stm32/i2c: implement async i2c v1.

2 files changed, 197 insertions, 0 deletions

diff --git a/examples/stm32f4/src/bin/i2c_async.rs b/examples/stm32f4/src/bin/i2c_async.rs
new file mode 100644
index 000000000..9f59e4d41
--- /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<peripherals::I2C1>;
+    I2C1_ER => i2c::ErrorInterruptHandler<peripherals::I2C1>;
+});
+
+#[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 000000000..6d23c0ed8
--- /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<peripherals::I2C1>;
+    I2C1_ER => i2c::ErrorInterruptHandler<peripherals::I2C1>;
+    I2C2_EV => i2c::EventInterruptHandler<peripherals::I2C2>;
+    I2C2_ER => i2c::ErrorInterruptHandler<peripherals::I2C2>;
+    I2C3_EV => i2c::EventInterruptHandler<peripherals::I2C3>;
+    I2C3_ER => i2c::ErrorInterruptHandler<peripherals::I2C3>;
+});
+
+/// 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),
+        };
+    }
+}