SNS - ADC Mux

lib/sensors/src/adc_mux.rs

@@ -0,0 +1,72 @@
+use hyped_io::i2c::{HypedI2c, I2cError};
+
+/// ADCMux implements logic to read a specified number of channel registers on the ADC Mux
+/// and report any failures
+///
+/// Data sheet: https://www.ti.com/lit/ds/symlink/adc128d818.pdf
+pub struct ADCMux<T: HypedI2c> {
+    i2c: T,
+    device_address: u8,
+    channels: [Option<u8>; MAX_MUX_CHANNELS],
+    num_channels: usize,
+    max_num_faulty_channels: u8,
+}
+
+impl<T: HypedI2c> ADCMux<T> {
+    /// Create a new instance of the ADC mux sensor and configure it
+    /// num_channels: number of channels to use (up to 8 max)
+    pub fn new(mut i2c: T, device_address: u8, num_channels: usize) -> Result<Self, MuxError> {
+        if num_channels > MAX_MUX_CHANNELS {
+            return Err(MuxError::TooManyChannels);
+        }
+
+        let max_num_faulty_channels = (FAILURE_THRESHOLD * num_channels as f32).round() as u8;
+
+        Ok(Self {
+            i2c,
+            device_address,
+            channels: [None; MAX_MUX_CHANNELS],
+            num_channels,
+            max_num_faulty_channels,
+        })
+    }
+
+    /// Read ADC Mux channels and report any failures
+    pub fn read_data(&mut self) -> Result<[Option<u8>; MAX_MUX_CHANNELS], MuxError> {
+        let mut mux_data = [None; MAX_MUX_CHANNELS];
+        let mut num_faulty_channels = 0;
+
+        for i in 0..self.num_channels {
+            let channel_address = CHANNEL_ADDRESSES[i];
+            match self.i2c.read_byte(self.device_address, channel_address) {
+                Some(data) => mux_data[i] = Some(data),
+                None => {
+                    num_faulty_channels += 1;
+                    if num_faulty_channels > self.max_num_faulty_channels {
+                        return Err(MuxError::TooManyFaultyChannels);
+                    }
+                }
+            }
+        }
+
+        Ok(mux_data)
+    }
+}
+
+/// ADC Mux addresses
+const ADC_MUX_ADDRESS: u8 = 0x1D;
+const CHANNEL_ADDRESSES: [u8; MAX_MUX_CHANNELS] = [
+    0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
+];
+
+/// Possible errors that can occur when interacting with the ADC Mux
+#[derive(Debug)]
+pub enum MuxError {
+    I2cError(I2cError),
+    TooManyFaultyChannels,
+    TooManyChannels,
+}
+
+// Values for error checking
+const FAILURE_THRESHOLD: f32 = 0.25;
+const MAX_MUX_CHANNELS: usize = 8;