From 2dfb08562d3314c9c8b1a502a1d360bcdfd2bb20 Mon Sep 17 00:00:00 2001
From: Akshat Saxena <akshat2112@gmail.com>
Date: Tue, 25 Feb 2025 16:40:03 -0800
Subject: [PATCH] Add i2c 10-bit loopback async example

---
 .../src/bin/i2c-loopback-async-10bit.rs       | 145 ++++++++++++++++++
 1 file changed, 145 insertions(+)
 create mode 100644 examples/rt685s-evk/src/bin/i2c-loopback-async-10bit.rs

diff --git a/examples/rt685s-evk/src/bin/i2c-loopback-async-10bit.rs b/examples/rt685s-evk/src/bin/i2c-loopback-async-10bit.rs
new file mode 100644
index 00000000..7d495312
--- /dev/null
+++ b/examples/rt685s-evk/src/bin/i2c-loopback-async-10bit.rs
@@ -0,0 +1,145 @@
+#![no_std]
+#![no_main]
+
+extern crate embassy_imxrt_examples;
+
+use defmt::info;
+use embassy_executor::Spawner;
+use embassy_imxrt::i2c::master::{I2cMaster, Speed};
+use embassy_imxrt::i2c::slave::{Address, Command, I2cSlave, Response};
+use embassy_imxrt::i2c::{self, Async};
+use embassy_imxrt::{bind_interrupts, peripherals};
+use embedded_hal_async::i2c::I2c;
+
+const ADDR: u16 = 0x0123;
+const MASTER_BUFLEN: usize = 8;
+// slave buffer has to be 1 bigger than master buffer because master does not
+// handle end of read properly
+const SLAVE_BUFLEN: usize = MASTER_BUFLEN + 1;
+const SLAVE_ADDR: Option<Address> = Address::new_10bit(ADDR);
+
+bind_interrupts!(struct Irqs {
+    FLEXCOMM2 => i2c::InterruptHandler<peripherals::FLEXCOMM2>;
+    FLEXCOMM4 => i2c::InterruptHandler<peripherals::FLEXCOMM4>;
+});
+
+/// Generate a buffer with increment numbers
+fn generate_buffer<const SIZE: usize>() -> [u8; SIZE] {
+    let mut buf = [0xAA; SIZE];
+    for (i, e) in buf.iter_mut().enumerate() {
+        *e = i as u8;
+    }
+    buf
+}
+
+#[embassy_executor::task]
+async fn slave_service(mut slave: I2cSlave<'static, Async>) {
+    loop {
+        // Buffer containing data read by the master
+        let t_buf: [u8; SLAVE_BUFLEN] = generate_buffer();
+
+        // Buffer that the master writes to
+        let mut r_buf = [0xAA; SLAVE_BUFLEN];
+        // Buffer to compare with written data
+        let expected_buf: [u8; SLAVE_BUFLEN] = generate_buffer();
+
+        match slave.listen().await.unwrap() {
+            Command::Probe => {
+                info!("Probe, nothing to do");
+            }
+            Command::Read => {
+                info!("Read");
+                loop {
+                    match slave.respond_to_read(&t_buf).await.unwrap() {
+                        Response::Complete(n) => {
+                            info!("Response complete read with {} bytes", n);
+                            break;
+                        }
+                        Response::Pending(n) => info!("Response to read got {} bytes, more bytes to fill", n),
+                    }
+                }
+            }
+            Command::Write => {
+                info!("Write");
+                loop {
+                    match slave.respond_to_write(&mut r_buf).await.unwrap() {
+                        Response::Complete(n) => {
+                            info!("Response complete write with {} bytes", n);
+                            info!("i2cm write data: {:x}", r_buf[0..n]);
+
+                            // Compare written data with expected data
+                            // Ensures that the second byte of 10 bit address is handled properly
+                            assert!(r_buf[0..n] == expected_buf[0..n]);
+                            break;
+                        }
+                        Response::Pending(n) => info!("Response to write got {} bytes, more bytes pending", n),
+                    }
+                }
+            }
+        }
+    }
+}
+
+#[embassy_executor::task]
+async fn master_service(mut master: I2cMaster<'static, Async>) {
+    const ADDR: u16 = 0x0123;
+
+    // Buffer containing data to write to slave
+    let w_buf: [u8; MASTER_BUFLEN] = generate_buffer();
+
+    // Buffer to compare with read data
+    let expected_buf: [u8; SLAVE_BUFLEN] = generate_buffer();
+
+    let mut i: usize = 0;
+    loop {
+        // Reset read buffer to ensure fresh data
+        let mut r_buf = [0xAA; MASTER_BUFLEN];
+
+        if i < 10 {
+            let w_end = i % w_buf.len();
+            info!("i2cm write {} bytes", w_end);
+            master.write(ADDR, &w_buf[0..w_end]).await.unwrap();
+        } else if i < 20 {
+            let r_end = i % (r_buf.len() - 1) + 2;
+            info!("i2cm read {} bytes", r_end);
+            master.read(ADDR, &mut r_buf[0..r_end]).await.unwrap();
+            info!("i2cm read data: {:x}", r_buf[0..r_end]);
+
+            // Compare read data with expected data
+            // Ensures that the second byte of 10 bit address is handled properly
+            assert!(r_buf[0..r_end] == expected_buf[0..r_end]);
+        } else {
+            let tend = i % w_buf.len() + 1;
+            let r_end = i % (r_buf.len() - 1) + 2;
+            info!("i2cm write {} bytes, read {} bytes", tend, r_end);
+            master
+                .write_read(ADDR, &w_buf[0..tend], &mut r_buf[0..r_end])
+                .await
+                .unwrap();
+            info!("i2cm read data: {:x}", r_buf[0..r_end]);
+
+            // Compare read data with expected data
+            // Ensures that the second byte of 10 bit address is handled properly
+            assert!(r_buf[0..r_end] == expected_buf[0..r_end]);
+        }
+        i += 1;
+
+        if i == 30 {
+            info!("i2c 10 bit loopback test end");
+            break;
+        }
+    }
+}
+
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    info!("i2c loopback example");
+    let p = embassy_imxrt::init(Default::default());
+
+    let slave = I2cSlave::new_async(p.FLEXCOMM2, p.PIO0_18, p.PIO0_17, Irqs, SLAVE_ADDR.unwrap(), p.DMA0_CH4).unwrap();
+
+    let master = I2cMaster::new_async(p.FLEXCOMM4, p.PIO0_29, p.PIO0_30, Irqs, Speed::Standard, p.DMA0_CH9).unwrap();
+
+    spawner.must_spawn(master_service(master));
+    spawner.must_spawn(slave_service(slave));
+}