SNS - Levitation Current Sensor

boards/stm32l432kc/src/tasks/current_levitation.rs

@@ -0,0 +1,28 @@
+use embassy_stm32::adc::Adc;
+use embassy_time::Delay;
+use hyped_sensors::{current_levitation::CurrentLevitation, SensorValueRange::*};
+use defmt_rtt as _;
+
+
+/// Test task that reads the current and prints it to console
+#[embassy_executor::task]
+pub async fn read_current_levitation() -> ! {
+    let p = embassy_stm32::init(Default::default());
+    let adc = Adc::new(p.ADC1, Delay);
+
+    let mut current_levitation_sensor = CurrentLevitation::new(&mut adc);
+
+    loop {
+        match current_levitation_sensor.read() {
+            Safe(value) => {
+                defmt::info!("Current: {} A (safe)", value)
+            }
+            Warning(value) => {
+                defmt::warn!("Current: {} A (warning)", value)
+            }
+            Critical(value) => {
+                defmt::error!("Current: {} A (critical)", value)
+            }
+        }
+    }
+}

lib/sensors/Cargo.toml

@@ -9,6 +9,7 @@ embassy-sync = { version = "0.6.0", features = ["defmt"], git = "https://github.
 hyped_core = { path = "../core" }
 hyped_i2c = { path = "../io/hyped_i2c" }
 hyped_gpio = { path = "../io/hyped_gpio" }
+hyped_adc = { path = "../io/hyped_adc" }
 defmt = "0.3"
 
 [dev-dependencies]

lib/sensors/src/current_levitation.rs

@@ -0,0 +1,52 @@
+use crate::SensorValueRange;
+use hyped_adc::HypedAdc;
+
+/// current_levitation implements the logic to read current from the ACHS-7121 current sensor using the
+/// Hyped ADC trait.
+///
+/// The code constantly reads the channel for a current reading. It then processes this reading into the right format
+/// (as seen on the data sheet) and returns this reading for use.
+///
+/// The ACHS-7121 has a current range of +- 10 A, sensitivity of 185 mV/A.
+/// Assuming we're supplying 5V to the sensor, our off-set is 2.5V in the output reading - note that this offset is given
+/// by the supply voltage divided by 2, so if you change the supply voltage, you'll have to change the offset that we subtract
+/// in the processed_current accordingly.
+///
+/// Data sheet: https://docs.broadcom.com/doc/ACHS-712x-DS
+
+pub struct CurrentLevitation<T: HypedAdc> {
+    adc: T,
+    calculate_bounds: fn(f32) -> SensorValueRange<f32>,
+}
+
+impl<T: HypedAdc> CurrentLevitation<T> {
+    /// Create a new instance of the Current Levitation sensor
+    pub fn new(adc: T) -> CurrentLevitation<T> {
+        CurrentLevitation {
+            adc,
+            calculate_bounds: default_calculate_bounds,
+        }
+    }
+    /// Read the voltage from the Vout Pin and process it before returning it - you have to subtract the voltage offset and divide by the sensitivity
+    pub fn read(&mut self) -> SensorValueRange<f32> {
+        let current = self.adc.read_value() as f32;
+        (self.calculate_bounds)((current - OFFSET) / SENSITIVITY)
+    }
+}
+
+pub fn default_calculate_bounds(value: f32) -> SensorValueRange<f32> {
+    if value <= MIN_AMPS || value >= MAX_AMPS {
+        SensorValueRange::Critical(value)
+    } else if value <= WARN_AMPS_LOW || value >= WARN_AMPS_HIGH {
+        SensorValueRange::Warning(value)
+    } else {
+        SensorValueRange::Safe(value)
+    }
+}
+
+const OFFSET: f32 = 2.5;
+const SENSITIVITY: f32 = 0.185;
+const MIN_AMPS: f32 = 10.0;
+const MAX_AMPS: f32 = -10.0;
+const WARN_AMPS_LOW: f32 = -8.0;
+const WARN_AMPS_HIGH: f32 = 8.0;

lib/sensors/src/lib.rs

@@ -1,5 +1,6 @@
 #![no_std]
 
+pub mod current_levitation;
 pub mod keyence;
 pub mod temperature;
 pub mod time_of_flight;