
s_axis_tready : OUT STD_LOGIC
-- LED output array (bar graph display)
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
);
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;
SIGNAL volume_value : signed(CHANNEL_LENGHT - 1 DOWNTO 0) := (OTHERS => '0');
SIGNAL abs_audio_left : unsigned(CHANNEL_LENGHT - 2 DOWNTO 0) := (OTHERS => '0');
SIGNAL abs_audio_right : unsigned(CHANNEL_LENGHT - 2 DOWNTO 0) := (OTHERS => '0');
SIGNAL leds_int : STD_LOGIC_VECTOR(NUM_LEDS - 1 DOWNTO 0) := (OTHERS => '0');
SIGNAL led_update : STD_LOGIC := '0';
SIGNAL refresh_counter : NATURAL RANGE 0 TO REFRESH_CYCLES - 1 := 0;
-- 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 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
BEGIN
led <= leds_int;
s_axis_tready <= '1';
-- Registering the absolute audio value
-- 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)
-- Audio sample processing and absolute value calculation
-- Converts signed audio samples to unsigned absolute values for level detection
PROCESS (aclk)
VARIABLE sdata_signed : signed(CHANNEL_LENGHT - 1 DOWNTO 0);
VARIABLE abs_value : unsigned(CHANNEL_LENGHT - 1 DOWNTO 0);
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
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
volume_value <= (OTHERS => '0');
abs_audio_left <= (OTHERS => '0');
abs_audio_right <= (OTHERS => '0');
-- 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
ELSIF s_axis_tvalid = '1' THEN
sdata_signed := signed(s_axis_tdata);
volume_value <= sdata_signed;
-- Absolute value calculation
-- 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
-- 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;
-- Assign to the correct channel
IF s_axis_tlast = '1' THEN -- Left channel
-- Channel assignment based on tlast signal
-- Note: Channel assignment appears reversed from typical convention
IF s_axis_tlast = '1' THEN
-- tlast = '1': Assign to left channel
abs_audio_left <= abs_value(CHANNEL_LENGHT - 2 DOWNTO 0);
ELSE -- Right channel
ELSE
-- tlast = '0': Assign to right channel
abs_audio_right <= abs_value(CHANNEL_LENGHT - 2 DOWNTO 0);
END IF;
END IF;
END IF;
END PROCESS;
-- Refresh counter
-- LED refresh timing control
-- Generates periodic update signals for smooth LED display updates
PROCESS (aclk)
BEGIN
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
refresh_counter <= 0;
led_update <= '0';
-- Reset timing control
refresh_counter <= 0; -- Clear refresh counter
led_update <= '0'; -- Clear update trigger
ELSIF refresh_counter = REFRESH_CYCLES - 1 THEN
refresh_counter <= 0;
led_update <= '1';
-- End of refresh period: Trigger LED update
refresh_counter <= 0; -- Reset counter for next period
led_update <= '1'; -- Set update trigger
ELSE
refresh_counter <= refresh_counter + 1;
led_update <= '0';
-- Continue counting refresh period
refresh_counter <= refresh_counter + 1; -- Increment counter
led_update <= '0'; -- Clear update trigger
END IF;
END IF;
END PROCESS;
-- Linear scaling and LED update
-- LED level calculation and bar graph generation
-- Combines left and right channel levels and maps to LED array
PROCESS (aclk)
VARIABLE leds_on : NATURAL RANGE 0 TO NUM_LEDS;
VARIABLE temp_led_level : INTEGER RANGE 0 TO NUM_LEDS;
VARIABLE abs_audio_sum : unsigned(CHANNEL_LENGHT - 1 DOWNTO 0);
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
BEGIN
IF rising_edge(aclk) THEN
IF aresetn = '0' THEN
-- Reset: Turn off all LEDs
leds_int <= (OTHERS => '0');
ELSIF led_update = '1' THEN
-- Update LED display when refresh trigger is active
-- 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);
-- 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
-- Automatic scaling
-- Sensitivity can be adjusted by changing the shift constant
-- 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));
END IF;
-- Limit to the maximum number of LEDs
-- Limit LED level to available LEDs (prevent array overflow)
IF temp_led_level > NUM_LEDS THEN
leds_on := NUM_LEDS;
leds_on := NUM_LEDS; -- Cap at maximum LEDs
ELSE
leds_on := temp_led_level;
leds_on := temp_led_level; -- Use calculated level
END IF;
-- Update the LEDs
leds_int <= (OTHERS => '0');
-- 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;