From 3efc3eee5700d2a39e397f1b1b821885301c0862 Mon Sep 17 00:00:00 2001 From: Barnaby Walters Date: Mon, 20 Nov 2023 01:29:02 +0100 Subject: [PATCH] stm32/i2c: implement async i2c v1. --- embassy-stm32/src/i2c/v1.rs | 404 +++++++++++++++++++-- examples/stm32f4/src/bin/i2c_async.rs | 62 ++++ examples/stm32f4/src/bin/i2c_comparison.rs | 135 +++++++ 3 files changed, 578 insertions(+), 23 deletions(-) create mode 100644 examples/stm32f4/src/bin/i2c_async.rs create mode 100644 examples/stm32f4/src/bin/i2c_comparison.rs diff --git a/embassy-stm32/src/i2c/v1.rs b/embassy-stm32/src/i2c/v1.rs index 03f07c4f..b62ee824 100644 --- a/embassy-stm32/src/i2c/v1.rs +++ b/embassy-stm32/src/i2c/v1.rs @@ -1,10 +1,14 @@ +use core::future::poll_fn; use core::marker::PhantomData; +use core::task::Poll; use embassy_embedded_hal::SetConfig; +use embassy_futures::select::{select, Either}; +use embassy_hal_internal::drop::OnDrop; use embassy_hal_internal::{into_ref, PeripheralRef}; use super::*; -use crate::dma::NoDma; +use crate::dma::{NoDma, Transfer}; use crate::gpio::sealed::AFType; use crate::gpio::Pull; use crate::interrupt::typelevel::Interrupt; @@ -13,7 +17,17 @@ use crate::time::Hertz; use crate::{interrupt, Peripheral}; pub unsafe fn on_interrupt() { - // todo + let regs = T::regs(); + // i2c v2 only woke the task on transfer complete interrupts. v1 uses interrupts for a bunch of + // other stuff, so we wake the task on every interrupt. + T::state().waker.wake(); + critical_section::with(|_| { + // Clear event interrupt flag. + regs.cr2().modify(|w| { + w.set_itevten(false); + w.set_iterren(false); + }); + }); } #[non_exhaustive] @@ -98,40 +112,58 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> { } } - fn check_and_clear_error_flags(&self) -> Result { + fn check_and_clear_error_flags() -> Result { // Note that flags should only be cleared once they have been registered. If flags are // cleared otherwise, there may be an inherent race condition and flags may be missed. let sr1 = T::regs().sr1().read(); if sr1.timeout() { - T::regs().sr1().modify(|reg| reg.set_timeout(false)); + T::regs().sr1().write(|reg| { + reg.0 = !0; + reg.set_timeout(false); + }); return Err(Error::Timeout); } if sr1.pecerr() { - T::regs().sr1().modify(|reg| reg.set_pecerr(false)); + T::regs().sr1().write(|reg| { + reg.0 = !0; + reg.set_pecerr(false); + }); return Err(Error::Crc); } if sr1.ovr() { - T::regs().sr1().modify(|reg| reg.set_ovr(false)); + T::regs().sr1().write(|reg| { + reg.0 = !0; + reg.set_ovr(false); + }); return Err(Error::Overrun); } if sr1.af() { - T::regs().sr1().modify(|reg| reg.set_af(false)); + T::regs().sr1().write(|reg| { + reg.0 = !0; + reg.set_af(false); + }); return Err(Error::Nack); } if sr1.arlo() { - T::regs().sr1().modify(|reg| reg.set_arlo(false)); + T::regs().sr1().write(|reg| { + reg.0 = !0; + reg.set_arlo(false); + }); return Err(Error::Arbitration); } // The errata indicates that BERR may be incorrectly detected. It recommends ignoring and // clearing the BERR bit instead. if sr1.berr() { - T::regs().sr1().modify(|reg| reg.set_berr(false)); + T::regs().sr1().write(|reg| { + reg.0 = !0; + reg.set_berr(false); + }); } Ok(sr1) @@ -150,13 +182,13 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> { }); // Wait until START condition was generated - while !self.check_and_clear_error_flags()?.start() { + while !Self::check_and_clear_error_flags()?.start() { check_timeout()?; } // Also wait until signalled we're master and everything is waiting for us while { - self.check_and_clear_error_flags()?; + Self::check_and_clear_error_flags()?; let sr2 = T::regs().sr2().read(); !sr2.msl() && !sr2.busy() @@ -170,7 +202,7 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> { // Wait until address was sent // Wait for the address to be acknowledged // Check for any I2C errors. If a NACK occurs, the ADDR bit will never be set. - while !self.check_and_clear_error_flags()?.addr() { + while !Self::check_and_clear_error_flags()?.addr() { check_timeout()?; } @@ -190,7 +222,7 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> { // Wait until we're ready for sending while { // Check for any I2C errors. If a NACK occurs, the ADDR bit will never be set. - !self.check_and_clear_error_flags()?.txe() + !Self::check_and_clear_error_flags()?.txe() } { check_timeout()?; } @@ -201,7 +233,7 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> { // Wait until byte is transferred while { // Check for any potential error conditions. - !self.check_and_clear_error_flags()?.btf() + !Self::check_and_clear_error_flags()?.btf() } { check_timeout()?; } @@ -212,7 +244,7 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> { fn recv_byte(&self, check_timeout: impl Fn() -> Result<(), Error>) -> Result { while { // Check for any potential error conditions. - self.check_and_clear_error_flags()?; + Self::check_and_clear_error_flags()?; !T::regs().sr1().read().rxne() } { @@ -237,7 +269,7 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> { }); // Wait until START condition was generated - while !self.check_and_clear_error_flags()?.start() { + while !Self::check_and_clear_error_flags()?.start() { check_timeout()?; } @@ -254,7 +286,7 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> { // Wait until address was sent // Wait for the address to be acknowledged - while !self.check_and_clear_error_flags()?.addr() { + while !Self::check_and_clear_error_flags()?.addr() { check_timeout()?; } @@ -332,26 +364,352 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> { // Async - pub async fn write(&mut self, _address: u8, _write: &[u8]) -> Result<(), Error> + #[inline] // pretty sure this should always be inlined + fn enable_interrupts() -> () { + T::regs().cr2().modify(|w| { + w.set_iterren(true); + w.set_itevten(true); + }); + } + + async fn write_with_stop(&mut self, address: u8, write: &[u8], send_stop: bool) -> Result<(), Error> where TXDMA: crate::i2c::TxDma, { - todo!() + let dma_transfer = unsafe { + let regs = T::regs(); + regs.cr2().modify(|w| { + // DMA mode can be enabled for transmission by setting the DMAEN bit in the I2C_CR2 register. + w.set_dmaen(true); + w.set_itbufen(false); + }); + // Set the I2C_DR register address in the DMA_SxPAR register. The data will be moved to this address from the memory after each TxE event. + let dst = regs.dr().as_ptr() as *mut u8; + + let ch = &mut self.tx_dma; + let request = ch.request(); + Transfer::new_write(ch, request, write, dst, Default::default()) + }; + + let on_drop = OnDrop::new(|| { + let regs = T::regs(); + regs.cr2().modify(|w| { + w.set_dmaen(false); + w.set_iterren(false); + w.set_itevten(false); + }) + }); + + Self::enable_interrupts(); + + // Send a START condition + T::regs().cr1().modify(|reg| { + reg.set_start(true); + }); + + let state = T::state(); + + // Wait until START condition was generated + poll_fn(|cx| { + state.waker.register(cx.waker()); + + match Self::check_and_clear_error_flags() { + Err(e) => Poll::Ready(Err(e)), + Ok(sr1) => { + if sr1.start() { + Poll::Ready(Ok(())) + } else { + Poll::Pending + } + } + } + }) + .await?; + + // Also wait until signalled we're master and everything is waiting for us + Self::enable_interrupts(); + poll_fn(|cx| { + state.waker.register(cx.waker()); + + match Self::check_and_clear_error_flags() { + Err(e) => Poll::Ready(Err(e)), + Ok(_) => { + let sr2 = T::regs().sr2().read(); + if !sr2.msl() && !sr2.busy() { + Poll::Pending + } else { + Poll::Ready(Ok(())) + } + } + } + }) + .await?; + + // Set up current address, we're trying to talk to + Self::enable_interrupts(); + T::regs().dr().write(|reg| reg.set_dr(address << 1)); + + poll_fn(|cx| { + state.waker.register(cx.waker()); + match Self::check_and_clear_error_flags() { + Err(e) => Poll::Ready(Err(e)), + Ok(sr1) => { + if sr1.addr() { + // Clear the ADDR condition by reading SR2. + T::regs().sr2().read(); + Poll::Ready(Ok(())) + } else { + Poll::Pending + } + } + } + }) + .await?; + Self::enable_interrupts(); + let poll_error = poll_fn(|cx| { + state.waker.register(cx.waker()); + + match Self::check_and_clear_error_flags() { + // Unclear why the Err turbofish is necessary here? The compiler didn’t require it in the other + // identical poll_fn check_and_clear matches. + Err(e) => Poll::Ready(Err::(e)), + Ok(_) => Poll::Pending, + } + }); + + // Wait for either the DMA transfer to successfully finish, or an I2C error to occur. + match select(dma_transfer, poll_error).await { + Either::Second(Err(e)) => Err(e), + _ => Ok(()), + }?; + + // The I2C transfer itself will take longer than the DMA transfer, so wait for that to finish too. + + // 18.3.8 “Master transmitter: In the interrupt routine after the EOT interrupt, disable DMA + // requests then wait for a BTF event before programming the Stop condition.” + + // TODO: If this has to be done “in the interrupt routine after the EOT interrupt”, where to put it? + T::regs().cr2().modify(|w| { + w.set_dmaen(false); + }); + + Self::enable_interrupts(); + poll_fn(|cx| { + state.waker.register(cx.waker()); + + match Self::check_and_clear_error_flags() { + Err(e) => Poll::Ready(Err(e)), + Ok(sr1) => { + if sr1.btf() { + if send_stop { + T::regs().cr1().modify(|w| { + w.set_stop(true); + }); + } + + Poll::Ready(Ok(())) + } else { + Poll::Pending + } + } + } + }) + .await?; + + drop(on_drop); + + // Fallthrough is success + Ok(()) } - pub async fn read(&mut self, _address: u8, _buffer: &mut [u8]) -> Result<(), Error> + pub async fn write(&mut self, address: u8, write: &[u8]) -> Result<(), Error> + where + TXDMA: crate::i2c::TxDma, + { + self.write_with_stop(address, write, true).await?; + + // Wait for STOP condition to transmit. + Self::enable_interrupts(); + poll_fn(|cx| { + T::state().waker.register(cx.waker()); + // TODO: error interrupts are enabled here, should we additional check for and return errors? + if T::regs().cr1().read().stop() { + Poll::Pending + } else { + Poll::Ready(Ok(())) + } + }) + .await?; + + Ok(()) + } + + pub async fn read(&mut self, address: u8, buffer: &mut [u8]) -> Result<(), Error> where RXDMA: crate::i2c::RxDma, { - todo!() + let state = T::state(); + let buffer_len = buffer.len(); + + let dma_transfer = unsafe { + let regs = T::regs(); + regs.cr2().modify(|w| { + // DMA mode can be enabled for transmission by setting the DMAEN bit in the I2C_CR2 register. + w.set_itbufen(false); + w.set_dmaen(true); + }); + // Set the I2C_DR register address in the DMA_SxPAR register. The data will be moved to this address from the memory after each TxE event. + let src = regs.dr().as_ptr() as *mut u8; + + let ch = &mut self.rx_dma; + let request = ch.request(); + Transfer::new_read(ch, request, src, buffer, Default::default()) + }; + + let on_drop = OnDrop::new(|| { + let regs = T::regs(); + regs.cr2().modify(|w| { + w.set_dmaen(false); + w.set_iterren(false); + w.set_itevten(false); + }) + }); + + Self::enable_interrupts(); + + // Send a START condition and set ACK bit + T::regs().cr1().modify(|reg| { + reg.set_start(true); + reg.set_ack(true); + }); + + // Wait until START condition was generated + poll_fn(|cx| { + state.waker.register(cx.waker()); + + match Self::check_and_clear_error_flags() { + Err(e) => Poll::Ready(Err(e)), + Ok(sr1) => { + if sr1.start() { + Poll::Ready(Ok(())) + } else { + Poll::Pending + } + } + } + }) + .await?; + + // Also wait until signalled we're master and everything is waiting for us + Self::enable_interrupts(); + poll_fn(|cx| { + state.waker.register(cx.waker()); + + // blocking read didn’t have a check_and_clear call here, but blocking write did so + // I’m adding it here in case that was an oversight. + match Self::check_and_clear_error_flags() { + Err(e) => Poll::Ready(Err(e)), + Ok(_) => { + let sr2 = T::regs().sr2().read(); + if !sr2.msl() && !sr2.busy() { + Poll::Pending + } else { + Poll::Ready(Ok(())) + } + } + } + }) + .await?; + + // Set up current address, we're trying to talk to + T::regs().dr().write(|reg| reg.set_dr((address << 1) + 1)); + + // Wait for the address to be acknowledged + + Self::enable_interrupts(); + poll_fn(|cx| { + state.waker.register(cx.waker()); + + match Self::check_and_clear_error_flags() { + Err(e) => Poll::Ready(Err(e)), + Ok(sr1) => { + if sr1.addr() { + // 18.3.8: When a single byte must be received: the NACK must be programmed during EV6 + // event, i.e. program ACK=0 when ADDR=1, before clearing ADDR flag. + if buffer_len == 1 { + T::regs().cr1().modify(|w| { + w.set_ack(false); + }); + } + Poll::Ready(Ok(())) + } else { + Poll::Pending + } + } + } + }) + .await?; + + // Clear ADDR condition by reading SR2 + T::regs().sr2().read(); + + // 18.3.8: When a single byte must be received: [snip] Then the + // user can program the STOP condition either after clearing ADDR flag, or in the + // DMA Transfer Complete interrupt routine. + if buffer_len == 1 { + T::regs().cr1().modify(|w| { + w.set_stop(true); + }); + } else { + // If, in the I2C_CR2 register, the LAST bit is set, I2C + // automatically sends a NACK after the next byte following EOT_1. The user can + // generate a Stop condition in the DMA Transfer Complete interrupt routine if enabled. + T::regs().cr2().modify(|w| { + w.set_last(true); + }) + } + + // Wait for bytes to be received, or an error to occur. + Self::enable_interrupts(); + let poll_error = poll_fn(|cx| { + state.waker.register(cx.waker()); + + match Self::check_and_clear_error_flags() { + Err(e) => Poll::Ready(Err::(e)), + _ => Poll::Pending, + } + }); + + match select(dma_transfer, poll_error).await { + Either::Second(Err(e)) => Err(e), + _ => Ok(()), + }?; + + // Wait for the STOP to be sent (STOP bit cleared). + Self::enable_interrupts(); + poll_fn(|cx| { + state.waker.register(cx.waker()); + // TODO: error interrupts are enabled here, should we additional check for and return errors? + if T::regs().cr1().read().stop() { + Poll::Pending + } else { + Poll::Ready(Ok(())) + } + }) + .await?; + drop(on_drop); + + // Fallthrough is success + Ok(()) } - pub async fn write_read(&mut self, _address: u8, _write: &[u8], _read: &mut [u8]) -> Result<(), Error> + pub async fn write_read(&mut self, address: u8, write: &[u8], read: &mut [u8]) -> Result<(), Error> where RXDMA: crate::i2c::RxDma, TXDMA: crate::i2c::TxDma, { - todo!() + self.write_with_stop(address, write, false).await?; + self.read(address, read).await } } diff --git a/examples/stm32f4/src/bin/i2c_async.rs b/examples/stm32f4/src/bin/i2c_async.rs new file mode 100644 index 00000000..9f59e4d4 --- /dev/null +++ b/examples/stm32f4/src/bin/i2c_async.rs @@ -0,0 +1,62 @@ +#![no_std] +#![no_main] +#![feature(type_alias_impl_trait)] + +// Example originally designed for stm32f411ceu6 reading an A1454 hall effect sensor on I2C1 +// DMA peripherals changed to compile for stm32f429zi, for the CI. + +use defmt::*; +use embassy_executor::Spawner; +use embassy_stm32::i2c::I2c; +use embassy_stm32::time::Hertz; +use embassy_stm32::{bind_interrupts, i2c, peripherals}; +use {defmt_rtt as _, panic_probe as _}; + +const ADDRESS: u8 = 96; + +bind_interrupts!(struct Irqs { + I2C1_EV => i2c::EventInterruptHandler; + I2C1_ER => i2c::ErrorInterruptHandler; +}); + +#[embassy_executor::main] +async fn main(_spawner: Spawner) { + info!("Hello world!"); + let p = embassy_stm32::init(Default::default()); + + let mut i2c = I2c::new( + p.I2C1, + p.PB8, + p.PB7, + Irqs, + p.DMA1_CH6, + p.DMA1_CH0, + Hertz(100_000), + Default::default(), + ); + + loop { + let a1454_read_sensor_command = [0x1F]; + let mut sensor_data_buffer: [u8; 4] = [0, 0, 0, 0]; + + match i2c + .write_read(ADDRESS, &a1454_read_sensor_command, &mut sensor_data_buffer) + .await + { + Ok(()) => { + // Convert 12-bit signed integer into 16-bit signed integer. + // Is the 12 bit number negative? + if (sensor_data_buffer[2] & 0b00001000) == 0b0001000 { + sensor_data_buffer[2] = sensor_data_buffer[2] | 0b11110000; + } + + let mut sensor_value_raw: u16 = sensor_data_buffer[3].into(); + sensor_value_raw |= (sensor_data_buffer[2] as u16) << 8; + let sensor_value: u16 = sensor_value_raw.into(); + let sensor_value = sensor_value as i16; + info!("Data: {}", sensor_value); + } + Err(e) => error!("I2C Error during read: {:?}", e), + } + } +} diff --git a/examples/stm32f4/src/bin/i2c_comparison.rs b/examples/stm32f4/src/bin/i2c_comparison.rs new file mode 100644 index 00000000..6d23c0ed --- /dev/null +++ b/examples/stm32f4/src/bin/i2c_comparison.rs @@ -0,0 +1,135 @@ +#![no_std] +#![no_main] +#![feature(type_alias_impl_trait)] + +// Example originally designed for stm32f411ceu6 with three A1454 hall effect sensors, connected to I2C1, 2 and 3 +// on the pins referenced in the peripheral definitions. +// Pins and DMA peripherals changed to compile for stm32f429zi, to work with the CI. +// MUST be compiled in release mode to see actual performance, otherwise the async transactions take 2x +// as long to complete as the blocking ones! + +use defmt::*; +use embassy_executor::Spawner; +use embassy_stm32::i2c::I2c; +use embassy_stm32::time::Hertz; +use embassy_stm32::{bind_interrupts, i2c, peripherals}; +use embassy_time::Instant; +use futures::future::try_join3; +use {defmt_rtt as _, panic_probe as _}; + +const ADDRESS: u8 = 96; + +bind_interrupts!(struct Irqs { + I2C1_EV => i2c::EventInterruptHandler; + I2C1_ER => i2c::ErrorInterruptHandler; + I2C2_EV => i2c::EventInterruptHandler; + I2C2_ER => i2c::ErrorInterruptHandler; + I2C3_EV => i2c::EventInterruptHandler; + I2C3_ER => i2c::ErrorInterruptHandler; +}); + +/// Convert 12-bit signed integer within a 4 byte long buffer into 16-bit signed integer. +fn a1454_buf_to_i16(buffer: &[u8; 4]) -> i16 { + let lower = buffer[3]; + let mut upper = buffer[2]; + // Fill in additional 1s if the 12 bit number is negative. + if (upper & 0b00001000) == 0b0001000 { + upper = upper | 0b11110000; + } + + let mut sensor_value_raw: u16 = lower.into(); + sensor_value_raw |= (upper as u16) << 8; + let sensor_value: u16 = sensor_value_raw.into(); + let sensor_value = sensor_value as i16; + sensor_value +} + +#[embassy_executor::main] +async fn main(_spawner: Spawner) { + info!("Setting up peripherals."); + let p = embassy_stm32::init(Default::default()); + + let mut i2c1 = I2c::new( + p.I2C1, + p.PB8, + p.PB7, + Irqs, + p.DMA1_CH6, + p.DMA1_CH0, + Hertz(100_000), + Default::default(), + ); + + let mut i2c2 = I2c::new( + p.I2C2, + p.PB10, + p.PB11, + Irqs, + p.DMA1_CH7, + p.DMA1_CH3, + Hertz(100_000), + Default::default(), + ); + + let mut i2c3 = I2c::new( + p.I2C3, + p.PA8, + p.PC9, + Irqs, + p.DMA1_CH4, + p.DMA1_CH2, + Hertz(100_000), + Default::default(), + ); + + let a1454_read_sensor_command = [0x1F]; + let mut i2c1_buffer: [u8; 4] = [0, 0, 0, 0]; + let mut i2c2_buffer: [u8; 4] = [0, 0, 0, 0]; + let mut i2c3_buffer: [u8; 4] = [0, 0, 0, 0]; + loop { + // Blocking reads one after the other. Completes in about 2000us. + let blocking_read_start_us = Instant::now().as_micros(); + match i2c1.blocking_write_read(ADDRESS, &a1454_read_sensor_command, &mut i2c1_buffer) { + Ok(()) => {} + Err(e) => error!("I2C Error: {:?}", e), + } + match i2c2.blocking_write_read(ADDRESS, &a1454_read_sensor_command, &mut i2c2_buffer) { + Ok(()) => {} + Err(e) => error!("I2C Error: {:?}", e), + } + match i2c3.blocking_write_read(ADDRESS, &a1454_read_sensor_command, &mut i2c3_buffer) { + Ok(()) => {} + Err(e) => error!("I2C Error: {:?}", e), + } + let blocking_read_total_us = Instant::now().as_micros() - blocking_read_start_us; + info!( + "Blocking reads completed in {}us: i2c1: {} i2c2: {} i2c3: {}", + blocking_read_total_us, + a1454_buf_to_i16(&i2c1_buffer), + a1454_buf_to_i16(&i2c2_buffer), + a1454_buf_to_i16(&i2c3_buffer) + ); + + // Async reads overlapping. Completes in about 1000us. + let async_read_start_us = Instant::now().as_micros(); + + let i2c1_result = i2c1.write_read(ADDRESS, &a1454_read_sensor_command, &mut i2c1_buffer); + let i2c2_result = i2c2.write_read(ADDRESS, &a1454_read_sensor_command, &mut i2c2_buffer); + let i2c3_result = i2c3.write_read(ADDRESS, &a1454_read_sensor_command, &mut i2c3_buffer); + + // Wait for all three transactions to finish, or any one of them to fail. + match try_join3(i2c1_result, i2c2_result, i2c3_result).await { + Ok(_) => { + let async_read_total_us = Instant::now().as_micros() - async_read_start_us; + info!( + "Async reads completed in {}us: i2c1: {} i2c2: {} i2c3: {}", + async_read_total_us, + a1454_buf_to_i16(&i2c1_buffer), + a1454_buf_to_i16(&i2c2_buffer), + a1454_buf_to_i16(&i2c3_buffer) + ); + } + Err(e) => error!("I2C Error during async write-read: {}", e), + }; + } +}