From 9d57ca253d2242c729cfcc78b60d648d64f543f4 Mon Sep 17 00:00:00 2001 From: elagil Date: Sat, 2 Nov 2024 20:01:20 +0100 Subject: [PATCH] feat(stm32f4): add usb audio example --- examples/stm32f4/Cargo.toml | 1 + examples/stm32f4/src/bin/usb_uac_speaker.rs | 375 ++++++++++++++++++++ 2 files changed, 376 insertions(+) create mode 100644 examples/stm32f4/src/bin/usb_uac_speaker.rs diff --git a/examples/stm32f4/Cargo.toml b/examples/stm32f4/Cargo.toml index 975e47398..900322563 100644 --- a/examples/stm32f4/Cargo.toml +++ b/examples/stm32f4/Cargo.toml @@ -27,6 +27,7 @@ embedded-io-async = { version = "0.6.1" } panic-probe = { version = "0.3", features = ["print-defmt"] } futures-util = { version = "0.3.30", default-features = false } heapless = { version = "0.8", default-features = false } +critical-section = "1.1" nb = "1.0.0" embedded-storage = "0.3.1" micromath = "2.0.0" diff --git a/examples/stm32f4/src/bin/usb_uac_speaker.rs b/examples/stm32f4/src/bin/usb_uac_speaker.rs new file mode 100644 index 000000000..77c693ace --- /dev/null +++ b/examples/stm32f4/src/bin/usb_uac_speaker.rs @@ -0,0 +1,375 @@ +#![no_std] +#![no_main] + +use core::cell::RefCell; + +use defmt::{panic, *}; +use embassy_executor::Spawner; +use embassy_stm32::time::Hertz; +use embassy_stm32::{bind_interrupts, interrupt, peripherals, timer, usb, Config}; +use embassy_sync::blocking_mutex::raw::{CriticalSectionRawMutex, NoopRawMutex}; +use embassy_sync::blocking_mutex::Mutex; +use embassy_sync::signal::Signal; +use embassy_sync::zerocopy_channel; +use embassy_usb::class::uac1; +use embassy_usb::class::uac1::speaker::{self, Speaker}; +use embassy_usb::driver::EndpointError; +use heapless::Vec; +use micromath::F32Ext; +use static_cell::StaticCell; +use {defmt_rtt as _, panic_probe as _}; + +bind_interrupts!(struct Irqs { + OTG_FS => usb::InterruptHandler; +}); + +static TIMER: Mutex>>> = + Mutex::new(RefCell::new(None)); + +// A counter signal that is written by the feedback timer, once every `FEEDBACK_REFRESH_PERIOD`. +// At that point, a feedback value is sent to the host. +pub static FEEDBACK_SIGNAL: Signal = Signal::new(); + +// Stereo input +pub const INPUT_CHANNEL_COUNT: usize = 2; + +// This example uses a fixed sample rate of 48 kHz. +pub const SAMPLE_RATE_HZ: u32 = 48_000; +pub const FEEDBACK_COUNTER_TICK_RATE: u32 = 42_000_000; + +// Use 32 bit samples, which allow for a lot of (software) volume adjustment without degradation of quality. +pub const SAMPLE_WIDTH: uac1::SampleWidth = uac1::SampleWidth::Width4Byte; +pub const SAMPLE_WIDTH_BIT: usize = SAMPLE_WIDTH.in_bit(); +pub const SAMPLE_SIZE: usize = SAMPLE_WIDTH as usize; +pub const SAMPLE_SIZE_PER_S: usize = (SAMPLE_RATE_HZ as usize) * INPUT_CHANNEL_COUNT * SAMPLE_SIZE; + +// Size of audio samples per 1 ms - for the full-speed USB frame period of 1 ms. +pub const USB_FRAME_SIZE: usize = SAMPLE_SIZE_PER_S.div_ceil(1000); + +// Select front left and right audio channels. +pub const AUDIO_CHANNELS: [uac1::Channel; INPUT_CHANNEL_COUNT] = [uac1::Channel::LeftFront, uac1::Channel::RightFront]; + +// Factor of two as a margin for feedback (this is an excessive amount) +pub const USB_MAX_PACKET_SIZE: usize = 2 * USB_FRAME_SIZE; +pub const USB_MAX_SAMPLE_COUNT: usize = USB_MAX_PACKET_SIZE / SAMPLE_SIZE; + +// The data type that is exchanged via the zero-copy channel (a sample vector). +pub type SampleBlock = Vec; + +// Feedback is provided in 10.14 format for full-speed endpoints. +pub const FEEDBACK_REFRESH_PERIOD: uac1::FeedbackRefresh = uac1::FeedbackRefresh::Period8Frames; +const FEEDBACK_SHIFT: usize = 14; + +const TICKS_PER_SAMPLE: f32 = (FEEDBACK_COUNTER_TICK_RATE as f32) / (SAMPLE_RATE_HZ as f32); + +struct Disconnected {} + +impl From for Disconnected { + fn from(val: EndpointError) -> Self { + match val { + EndpointError::BufferOverflow => panic!("Buffer overflow"), + EndpointError::Disabled => Disconnected {}, + } + } +} + +/// Sends feedback messages to the host. +async fn feedback_handler<'d, T: usb::Instance + 'd>( + feedback: &mut speaker::Feedback<'d, usb::Driver<'d, T>>, + feedback_factor: f32, +) -> Result<(), Disconnected> { + let mut packet: Vec = Vec::new(); + + // Collects the fractional component of the feedback value that is lost by rounding. + let mut rest = 0.0_f32; + + loop { + let counter = FEEDBACK_SIGNAL.wait().await; + + packet.clear(); + + let raw_value = counter as f32 * feedback_factor + rest; + let value = raw_value.round(); + rest = raw_value - value; + + let value = value as u32; + packet.push(value as u8).unwrap(); + packet.push((value >> 8) as u8).unwrap(); + packet.push((value >> 16) as u8).unwrap(); + + feedback.write_packet(&packet).await?; + } +} + +/// Handles streaming of audio data from the host. +async fn stream_handler<'d, T: usb::Instance + 'd>( + stream: &mut speaker::Stream<'d, usb::Driver<'d, T>>, + sender: &mut zerocopy_channel::Sender<'static, NoopRawMutex, SampleBlock>, +) -> Result<(), Disconnected> { + loop { + let mut usb_data = [0u8; USB_MAX_PACKET_SIZE]; + let data_size = stream.read_packet(&mut usb_data).await?; + + let word_count = data_size / SAMPLE_SIZE; + + if word_count * SAMPLE_SIZE == data_size { + // Obtain a buffer from the channel + let samples = sender.send().await; + samples.clear(); + + for w in 0..word_count { + let byte_offset = w * SAMPLE_SIZE; + let sample = u32::from_le_bytes(usb_data[byte_offset..byte_offset + SAMPLE_SIZE].try_into().unwrap()); + + // Fill the sample buffer with data. + samples.push(sample).unwrap(); + } + + sender.send_done(); + } else { + debug!("Invalid USB buffer size of {}, skipped.", data_size); + } + } +} + +/// Receives audio samples from the USB streaming task and can play them back. +#[embassy_executor::task] +async fn audio_receiver_task(mut usb_audio_receiver: zerocopy_channel::Receiver<'static, NoopRawMutex, SampleBlock>) { + loop { + let _samples = usb_audio_receiver.receive().await; + // Use the samples, for example play back via the SAI peripheral. + + // Notify the channel that the buffer is now ready to be reused + usb_audio_receiver.receive_done(); + } +} + +/// Receives audio samples from the host. +#[embassy_executor::task] +async fn usb_streaming_task( + mut stream: speaker::Stream<'static, usb::Driver<'static, peripherals::USB_OTG_FS>>, + mut sender: zerocopy_channel::Sender<'static, NoopRawMutex, SampleBlock>, +) { + loop { + stream.wait_connection().await; + _ = stream_handler(&mut stream, &mut sender).await; + } +} + +/// Sends sample rate feedback to the host. +/// +/// The `feedback_factor` scales the feedback timer's counter value so that the result is the number of samples that +/// this device played back or "consumed" during one SOF period (1 ms) - in 10.14 format. +/// +/// Ideally, the `feedback_factor` that is calculated below would be an integer for avoiding numerical errors. +/// This is achieved by having `TICKS_PER_SAMPLE` be a power of two. For audio applications at a sample rate of 48 kHz, +/// 24.576 MHz would be one such option. +/// +/// A good choice for the STM32F4, which also has to generate a 48 MHz clock from its HSE (e.g. running at 8 MHz) +/// for USB, is to clock the feedback timer from the MCLK output of the SAI peripheral. The SAI peripheral then uses an +/// external clock. In that case, wiring the MCLK output to the timer clock input is required. +/// +/// This simple example just uses the internal clocks for supplying the feedback timer, +/// and does not even set up a SAI peripheral. +#[embassy_executor::task] +async fn usb_feedback_task(mut feedback: speaker::Feedback<'static, usb::Driver<'static, peripherals::USB_OTG_FS>>) { + let feedback_factor = + ((1 << FEEDBACK_SHIFT) as f32 / TICKS_PER_SAMPLE) / FEEDBACK_REFRESH_PERIOD.frame_count() as f32; + + // Should be 2.3405714285714287... + info!("Using a feedback factor of {}.", feedback_factor); + + loop { + feedback.wait_connection().await; + _ = feedback_handler(&mut feedback, feedback_factor).await; + } +} + +#[embassy_executor::task] +async fn usb_task(mut usb_device: embassy_usb::UsbDevice<'static, usb::Driver<'static, peripherals::USB_OTG_FS>>) { + usb_device.run().await; +} + +/// Checks for changes on the control monitor of the class. +/// +/// In this case, monitor changes of volume or mute state. +#[embassy_executor::task] +async fn usb_control_task(control_monitor: speaker::ControlMonitor<'static>) { + loop { + control_monitor.changed().await; + + for channel in AUDIO_CHANNELS { + let volume = control_monitor.volume(channel).unwrap(); + info!("Volume changed to {} on channel {}.", volume, channel); + } + } +} + +/// Feedback value measurement and calculation +/// +/// Used for measuring/calculating the number of samples that were received from the host during the +/// `FEEDBACK_REFRESH_PERIOD`. +/// +/// Configured in this example with +/// - a refresh period of 8 ms, and +/// - a tick rate of 42 MHz. +/// +/// This gives an (ideal) counter value of 336.000 for every update of the `FEEDBACK_SIGNAL`. +#[interrupt] +fn TIM2() { + static mut LAST_TICKS: u32 = 0; + static mut FRAME_COUNT: usize = 0; + + critical_section::with(|cs| { + // Read timer counter. + let ticks = TIMER.borrow(cs).borrow().as_ref().unwrap().regs_gp32().cnt().read(); + + // Clear trigger interrupt flag. + TIMER + .borrow(cs) + .borrow_mut() + .as_mut() + .unwrap() + .regs_gp32() + .sr() + .modify(|r| r.set_tif(false)); + + // Count up frames and emit a signal, when the refresh period is reached (here, every 8 ms). + *FRAME_COUNT += 1; + if *FRAME_COUNT >= FEEDBACK_REFRESH_PERIOD.frame_count() { + *FRAME_COUNT = 0; + FEEDBACK_SIGNAL.signal(ticks.wrapping_sub(*LAST_TICKS)); + *LAST_TICKS = ticks; + } + }); +} + +// If you are trying this and your USB device doesn't connect, the most +// common issues are the RCC config and vbus_detection +// +// See https://embassy.dev/book/#_the_usb_examples_are_not_working_on_my_board_is_there_anything_else_i_need_to_configure +// for more information. +#[embassy_executor::main] +async fn main(spawner: Spawner) { + info!("Hello World!"); + + let mut config = Config::default(); + { + use embassy_stm32::rcc::*; + config.rcc.hse = Some(Hse { + freq: Hertz(8_000_000), + mode: HseMode::Bypass, + }); + config.rcc.pll_src = PllSource::HSE; + config.rcc.pll = Some(Pll { + prediv: PllPreDiv::DIV4, + mul: PllMul::MUL168, + divp: Some(PllPDiv::DIV2), // ((8 MHz / 4) * 168) / 2 = 168 Mhz. + divq: Some(PllQDiv::DIV7), // ((8 MHz / 4) * 168) / 7 = 48 Mhz. + divr: None, + }); + config.rcc.ahb_pre = AHBPrescaler::DIV1; + config.rcc.apb1_pre = APBPrescaler::DIV4; + config.rcc.apb2_pre = APBPrescaler::DIV2; + config.rcc.sys = Sysclk::PLL1_P; + config.rcc.mux.clk48sel = mux::Clk48sel::PLL1_Q; + } + let p = embassy_stm32::init(config); + + // Configure all required buffers in a static way. + debug!("USB packet size is {} byte", USB_MAX_PACKET_SIZE); + static CONFIG_DESCRIPTOR: StaticCell<[u8; 256]> = StaticCell::new(); + let config_descriptor = CONFIG_DESCRIPTOR.init([0; 256]); + + static BOS_DESCRIPTOR: StaticCell<[u8; 32]> = StaticCell::new(); + let bos_descriptor = BOS_DESCRIPTOR.init([0; 32]); + + const CONTROL_BUF_SIZE: usize = 64; + static CONTROL_BUF: StaticCell<[u8; CONTROL_BUF_SIZE]> = StaticCell::new(); + let control_buf = CONTROL_BUF.init([0; CONTROL_BUF_SIZE]); + + const FEEDBACK_BUF_SIZE: usize = 4; + static EP_OUT_BUFFER: StaticCell<[u8; FEEDBACK_BUF_SIZE + CONTROL_BUF_SIZE + USB_MAX_PACKET_SIZE]> = + StaticCell::new(); + let ep_out_buffer = EP_OUT_BUFFER.init([0u8; FEEDBACK_BUF_SIZE + CONTROL_BUF_SIZE + USB_MAX_PACKET_SIZE]); + + static STATE: StaticCell = StaticCell::new(); + let state = STATE.init(speaker::State::new()); + + // Create the driver, from the HAL. + let mut usb_config = usb::Config::default(); + + // Do not enable vbus_detection. This is a safe default that works in all boards. + // However, if your USB device is self-powered (can stay powered on if USB is unplugged), you need + // to enable vbus_detection to comply with the USB spec. If you enable it, the board + // has to support it or USB won't work at all. See docs on `vbus_detection` for details. + usb_config.vbus_detection = false; + + let usb_driver = usb::Driver::new_fs(p.USB_OTG_FS, Irqs, p.PA12, p.PA11, ep_out_buffer, usb_config); + + // Basic USB device configuration + let mut config = embassy_usb::Config::new(0xc0de, 0xcafe); + config.manufacturer = Some("Embassy"); + config.product = Some("USB-audio-speaker example"); + config.serial_number = Some("12345678"); + + // Required for windows compatibility. + // https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/kconfig/CONFIG_CDC_ACM_IAD.html#help + config.device_class = 0xEF; + config.device_sub_class = 0x02; + config.device_protocol = 0x01; + config.composite_with_iads = true; + + let mut builder = embassy_usb::Builder::new( + usb_driver, + config, + config_descriptor, + bos_descriptor, + &mut [], // no msos descriptors + control_buf, + ); + + // Create the UAC1 Speaker class components + let (stream, feedback, control_monitor) = Speaker::new( + &mut builder, + state, + USB_MAX_PACKET_SIZE as u16, + uac1::SampleWidth::Width4Byte, + &[SAMPLE_RATE_HZ], + &AUDIO_CHANNELS, + FEEDBACK_REFRESH_PERIOD, + ); + + // Create the USB device + let usb_device = builder.build(); + + // Establish a zero-copy channel for transferring received audio samples between tasks + static SAMPLE_BLOCKS: StaticCell<[SampleBlock; 2]> = StaticCell::new(); + let sample_blocks = SAMPLE_BLOCKS.init([Vec::new(), Vec::new()]); + + static CHANNEL: StaticCell> = StaticCell::new(); + let channel = CHANNEL.init(zerocopy_channel::Channel::new(sample_blocks)); + let (sender, receiver) = channel.split(); + + // Run a timer for counting between SOF interrupts. + let mut tim2 = timer::low_level::Timer::new(p.TIM2); + tim2.set_tick_freq(Hertz(FEEDBACK_COUNTER_TICK_RATE)); + tim2.set_trigger_source(timer::low_level::TriggerSource::ITR1); // The USB SOF signal. + tim2.set_slave_mode(timer::low_level::SlaveMode::TRIGGER_MODE); + tim2.regs_gp16().dier().modify(|r| r.set_tie(true)); // Enable the trigger interrupt. + tim2.start(); + + TIMER.lock(|p| p.borrow_mut().replace(tim2)); + + // Unmask the TIM2 interrupt. + unsafe { + cortex_m::peripheral::NVIC::unmask(interrupt::TIM2); + } + + // Launch USB audio tasks. + unwrap!(spawner.spawn(usb_control_task(control_monitor))); + unwrap!(spawner.spawn(usb_streaming_task(stream, sender))); + unwrap!(spawner.spawn(usb_feedback_task(feedback))); + unwrap!(spawner.spawn(usb_task(usb_device))); + unwrap!(spawner.spawn(audio_receiver_task(receiver))); +}