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refactor: Improve code readability and organization in led_level_controller.vhd

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This commit is contained in:
Davide Cavagnola
2025-05-31 19:23:45 +02:00
parent c66c218f65
commit a52023733d
1 changed files with 85 additions and 114 deletions
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LAB3/src/led_level_controller.vhd
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@@ -8,175 +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 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
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
-- 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 s_axis_tdata(s_axis_tdata'high) = '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
abs_audio_sum := abs_audio_left + abs_audio_right;
-- 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 linear scaling to get the best visual result
IF abs_audio_sum = 0 THEN
-- Mute: No LEDs illuminated
temp_led_level := 0;
ELSE
-- Right shift by (CHANNEL_LENGHT - 4) to take in account only the most significant bits
-- to scale the audio amplitude in a linear way to fit within the LED range
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;
END Behavioral;