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SAI example with wolfson wm8960 codec
Provides a sample application for playing back audio without DMA directly writing to the FIFO of the SAI peripheral, which should result in an I2S signaling to the WM8960 codec on the EVK boards. The codec should then output a nice square wave on one channel and a sine wave on the other. The example in this case uses a PIT timer to print the status and a SAI1 interrupt noting a FIFO request to synthesize samples when needed.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,204 @@ | ||
| //! Audio playback using sai peripheral and imxrt-hal. | ||
| //! | ||
| //! Plays back a simple 440Hz (A note) simple square wave tone with the SAI peripheral | ||
| //! to a Wolfson WM8960 codec on a number of the EVK boards. | ||
| //! | ||
| //! The audio stream itself is expected to be a 48000Hz 16bit stereo signal. | ||
|
|
||
| #![no_main] | ||
| #![no_std] | ||
|
|
||
| /// Half of a sine wave (0 to pi) | ||
| /// Can be used to generate a full sine wave by inverting (-1 * SIN_LUT[X]); | ||
| const SIN_LUT: [u16; 256] = [ | ||
| 0, 402, 804, 1206, 1608, 2009, 2411, 2811, 3212, 3612, 4011, 4410, 4808, 5205, 5602, 5998, | ||
| 6393, 6787, 7180, 7571, 7962, 8351, 8740, 9127, 9512, 9896, 10279, 10660, 11039, 11417, 11793, | ||
| 12167, 12540, 12910, 13279, 13646, 14010, 14373, 14733, 15091, 15447, 15800, 16151, 16500, | ||
| 16846, 17190, 17531, 17869, 18205, 18538, 18868, 19195, 19520, 19841, 20160, 20475, 20788, | ||
| 21097, 21403, 21706, 22006, 22302, 22595, 22884, 23170, 23453, 23732, 24008, 24279, 24548, | ||
| 24812, 25073, 25330, 25583, 25833, 26078, 26320, 26557, 26791, 27020, 27246, 27467, 27684, | ||
| 27897, 28106, 28311, 28511, 28707, 28899, 29086, 29269, 29448, 29622, 29792, 29957, 30118, | ||
| 30274, 30425, 30572, 30715, 30853, 30986, 31114, 31238, 31357, 31471, 31581, 31686, 31786, | ||
| 31881, 31972, 32058, 32138, 32214, 32286, 32352, 32413, 32470, 32522, 32568, 32610, 32647, | ||
| 32679, 32706, 32729, 32746, 32758, 32766, 32767, 32766, 32758, 32746, 32729, 32706, 32679, | ||
| 32647, 32610, 32568, 32522, 32470, 32413, 32352, 32286, 32214, 32138, 32058, 31972, 31881, | ||
| 31786, 31686, 31581, 31471, 31357, 31238, 31114, 30986, 30853, 30715, 30572, 30425, 30274, | ||
| 30118, 29957, 29792, 29622, 29448, 29269, 29086, 28899, 28707, 28511, 28311, 28106, 27897, | ||
| 27684, 27467, 27246, 27020, 26791, 26557, 26320, 26078, 25833, 25583, 25330, 25073, 24812, | ||
| 24548, 24279, 24008, 23732, 23453, 23170, 22884, 22595, 22302, 22006, 21706, 21403, 21097, | ||
| 20788, 20475, 20160, 19841, 19520, 19195, 18868, 18538, 18205, 17869, 17531, 17190, 16846, | ||
| 16500, 16151, 15800, 15447, 15091, 14733, 14373, 14010, 13646, 13279, 12910, 12540, 12167, | ||
| 11793, 11417, 11039, 10660, 10279, 9896, 9512, 9127, 8740, 8351, 7962, 7571, 7180, 6787, 6393, | ||
| 5998, 5602, 5205, 4808, 4410, 4011, 3612, 3212, 2811, 2411, 2009, 1608, 1206, 804, 402, | ||
| ]; | ||
|
|
||
| /// Generate a sine wave sample | ||
| fn sine(t: u32) -> u16 { | ||
| let p = t % 512; | ||
| let s = SIN_LUT[(p % 256) as usize]; | ||
| if p < 256 { | ||
| (32768 + s) / 2 | ||
| } else { | ||
| (32768 - s) / 2 | ||
| } | ||
| } | ||
|
|
||
| /// Generate a square wave sample | ||
| fn square(t: u32) -> u16 { | ||
| if (t % 128) > 64 { | ||
| 32767 | ||
| } else { | ||
| 0 | ||
| } | ||
| } | ||
|
|
||
| #[rtic::app(device = board, peripherals = false, dispatchers = [BOARD_SWTASK0])] | ||
| mod app { | ||
|
|
||
| // | ||
| // Configure the demo below. | ||
| // | ||
|
|
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| /// How frequently (milliseconds) should we poll audio | ||
| const AUDIO_POLL_MS: u32 = 1000 * (board::PIT_FREQUENCY / 1_000); | ||
|
|
||
| use crate::{sine, square}; | ||
| use imxrt_hal as hal; | ||
| use wm8960::WM8960; | ||
|
|
||
| type SaiTx = hal::sai::Tx<1, 16, 2, hal::sai::PackingNone>; | ||
|
|
||
| // | ||
| // End configurations. | ||
| // | ||
|
|
||
| #[local] | ||
| struct Local { | ||
| /// Toggle when we poll. | ||
| _led: board::Led, | ||
|
|
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| /// i2c for codec | ||
| _wm8960: WM8960<board::I2c>, | ||
|
|
||
| /// This timer tells us how frequently work on audio. | ||
| audio_pit: hal::pit::Pit<2>, | ||
|
|
||
| /// Sample counter for the wave generation | ||
| counter: u32, | ||
| } | ||
|
|
||
| #[shared] | ||
| struct Shared { | ||
| /// Serial audio interface | ||
| sai1_tx: SaiTx, | ||
| } | ||
|
|
||
| #[init] | ||
| fn init(cx: init::Context) -> (Shared, Local) { | ||
| let mut cortex_m = cx.core; | ||
| let ( | ||
| board::Common { | ||
| pit: (_, _, mut audio_pit, _), | ||
| .. | ||
| }, | ||
| board::Specifics { led, sai1, i2c, .. }, | ||
| ) = board::new(); | ||
| let (Some(sai1_tx), None) = sai1.split(&hal::sai::SaiConfig::i2s(hal::sai::bclk_div(8))) | ||
| else { | ||
| panic!("Unexpected return from sai split"); | ||
| }; | ||
|
|
||
| let mut sai1_tx: SaiTx = sai1_tx; | ||
|
|
||
| let regs = sai1_tx.reg_dump(); | ||
| defmt::println!( | ||
| "Regdump of config: TCR1: {:b}, TCR2 {:b}, TCR3 {:b}, TCR4 {:b}, TCR5 {:b}", | ||
| regs[0], | ||
| regs[1], | ||
| regs[2], | ||
| regs[3], | ||
| regs[4] | ||
| ); | ||
|
|
||
| cortex_m.DCB.enable_trace(); | ||
| cortex_m::peripheral::DWT::unlock(); | ||
| cortex_m.DWT.enable_cycle_counter(); | ||
|
|
||
| audio_pit.set_load_timer_value(AUDIO_POLL_MS); | ||
| audio_pit.set_interrupt_enable(true); | ||
| audio_pit.enable(); | ||
|
|
||
| let codec_cfg = wm8960::Config { | ||
| master: false, | ||
| format: wm8960::Format { | ||
| mclk_freq: 24_576_000, | ||
| sample_rate: wm8960::SampleRate::SR48000, | ||
| bit_width: wm8960::BitWidth::BW16, | ||
| }, | ||
| protocol: wm8960::Protocol::I2S, | ||
| route: wm8960::Route::Playback, | ||
| sysclk: wm8960::Sysclk { | ||
| source: wm8960::SysclkSource::Mclk, | ||
| freq: 0, | ||
| }, | ||
| speaker_en: true, | ||
| }; | ||
|
|
||
| let wm8960 = WM8960::new(i2c, &codec_cfg).unwrap(); | ||
|
|
||
| let mut counter: u32 = 0; | ||
| for _i in 0..31 { | ||
| sai1_tx.write_frame(0, [sine(counter), square(counter)]); | ||
| counter += 1; | ||
| } | ||
| sai1_tx.set_interrupts( | ||
| hal::sai::Interrupts::FIFO_WARNING | hal::sai::Interrupts::FIFO_REQUEST, | ||
| ); | ||
| sai1_tx.set_enable(true); | ||
| ( | ||
| Shared { sai1_tx }, | ||
| Local { | ||
| _led: led, | ||
| _wm8960: wm8960, | ||
| audio_pit, | ||
| counter, | ||
| }, | ||
| ) | ||
| } | ||
|
|
||
| #[task(binds = BOARD_SAI1, shared = [sai1_tx], local = [counter], priority = 2)] | ||
| fn sai1_interrupt(mut cx: sai1_interrupt::Context) { | ||
| let sai1_interrupt::LocalResources { counter, .. } = cx.local; | ||
|
|
||
| cx.shared.sai1_tx.lock(|sai1_tx| { | ||
| while sai1_tx.status().contains(hal::sai::Status::FIFO_REQUEST) { | ||
| sai1_tx.write_frame(0, [sine(*counter), square(*counter)]); | ||
| *counter = (*counter).wrapping_add(1); | ||
| } | ||
| }); | ||
| } | ||
|
|
||
| #[task(binds = BOARD_PIT, shared = [sai1_tx], local = [audio_pit], priority = 1)] | ||
| fn pit_interrupt(mut cx: pit_interrupt::Context) { | ||
| let pit_interrupt::LocalResources { audio_pit, .. } = cx.local; | ||
|
|
||
| //led.toggle(); | ||
| while audio_pit.is_elapsed() { | ||
| audio_pit.clear_elapsed(); | ||
| } | ||
|
|
||
| let (status, write_pos, read_pos) = cx.shared.sai1_tx.lock(|sai1_tx| { | ||
| let status = sai1_tx.status(); | ||
| let (write_pos, read_pos) = sai1_tx.fifo_position(0); | ||
| (status, write_pos, read_pos) | ||
| }); | ||
|
|
||
| defmt::println!( | ||
| "Audio synthesis tx status {:#x}, fifo underrun? {}, write pos {}, read pos {}", | ||
| status.bits(), | ||
| status.contains(hal::sai::Status::FIFO_ERROR), | ||
| write_pos, | ||
| read_pos, | ||
| ); | ||
| } | ||
| } |