Add example, fix small bug in respond_and_fill

embassy-rp/src/i2c_slave.rs

@@ -287,6 +287,18 @@ impl<'d, T: Instance> I2cSlave<'d, T> {
         }
     }
 
+    /// Respond to a master read, then fill any remaining read bytes with `fill`
+    pub async fn respond_and_fill(&mut self, buffer: &[u8], fill: u8) -> Result<ReadStatus, Error> {
+        let resp_stat = self.respond_to_read(buffer).await?;
+
+        if resp_stat == ReadStatus::NeedMoreBytes {
+            self.respond_till_stop(fill).await?;
+            Ok(ReadStatus::Done)
+        } else {
+            Ok(resp_stat)
+        }
+    }
+
     #[inline(always)]
     fn read_and_clear_abort_reason(&mut self) -> Result<(), Error> {
         let p = T::regs();

examples/rp/src/bin/i2c_slave.rs

@@ -0,0 +1,118 @@
+//! This example shows how to use the 2040 as an i2c slave.
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_rp::peripherals::{I2C0, I2C1};
+use embassy_rp::{bind_interrupts, i2c, i2c_slave};
+use embassy_time::{Duration, Timer};
+use embedded_hal_async::i2c::I2c;
+use {defmt_rtt as _, panic_probe as _};
+
+bind_interrupts!(struct Irqs {
+    I2C0_IRQ => i2c::InterruptHandler<I2C0>;
+    I2C1_IRQ => i2c::InterruptHandler<I2C1>;
+});
+
+const DEV_ADDR: u8 = 0x42;
+
+#[embassy_executor::task]
+async fn device_task(mut dev: i2c_slave::I2cSlave<'static, I2C1>) -> ! {
+    info!("Device start");
+
+    let mut state = 0;
+
+    loop {
+        let mut buf = [0u8; 128];
+        match dev.listen(&mut buf).await {
+            Ok(i2c_slave::Command::GeneralCall(len)) => info!("Device recieved general call write: {}", buf[..len]),
+            Ok(i2c_slave::Command::Read) => loop {
+                match dev.respond_to_read(&[state]).await {
+                    Ok(x) => match x {
+                        i2c_slave::ReadStatus::Done => break,
+                        i2c_slave::ReadStatus::NeedMoreBytes => (),
+                        i2c_slave::ReadStatus::LeftoverBytes(x) => {
+                            info!("tried to write {} extra bytes", x);
+                            break;
+                        }
+                    },
+                    Err(e) => error!("error while responding {}", e),
+                }
+            },
+            Ok(i2c_slave::Command::Write(len)) => info!("Device recieved write: {}", buf[..len]),
+            Ok(i2c_slave::Command::WriteRead(len)) => {
+                info!("device recieved write read: {:x}", buf[..len]);
+                match buf[0] {
+                    // Set the state
+                    0xC2 => {
+                        state = buf[1];
+                        match dev.respond_and_fill(&[state], 0x00).await {
+                            Ok(read_status) => info!("response read status {}", read_status),
+                            Err(e) => error!("error while responding {}", e),
+                        }
+                    }
+                    // Reset State
+                    0xC8 => {
+                        state = 0;
+                        match dev.respond_and_fill(&[state], 0x00).await {
+                            Ok(read_status) => info!("response read status {}", read_status),
+                            Err(e) => error!("error while responding {}", e),
+                        }
+                    }
+                    x => error!("Invalid Write Read {:x}", x),
+                }
+            }
+            Err(e) => error!("{}", e),
+        }
+    }
+}
+
+#[embassy_executor::task]
+async fn controller_task(mut con: i2c::I2c<'static, I2C0, i2c::Async>) {
+    info!("Controller start");
+
+    loop {
+        let mut resp_buff = [0u8; 2];
+        for i in 0..10 {
+            match con.write_read(DEV_ADDR, &[0xC2, i], &mut resp_buff).await {
+                Ok(_) => info!("write_read response: {}", resp_buff),
+                Err(e) => error!("Error writing {}", e),
+            }
+
+            Timer::after(Duration::from_millis(100)).await;
+        }
+        match con.read(DEV_ADDR, &mut resp_buff).await {
+            Ok(_) => info!("read response: {}", resp_buff),
+            Err(e) => error!("Error writing {}", e),
+        }
+        match con.write_read(DEV_ADDR, &[0xC8], &mut resp_buff).await {
+            Ok(_) => info!("write_read response: {}", resp_buff),
+            Err(e) => error!("Error writing {}", e),
+        }
+        Timer::after(Duration::from_millis(100)).await;
+    }
+}
+
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+    info!("Hello World!");
+
+    let d_sda = p.PIN_3;
+    let d_scl = p.PIN_2;
+    let mut config = i2c_slave::Config::default();
+    config.addr = DEV_ADDR as u16;
+    let device = i2c_slave::I2cSlave::new(p.I2C1, d_sda, d_scl, Irqs, config);
+
+    unwrap!(spawner.spawn(device_task(device)));
+
+    let c_sda = p.PIN_1;
+    let c_scl = p.PIN_0;
+    let mut config = i2c::Config::default();
+    config.frequency = 5_000;
+    let controller = i2c::I2c::new_async(p.I2C0, c_sda, c_scl, Irqs, config);
+
+    unwrap!(spawner.spawn(controller_task(controller)));
+}