keep shdn high all the time

src/channel.rs

@@ -28,10 +28,12 @@ pub struct Channel<C: ChannelPins> {
 }
 
 impl<C: ChannelPins> Channel<C> {
-    pub fn new(pins: ChannelPinSet<C>) -> Self {
+    pub fn new(mut pins: ChannelPinSet<C>) -> Self {
         let state = ChannelState::default();
         let mut dac = ad5680::Dac::new(pins.dac_spi, pins.dac_sync);
         let _ = dac.set(0);
+        // power up TEC
+        let _ = pins.shdn.set_high();
         // sensible dummy preset. calibrate_i_set() must be used.
         let dac_factor = ad5680::MAX_VALUE as f64 / 5.0;
 

src/channels.rs

@@ -96,12 +96,10 @@ impl Channels {
             0 => {
                 self.channel0.dac.set(value).unwrap();
                 self.channel0.state.dac_value = voltage;
-                self.channel0.shdn.set_high().unwrap();
             }
             1 => {
                 self.channel1.dac.set(value).unwrap();
                 self.channel1.state.dac_value = voltage;
-                self.channel1.shdn.set_high().unwrap();
             }
             _ => unreachable!(),
         }