make some updates

flight/src/hardware/mcp3208/mod.rs

@@ -0,0 +1,39 @@
+use embedded_hal::spi::{Operation, SpiDevice};
+use anyhow::{ensure, Result};
+use crate::hardware::error::SpiError;
+
+pub struct Mcp3208<SPI> {
+    spi: SPI,
+    vref: f64
+}
+
+impl<SPI> Mcp3208<SPI>
+where
+    SPI : SpiDevice<u8>,
+    SPI::Error : Send,
+    SPI::Error : Sync,
+    SPI::Error : 'static,
+{
+    pub fn new(spi: SPI, vref: f64) -> Self {
+        Self {
+            spi,
+            vref
+        }
+    }
+
+    pub fn read_single(&mut self, channel: u8) -> Result<f64> {
+        ensure!(channel < 8, "Invalid Channel {channel}");
+
+        // We don't care what the third byte written is
+        let mut write_bits = [0b00000110, 0b00000000, 0b00000000];
+        write_bits[0] |= (channel.unbounded_shr(2)) & 0xFF;
+        write_bits[1] |= (channel.unbounded_shl(6)) & 0xFF;
+
+        let mut read_bits = [0u8; 3];
+        self.spi.transfer(&mut read_bits, &write_bits).map_err(SpiError)?;
+
+        let value: u16 = u16::from_be_bytes([read_bits[1], read_bits[2]]) & 0x0FFF;
+
+        Ok(((value as f64) / (0xFFF as f64)) * self.vref)
+    }
+}