Updated the pio onewire example

examples/rp/src/bin/pio_onewire.rs

@@ -1,4 +1,4 @@
-//! This example shows how you can use PIO to read a `DS18B20` one-wire temperature sensor.
+//! This example shows how you can use PIO to read one or more `DS18B20` one-wire temperature sensors.
 
 #![no_std]
 #![no_main]
@@ -6,9 +6,10 @@ use defmt::*;
 use embassy_executor::Spawner;
 use embassy_rp::bind_interrupts;
 use embassy_rp::peripherals::PIO0;
-use embassy_rp::pio::{self, InterruptHandler, Pio};
+use embassy_rp::pio::{InterruptHandler, Pio};
-use embassy_rp::pio_programs::onewire::{PioOneWire, PioOneWireProgram};
+use embassy_rp::pio_programs::onewire::{PioOneWire, PioOneWireProgram, PioOneWireSearch};
 use embassy_time::Timer;
+use heapless::Vec;
 use {defmt_rtt as _, panic_probe as _};
 
 bind_interrupts!(struct Irqs {
@@ -21,63 +22,66 @@ async fn main(_spawner: Spawner) {
     let mut pio = Pio::new(p.PIO0, Irqs);
 
     let prg = PioOneWireProgram::new(&mut pio.common);
-    let onewire = PioOneWire::new(&mut pio.common, pio.sm0, p.PIN_2, &prg);
+    let mut onewire = PioOneWire::new(&mut pio.common, pio.sm0, p.PIN_2, &prg);
 
-    let mut sensor = Ds18b20::new(onewire);
+    info!("Starting onewire search");
+
+    let mut devices = Vec::<u64, 10>::new();
+    let mut search = PioOneWireSearch::new();
+    for _ in 0..10 {
+        if !search.is_finished() {
+            if let Some(address) = search.next(&mut onewire).await {
+                if crc8(&address.to_le_bytes()) == 0 {
+                    info!("Found addres: {:x}", address);
+                    let _ = devices.push(address);
+                } else {
+                    warn!("Found invalid address: {:x}", address);
+                }
+            }
+        }
+    }
+
+    info!("Search done, found {} devices", devices.len());
 
     loop {
-        sensor.start().await; // Start a new measurement
+        onewire.reset().await;
+        // Skip rom and trigger conversion, we can trigger all devices on the bus immediately
+        onewire.write_bytes(&[0xCC, 0x44]).await;
+
         Timer::after_secs(1).await; // Allow 1s for the measurement to finish
-        match sensor.temperature().await {
+
-            Ok(temp) => info!("temp = {:?} deg C", temp),
+        // Read all devices one by one
-            _ => error!("sensor error"),
+        for device in &devices {
+            onewire.reset().await;
+            onewire.write_bytes(&[0x55]).await; // Match rom
+            onewire.write_bytes(&device.to_le_bytes()).await;
+            onewire.write_bytes(&[0xBE]).await; // Read scratchpad
+
+            let mut data = [0; 9];
+            onewire.read_bytes(&mut data).await;
+            if crc8(&data) == 0 {
+                let temp = ((data[1] as u32) << 8 | data[0] as u32) as f32 / 16.;
+                info!("Read device {:x}: {} deg C", device, temp);
+            } else {
+                warn!("Reading device {:x} failed", device);
+            }
         }
         Timer::after_secs(1).await;
     }
 }
 
-/// DS18B20 temperature sensor driver
+fn crc8(data: &[u8]) -> u8 {
-pub struct Ds18b20<'d, PIO: pio::Instance, const SM: usize> {
+    let mut crc = 0;
-    wire: PioOneWire<'d, PIO, SM>,
+    for b in data {
-}
+        let mut data_byte = *b;
-
+        for _ in 0..8 {
-impl<'d, PIO: pio::Instance, const SM: usize> Ds18b20<'d, PIO, SM> {
+            let temp = (crc ^ data_byte) & 0x01;
-    pub fn new(wire: PioOneWire<'d, PIO, SM>) -> Self {
+            crc >>= 1;
-        Self { wire }
+            if temp != 0 {
-    }
+                crc ^= 0x8C;
-
-    /// Calculate CRC8 of the data
-    fn crc8(data: &[u8]) -> u8 {
-        let mut temp;
-        let mut data_byte;
-        let mut crc = 0;
-        for b in data {
-            data_byte = *b;
-            for _ in 0..8 {
-                temp = (crc ^ data_byte) & 0x01;
-                crc >>= 1;
-                if temp != 0 {
-                    crc ^= 0x8C;
-                }
-                data_byte >>= 1;
             }
-        }
+            data_byte >>= 1;
-        crc
-    }
-
-    /// Start a new measurement. Allow at least 1000ms before getting `temperature`.
-    pub async fn start(&mut self) {
-        self.wire.write_bytes(&[0xCC, 0x44]).await;
-    }
-
-    /// Read the temperature. Ensure >1000ms has passed since `start` before calling this.
-    pub async fn temperature(&mut self) -> Result<f32, ()> {
-        self.wire.write_bytes(&[0xCC, 0xBE]).await;
-        let mut data = [0; 9];
-        self.wire.read_bytes(&mut data).await;
-        match Self::crc8(&data) == 0 {
-            true => Ok(((data[1] as u32) << 8 | data[0] as u32) as f32 / 16.),
-            false => Err(()),
         }
     }
+    crc
 }