Merge #1119

1119: add convert_to_celsius function in the adc module r=lulf a=overheat

    modify RP2040 adc example to get inside biased bipolar diode voltage,
    then convert this temperature sensor data into Celsius degree,
    according to chapter 4.9.5. Temperature Sensor in RP2040 datasheet.

Co-authored-by: Aaron Tsui <[email protected]>

1 files changed, 6 insertions, 1 deletions

diff --git a/examples/rp/src/bin/adc.rs b/examples/rp/src/bin/adc.rs
index 2a9e93732..4202fd394 100644
--- a/examples/rp/src/bin/adc.rs
+++ b/examples/rp/src/bin/adc.rs
@@ -27,7 +27,12 @@ async fn main(_spawner: Spawner) {
         let level = adc.read(&mut p28).await;
         info!("Pin 28 ADC: {}", level);
         let temp = adc.read_temperature().await;
-        info!("Temp: {}", temp);
+        info!("Temp: {} degrees", convert_to_celsius(temp));
         Timer::after(Duration::from_secs(1)).await;
     }
 }
+
+fn convert_to_celsius(raw_temp: u16) -> f32 {
+    // According to chapter 4.9.5. Temperature Sensor in RP2040 datasheet
+    27.0 - (raw_temp as f32 * 3.3 / 4096.0 - 0.706) / 0.001721 as f32
+}