From 6522374ce0bd8fb300db3b21195c4306c4d264a4 Mon Sep 17 00:00:00 2001
From: Benjamin Koch <bbbsnowball@gmail.com>
Date: Sat, 13 May 2023 06:36:15 +0200
Subject: [PATCH] give up: do I2C scan with bitbanging - like everyone else
seems to do
---
firmware/rust1/src/bin/heizung.rs | 119 +++++++++++++++++++++++++++---
1 file changed, 107 insertions(+), 12 deletions(-)
diff --git a/firmware/rust1/src/bin/heizung.rs b/firmware/rust1/src/bin/heizung.rs
index 42947b7..0203324 100644
--- a/firmware/rust1/src/bin/heizung.rs
+++ b/firmware/rust1/src/bin/heizung.rs
@@ -4,11 +4,12 @@
use defmt::*;
use embassy_executor::Spawner;
+use embassy_futures::select::select;
+use embassy_futures::select::Either::*;
use embassy_rp::gpio;
use embassy_time::{Duration, Timer};
-use embassy_rp::gpio::{Input, Level, Output, Pull};
-//use embassy_rp::i2c;
-use heizung::rp::i2c;
+use embassy_rp::gpio::{Input, Level, Output, Pull, Flex};
+use embassy_rp::i2c;
use embassy_rp::interrupt;
use embedded_hal_async::i2c::I2c;
use embassy_rp::peripherals::{UART0, I2C0};
@@ -71,21 +72,116 @@ fn format_scan_result<const N : usize>(msg : &mut String<N>, scan_result : [Scan
Ok(())
}
+async fn _clockStretch<'d, SCL: gpio::Pin>(scl: &mut Flex<'d, SCL>) -> Result<(), i2c::Error> {
+ use i2c::Error::*;
+ use i2c::AbortReason::*;
+
+ if scl.is_high() {
+ return Ok(())
+ }
+
+ let is_high = scl.wait_for_high();
+ let timeout = Timer::after(Duration::from_micros(100));
+
+ return match select(is_high, timeout).await {
+ First(_) => Ok(()),
+ Second(_) => Err(Abort(ArbitrationLoss)),
+ }
+}
+
+// adapted from https://github.com/earlephilhower/arduino-pico/blob/6e52b72523b11470b2ad2b0578ca1500be238108/libraries/Wire/src/Wire.cpp#L257
+async fn i2c_write_zero_bytes_middle_part<'d, SCL: gpio::Pin, SDA: gpio::Pin, const FREQ : u64>(
+ mut addr: u16, delay: Duration, scl: &mut Flex<'d, SCL>, sda: &mut Flex<'d, SDA>)
+ -> Result<(), i2c::Error> {
+ sda.set_as_input();
+ Timer::after(delay).await;
+ scl.set_as_input();
+ _clockStretch(scl).await?;
+ sda.set_as_output();
+ Timer::after(delay).await;
+ scl.set_as_output();
+ Timer::after(delay).await;
+ for i in 0..8 {
+ addr <<= 1;
+ sda.set_level(if (addr & (1 << 7)) != 0 { gpio::Level::High } else { gpio::Level::Low });
+ Timer::after(delay).await;
+ scl.set_as_input();
+ Timer::after(delay).await;
+ _clockStretch(scl).await?;
+ scl.set_as_output();
+ Timer::after(Duration::from_micros(5)).await; // Ensure we don't change too close to clock edge
+ }
+
+ sda.set_as_input();
+ Timer::after(delay).await;
+ scl.set_as_input();
+ _clockStretch(scl).await?;
+
+ let result = if sda.is_low() {
+ Ok(())
+ } else {
+ use i2c::Error::*;
+ use i2c::AbortReason::*;
+ Err(Abort(NoAcknowledge))
+ };
+ Timer::after(delay).await;
+ scl.set_as_output();
+
+ result
+}
+async fn i2c_write_zero_bytes<SCL: gpio::Pin, SDA: gpio::Pin, const FREQ : u64>(mut addr: u16, scl: &mut SCL, sda: &mut SDA)
+ -> Result<(), i2c::Error> {
+ use i2c::Error::*;
+ use i2c::AbortReason::*;
+
+ let delay = Duration::from_micros((1000000 / FREQ) / 2);
+ let ack = false;
+
+ let mut sda = Flex::new(sda);
+ let mut scl = Flex::new(scl);
+ sda.set_as_input();
+ sda.set_pull(Pull::Up);
+ scl.set_as_input();
+ scl.set_pull(Pull::Up);
+ // We only need low or pullup so we can set the value to low and only toggle direction.
+ // This is how OutputOpenDrain does it (and the only reason we use Flex is because we want the pullup).
+ sda.set_low();
+ scl.set_low();
+
+ Timer::after(delay).await;
+ if sda.is_low() || scl.is_low() {
+ return Err(Abort(ArbitrationLoss))
+ }
+
+ let result = i2c_write_zero_bytes_middle_part::<_, _, FREQ>(addr, delay, &mut scl, &mut sda).await;
+
+ Timer::after(delay).await;
+ sda.set_as_output();
+ Timer::after(delay).await;
+ scl.set_as_input();
+ Timer::after(delay).await;
+ sda.set_as_input();
+ Timer::after(delay).await;
+
+ return result;
+}
+
#[embassy_executor::task]
-async fn i2c_task(mut i2c: i2c::I2c<'static, I2C0, i2c::Async>) {
+async fn i2c_task(mut i2c_peri: embassy_rp::peripherals::I2C0,
+ mut scl: embassy_rp::peripherals::PIN_13, mut sda: embassy_rp::peripherals::PIN_12,
+ mut i2c_irq: embassy_rp::interrupt::I2C0_IRQ, i2c_config: i2c::Config) {
use i2c::Error::*;
use i2c::AbortReason::*;
loop {
+ if true {
+ let mut i2c = i2c::I2c::new_async(&mut i2c_peri, &mut scl, &mut sda, &mut i2c_irq, i2c_config);
+ }
+
const MAX_ADDRESS : u8 = 128;
let mut scan_result = [ScanResult::Error; MAX_ADDRESS as usize];
for i in 0..MAX_ADDRESS {
- //NOTE It looks like the blocking implementation doesn't accept an empty buffer
- // but the async one does. Lucky for us because we need that here!
- // -> Actually, it doesn't. It just hangs.
- info!("I2C testing: {}", i);
- //FIXME Don't test with buffer size 1 because that will actually write, which can cause all kinds of issues!
- match i2c.write_async(i.into(), [0; 0]).await {
+ match i2c_write_zero_bytes::<_, _, 400_000>(i as u16, &mut scl, &mut sda).await {
Result::Ok(()) => {
//info!("I2C ok: {}", i);
scan_result[i as usize] = ScanResult::Ack
@@ -155,8 +251,7 @@ async fn main(spawner: Spawner) {
let i2c_irq = interrupt::take!(I2C0_IRQ);
let mut i2c_config = i2c::Config::default();
i2c_config.frequency = 400_000;
- let i2c = i2c::I2c::new_async(p.I2C0, scl, sda, i2c_irq, i2c_config);
- unwrap!(spawner.spawn(i2c_task(i2c)));
+ unwrap!(spawner.spawn(i2c_task(p.I2C0, scl, sda, i2c_irq, i2c_config)));
// use 19200 baud in 8E1 mode - not great but Modbus default
let mut uart_config = uart::Config::default();
--
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