Limit i_set within range of MAX1968 chip

src/channels.rs

@@ -129,16 +129,7 @@ impl<'a> Channels<'a> {
         voltage
     }
 
-    pub fn set_i(&mut self, channel: usize, mut i_set: ElectricCurrent) -> ElectricCurrent {
-        // Silently clamp i_set to available range of MAX1968 chip
-        let min = ElectricCurrent::new::<ampere>(-3.0);
-        let max = ElectricCurrent::new::<ampere>(3.0);
-        if i_set < min {
-            i_set = min;
-        }
-        if i_set > max {
-            i_set = max;
-        }
+    pub fn set_i(&mut self, channel: usize, i_set: ElectricCurrent) -> ElectricCurrent {
         let vref_meas = match channel.into() {
             0 => self.channel0.vref_meas,
             1 => self.channel1.vref_meas,

src/command_handler.rs

@@ -54,7 +54,8 @@ pub enum Handler {
 pub enum Error {
     ReportError,
     PostFilterRateError,
-    FlashError
+    FlashError,
+    InputOutOfRangeError,
 }
 
 pub type JsonBuffer = Vec<u8, U1024>;
@@ -184,8 +185,14 @@ impl Handler {
     fn set_pwm (socket: &mut TcpSocket, channels: &mut Channels, channel: usize, pin: PwmPin, value: f64) -> Result<Handler, Error> {
         match pin {
             PwmPin::ISet => {
-                channels.channel_state(channel).pid_engaged = false;
                 let current = ElectricCurrent::new::<ampere>(value);
+                let min = ElectricCurrent::new::<ampere>(-3.0);
+                let max = ElectricCurrent::new::<ampere>(3.0);
+                if current < min || current > max {
+                    send_line(socket, b"{\"error\": \"i_set has unit A and should be in range [-3, +3]\"}");
+                    return Err(Error::InputOutOfRangeError);
+                }
+                channels.channel_state(channel).pid_engaged = false;
                 channels.set_i(channel, current);
                 channels.power_up(channel);
             }