Add TDM support to I2S (#1673)
Fixes #1066 Implements a simple TDM mode for the I2S output object.
This commit is contained in:
Earle F. Philhower, III
GitHub
parent
1393811525
commit
e9daaa3589
7 changed files with 231 additions and 5 deletions
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@ -81,6 +81,15 @@ Enables LSB-J format for I2S output. In this mode the MSB comes out at the
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same time as the LRCLK changes, and not the normal 1-cycle delay. Useful for
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DAC chips like the PT8211.
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bool setTDMFormat()
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~~~~~~~~~~~~~~~~~~~
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Enabled TDM formatted multi-channel output. Be sure to set the number of channels to
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the expected value (8 normally) and the bits per sample to 32.
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bool setTDMChannels(int channels)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Sets the number of TDM channels between frame syncs. Generally should be set to 8.
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bool swapClocks()
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~~~~~~~~~~~~~~~~~
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Certain boards are hardwired with the WCLK before the BCLK, instead of the normal
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49
libraries/I2S/examples/TDM/TDM.ino
Normal file
49
libraries/I2S/examples/TDM/TDM.ino
Normal file
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@ -0,0 +1,49 @@
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/*
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This example just sends out TDM data on 8 channels with their value
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equal to the channel number.
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Released to the public domain by Earle F. Philhower, III <earlephilhower@yahoo.com>
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*/
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#include <I2S.h>
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// Create the I2S port using a PIO state machine
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I2S i2s(OUTPUT);
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// GPIO pin numbers
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#define pBCLK 20
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#define pWS (pBCLK+1)
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#define pDOUT 22
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const int sampleRate = 1000;
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void setup() {
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pinMode(LED_BUILTIN, OUTPUT);
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digitalWrite(LED_BUILTIN, 1);
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Serial.begin(115200);
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Serial.println("I2S TDM test");
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i2s.setBCLK(pBCLK);
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i2s.setDATA(pDOUT);
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i2s.setBitsPerSample(32);
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i2s.setTDMFormat();
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i2s.setTDMChannels(8);
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// start I2S at the sample rate with 16-bits per sample
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if (!i2s.begin(sampleRate)) {
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Serial.println("Failed to initialize I2S!");
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while (1); // do nothing
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}
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}
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void loop() {
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uint32_t x = 0;
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while (1) {
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i2s.write(x & 0x07);
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if (!(x % 10000)) {
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Serial.println(x);
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}
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x++;
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}
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}
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@ -21,6 +21,8 @@ setBitsPerSample KEYWORD2
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setFrequency KEYWORD2
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setBuffers KEYWORD2
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setLSBJFormat KEYWORD2
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setTDMFormat KEYWORD2
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setTDMChannels KEYWORD2
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swapClocks KEYWORD2
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setMCLKmult KEYWORD2
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setSysClk KEYWORD2
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@ -55,6 +55,8 @@ I2S::I2S(PinMode direction) {
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_bufferWords = 0;
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_silenceSample = 0;
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_isLSBJ = false;
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_isTDM = false;
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_tdmChannels = 8;
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_swapClocks = false;
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_multMCLK = 256;
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}
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@ -109,10 +111,10 @@ bool I2S::setFrequency(int newFreq) {
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_freq = newFreq;
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if (_running) {
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if (_MCLKenabled) {
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int bitClk = _freq * _bps * 2.0 /* channels */ * 2.0 /* edges per clock */;
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int bitClk = _freq * _bps * (_isTDM ? (double)_tdmChannels : 2.0) /* channels */ * 2.0 /* edges per clock */;
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pio_sm_set_clkdiv_int_frac(_pio, _sm, clock_get_hz(clk_sys) / bitClk, 0);
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} else {
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float bitClk = _freq * _bps * 2.0 /* channels */ * 2.0 /* edges per clock */;
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float bitClk = _freq * _bps * (_isTDM ? (double)_tdmChannels : 2.0) /* channels */ * 2.0 /* edges per clock */;
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pio_sm_set_clkdiv(_pio, _sm, (float)clock_get_hz(clk_sys) / bitClk);
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}
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}
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@ -151,6 +153,22 @@ bool I2S::setLSBJFormat() {
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return true;
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}
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bool I2S::setTDMFormat() {
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if (_running || !_isOutput) {
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return false;
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}
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_isTDM = true;
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return true;
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}
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bool I2S::setTDMChannels(int channels) {
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if (_running || !_isOutput) {
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return false;
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}
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_tdmChannels = channels;
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return true;
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}
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bool I2S::swapClocks() {
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if (_running || !_isOutput) {
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return false;
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@ -193,9 +211,9 @@ bool I2S::begin() {
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_isHolding = 0;
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int off = 0;
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if (!_swapClocks) {
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_i2s = new PIOProgram(_isOutput ? (_isLSBJ ? &pio_lsbj_out_program : &pio_i2s_out_program) : &pio_i2s_in_program);
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_i2s = new PIOProgram(_isOutput ? (_isTDM ? &pio_tdm_out_program : (_isLSBJ ? &pio_lsbj_out_program : &pio_i2s_out_program)) : &pio_i2s_in_program);
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} else {
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_i2s = new PIOProgram(_isOutput ? (_isLSBJ ? &pio_lsbj_out_swap_program : &pio_i2s_out_swap_program) : &pio_i2s_in_swap_program);
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_i2s = new PIOProgram(_isOutput ? (_isTDM ? &pio_tdm_out_swap_program : (_isLSBJ ? &pio_lsbj_out_swap_program : &pio_i2s_out_swap_program)) : &pio_i2s_in_swap_program);
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}
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if (!_i2s->prepare(&_pio, &_sm, &off)) {
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_running = false;
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@ -204,7 +222,9 @@ bool I2S::begin() {
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return false;
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}
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if (_isOutput) {
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if (_isLSBJ) {
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if (_isTDM) {
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pio_tdm_out_program_init(_pio, _sm, off, _pinDOUT, _pinBCLK, _bps, _swapClocks, _tdmChannels);
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} else if (_isLSBJ) {
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pio_lsbj_out_program_init(_pio, _sm, off, _pinDOUT, _pinBCLK, _bps, _swapClocks);
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} else {
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pio_i2s_out_program_init(_pio, _sm, off, _pinDOUT, _pinBCLK, _bps, _swapClocks);
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@ -35,6 +35,8 @@ public:
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bool setBuffers(size_t buffers, size_t bufferWords, int32_t silenceSample = 0);
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bool setFrequency(int newFreq);
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bool setLSBJFormat();
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bool setTDMFormat();
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bool setTDMChannels(int channels);
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bool swapClocks();
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bool setMCLKmult(int mult);
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bool setSysClk(int samplerate);
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@ -121,6 +123,8 @@ private:
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size_t _bufferWords;
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int32_t _silenceSample;
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bool _isLSBJ;
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bool _isTDM;
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int _tdmChannels;
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bool _isOutput;
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bool _swapClocks;
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bool _MCLKenabled;
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@ -72,6 +72,38 @@ right:
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; Loop back to beginning...
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.program pio_tdm_out
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.side_set 2 ; 0 = bclk, 1 = wclk
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; The C code should place (number of bits - 1) in Y and update SHIFTCTRL
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; to be 32 (as per the TDM specs)
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; +----- WCLK
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; |+---- BCLK
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mov x, y side 0b11
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bitloop:
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out pins, 1 side 0b00
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jmp x-- bitloop side 0b01
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lastbit:
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out pins, 1 side 0b10
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; Loop back to the beginning
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.program pio_tdm_out_swap
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.side_set 2 ; 0 = wclk, 1 = bclk
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; The C code should place (number of bits - 1) in Y and update SHIFTCTRL
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; to be 32 (as per the TDM specs)
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; +----- BCLK
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; |+---- WCLK
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mov x, y side 0b11
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bitloop:
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out pins, 1 side 0b00
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jmp x-- bitloop side 0b10
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lastbit:
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out pins, 1 side 0b01
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; Loop back to the beginning
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.program pio_lsbj_out
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.side_set 2 ; 0 = bclk, 1=wclk
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@ -195,6 +227,33 @@ static inline void pio_i2s_out_program_init(PIO pio, uint sm, uint offset, uint
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pio_sm_exec(pio, sm, pio_encode_set(pio_y, bits - 2));
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}
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static inline void pio_tdm_out_program_init(PIO pio, uint sm, uint offset, uint data_pin, uint clock_pin_base, uint bits, bool swap, uint channels) {
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pio_gpio_init(pio, data_pin);
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pio_gpio_init(pio, clock_pin_base);
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pio_gpio_init(pio, clock_pin_base + 1);
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pio_sm_config sm_config = swap ? pio_tdm_out_swap_program_get_default_config(offset) : pio_tdm_out_program_get_default_config(offset);
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sm_config_set_out_pins(&sm_config, data_pin, 1);
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sm_config_set_sideset_pins(&sm_config, clock_pin_base);
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sm_config_set_out_shift(&sm_config, false, true, 32);
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sm_config_set_fifo_join(&sm_config, PIO_FIFO_JOIN_TX);
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pio_sm_init(pio, sm, offset, &sm_config);
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uint pin_mask = (1u << data_pin) | (3u << clock_pin_base);
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pio_sm_set_pindirs_with_mask(pio, sm, pin_mask, pin_mask);
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pio_sm_set_pins(pio, sm, 0); // clear pins
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// Can't set constant > 31, so push and pop/mov
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pio_sm_put_blocking(pio, sm, bits * channels - 2);
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pio_sm_exec(pio, sm, pio_encode_pull(false, false));
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pio_sm_exec(pio, sm, pio_encode_mov(pio_y, pio_osr));
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// Need to make OSR believe there's nothing left to shift out, or the 1st word will be the count we just passed in, not a sample
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pio_sm_exec(pio, sm, pio_encode_out(pio_osr, 32));
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}
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static inline void pio_lsbj_out_program_init(PIO pio, uint sm, uint offset, uint data_pin, uint clock_pin_base, uint bits, bool swap) {
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pio_gpio_init(pio, data_pin);
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pio_gpio_init(pio, clock_pin_base);
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@ -106,6 +106,68 @@ static inline pio_sm_config pio_i2s_out_swap_program_get_default_config(uint off
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}
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#endif
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// ----------- //
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// pio_tdm_out //
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// ----------- //
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#define pio_tdm_out_wrap_target 0
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#define pio_tdm_out_wrap 3
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static const uint16_t pio_tdm_out_program_instructions[] = {
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// .wrap_target
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0xb822, // 0: mov x, y side 3
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0x6001, // 1: out pins, 1 side 0
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0x0841, // 2: jmp x--, 1 side 1
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0x7001, // 3: out pins, 1 side 2
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// .wrap
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};
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#if !PICO_NO_HARDWARE
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static const struct pio_program pio_tdm_out_program = {
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.instructions = pio_tdm_out_program_instructions,
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.length = 4,
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.origin = -1,
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};
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static inline pio_sm_config pio_tdm_out_program_get_default_config(uint offset) {
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pio_sm_config c = pio_get_default_sm_config();
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sm_config_set_wrap(&c, offset + pio_tdm_out_wrap_target, offset + pio_tdm_out_wrap);
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sm_config_set_sideset(&c, 2, false, false);
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return c;
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}
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#endif
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// ---------------- //
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// pio_tdm_out_swap //
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// ---------------- //
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#define pio_tdm_out_swap_wrap_target 0
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#define pio_tdm_out_swap_wrap 3
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static const uint16_t pio_tdm_out_swap_program_instructions[] = {
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// .wrap_target
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0xb822, // 0: mov x, y side 3
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0x6001, // 1: out pins, 1 side 0
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0x1041, // 2: jmp x--, 1 side 2
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0x6801, // 3: out pins, 1 side 1
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// .wrap
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};
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#if !PICO_NO_HARDWARE
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static const struct pio_program pio_tdm_out_swap_program = {
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.instructions = pio_tdm_out_swap_program_instructions,
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.length = 4,
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.origin = -1,
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};
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static inline pio_sm_config pio_tdm_out_swap_program_get_default_config(uint offset) {
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pio_sm_config c = pio_get_default_sm_config();
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sm_config_set_wrap(&c, offset + pio_tdm_out_swap_wrap_target, offset + pio_tdm_out_swap_wrap);
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sm_config_set_sideset(&c, 2, false, false);
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return c;
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}
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#endif
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// ------------ //
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// pio_lsbj_out //
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// ------------ //
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@ -267,6 +329,26 @@ static inline void pio_i2s_out_program_init(PIO pio, uint sm, uint offset, uint
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pio_sm_set_pins(pio, sm, 0); // clear pins
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pio_sm_exec(pio, sm, pio_encode_set(pio_y, bits - 2));
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}
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static inline void pio_tdm_out_program_init(PIO pio, uint sm, uint offset, uint data_pin, uint clock_pin_base, uint bits, bool swap, uint channels) {
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pio_gpio_init(pio, data_pin);
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pio_gpio_init(pio, clock_pin_base);
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pio_gpio_init(pio, clock_pin_base + 1);
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pio_sm_config sm_config = swap ? pio_tdm_out_swap_program_get_default_config(offset) : pio_tdm_out_program_get_default_config(offset);
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sm_config_set_out_pins(&sm_config, data_pin, 1);
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sm_config_set_sideset_pins(&sm_config, clock_pin_base);
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sm_config_set_out_shift(&sm_config, false, true, 32);
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sm_config_set_fifo_join(&sm_config, PIO_FIFO_JOIN_TX);
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pio_sm_init(pio, sm, offset, &sm_config);
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uint pin_mask = (1u << data_pin) | (3u << clock_pin_base);
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pio_sm_set_pindirs_with_mask(pio, sm, pin_mask, pin_mask);
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pio_sm_set_pins(pio, sm, 0); // clear pins
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// Can't set constant > 31, so push and pop/mov
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pio_sm_put_blocking(pio, sm, bits * channels - 2);
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pio_sm_exec(pio, sm, pio_encode_pull(false, false));
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pio_sm_exec(pio, sm, pio_encode_mov(pio_y, pio_osr));
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// Need to make OSR believe there's nothing left to shift out, or the 1st word will be the count we just passed in, not a sample
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pio_sm_exec(pio, sm, pio_encode_out(pio_osr, 32));
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}
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static inline void pio_lsbj_out_program_init(PIO pio, uint sm, uint offset, uint data_pin, uint clock_pin_base, uint bits, bool swap) {
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pio_gpio_init(pio, data_pin);
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pio_gpio_init(pio, clock_pin_base);
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@ -299,3 +381,4 @@ static inline void pio_i2s_in_program_init(PIO pio, uint sm, uint offset, uint d
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}
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#endif
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