Cargo.toml

@@ -128,6 +128,7 @@ license.workspace = true
 
 [features]
 thermocouple_k = []
+lm35 = []
 
 [dependencies]
 uom = { workspace = true }

examples/ads1256/Cargo.toml

@@ -9,7 +9,7 @@ license.workspace = true
 
 [dependencies.physical]
 path = "../.."
-features = ["thermocouple_k"]
+features = ["thermocouple_k", "lm35"]
 [dependencies.physical-node]
 path = "../../node"
 features = ["embassy-sync"]

examples/ads1256/src/bin/thermocouple.rs

@@ -10,7 +10,7 @@ use {defmt_rtt as _, panic_probe as _};
 
 use {embassy_executor as executor, embassy_stm32 as stm32};
 
-use ads1256::standard::input::SingleEnded;
+use ads1256::standard::input::{Differential, SingleEnded};
 use ads1256::{
     AdControl, Ads1256, AutoCal, BitOrder, BlockingDelay, Buffer, ClockOut, Config, DState,
     DataRate, DigitalIo, DigitalIoDirection, DigitalIoState, DioDirection, Gain, Multiplexer,
@@ -29,12 +29,12 @@ use uom::si::electric_potential::{millivolt, volt};
 use uom::si::f32;
 
 use defmt::{debug, error, info, trace, unwrap};
-use physical::transducer::thermocouple_k;
+use physical::transducer::{lm35, thermocouple_k};
 use uom::si::thermodynamic_temperature::degree_celsius;
 
 const AUTOCAL_CONF: Config = Config {
     status: Status::setting(Buffer::Enabled, AutoCal::Enabled, BitOrder::MostSigFirst),
-    multiplexer: Multiplexer::setting(MuxInput::AIn0, MuxInput::Common),
+    multiplexer: Multiplexer::setting(MuxInput::AIn0, MuxInput::AIn1),
     ad_control: AdControl::setting(Gain::X64, Sdcs::Off, ClockOut::Off),
     data_rate: DataRate::Sps2_5,
     digital_io: DigitalIo::setting(DigitalIoState::default(), DigitalIoDirection::default()),
@@ -87,24 +87,40 @@ async fn main(spawner: Spawner) {
     ads_1256.write_config(&mut spi, AUTOCAL_CONF).unwrap();
     ads_1256.self_calibrate(&mut spi).await.unwrap();
 
-    let reference_temp = f32::ThermodynamicTemperature::new::<degree_celsius>(26.0);
-
-    // Zero test
-    let zero_voltage = f32::ElectricPotential::new::<millivolt>(0.0);
-    let zero_temperature = thermocouple_k::convert_direct(zero_voltage, reference_temp).unwrap();
-    let zero_celsius = zero_temperature.get::<degree_celsius>();
-    info!("Zero test: {}", zero_celsius);
-
     loop {
-        Delay.delay_ms(1_000u16);
+        let gain = Gain::X2;
+        let reference = ads_1256
+            .autocal_convert(
+                &mut spi,
+                Differential::AIn0.into(),
+                None,
+                Some(AUTOCAL_CONF.ad_control.with_gain(gain)),
+                None,
+                false,
+            )
+            .await
+            .unwrap()
+            .to_voltage(gain);
+        let reference = lm35::convert(reference).unwrap();
+        let reference_celsius = reference.get::<degree_celsius>();
+        info!("Reference junction temperature in degrees celsius: {}", reference_celsius);
+
+        let gain = Gain::X64;
         let voltage = ads_1256
-            .read_data(&mut spi)
+            .autocal_convert(
+                &mut spi,
+                Differential::AIn1.into(),
+                None,
+                Some(AUTOCAL_CONF.ad_control.with_gain(gain)),
+                None,
+                false,
+            )
             .await
             .unwrap()
             .to_voltage(AUTOCAL_CONF.ad_control.gain());
         let mv = voltage.get::<millivolt>();
-        let temperature = thermocouple_k::convert_direct(voltage, reference_temp).unwrap();
+        let temperature = thermocouple_k::convert_direct(voltage, reference).unwrap();
         let celsius = temperature.get::<degree_celsius>();
-        info!("Temperature in degrees celsius: {}, millivolts: {}", celsius, mv);
+        info!("Thermocouple temperature in degrees celsius: {}, millivolts: {}", celsius, mv);
     }
 }

src/transducer/mod.rs

@@ -3,10 +3,9 @@ use crate::cell::CellView;
 
 pub mod input;
 pub mod output;
-mod thermocouple;
+mod part;
 
-#[cfg(feature = "thermocouple_k")]
-pub use thermocouple::type_k as thermocouple_k;
+pub use part::*;
 
 // Initialisation will always be async and won't complete until a state is available for all
 // stateful transducers.

src/transducer/part/lm35.rs

@@ -0,0 +1,22 @@
+use crate::transducer::InvalidValue;
+use uom::si::electric_potential::volt;
+use uom::si::f32;
+use uom::si::thermodynamic_temperature::degree_celsius;
+
+const MIN_VOLTS: f32 = -0.55;
+const MAX_VOLTS: f32 = 1.50;
+const SCALE_FACTOR: f32 = 100.0;
+
+#[inline]
+pub fn convert(
+    voltage: f32::ElectricPotential,
+) -> Result<f32::ThermodynamicTemperature, InvalidValue> {
+    let volts = voltage.get::<volt>();
+
+    if volts >= MIN_VOLTS && volts <= MAX_VOLTS {
+        let celsius = volts * SCALE_FACTOR;
+        Ok(f32::ThermodynamicTemperature::new::<degree_celsius>(celsius))
+    } else {
+        Err(InvalidValue)
+    }
+}

src/transducer/part/mod.rs

@@ -0,0 +1,7 @@
+mod thermocouple;
+
+#[cfg(feature = "lm35")]
+pub mod lm35;
+
+#[cfg(feature = "thermocouple_k")]
+pub use thermocouple::type_k as thermocouple_k;