Show and save set value for PWM limits

Show in PwmSummary the set value, before all PWM duty calculations
instead of the machine value after the calculations. Also save the set
value into the flash store instead of the machine value.

README.md

@@ -92,40 +92,43 @@ ADC input data is provided in reports. Query for the latest report with the comm
 Send commands as simple text string terminated by `\n`. Responses are
 formatted as line-delimited JSON.
 
-| Syntax                           | Function                                                                      |
-|----------------------------------|-------------------------------------------------------------------------------|
-| `report`                         | Show current input                                                            |
-| `pwm`                            | Show current PWM settings                                                     |
-| `pwm <0/1> max_i_pos <amp>`      | Set maximum positive output current                                           |
-| `pwm <0/1> max_i_neg <amp>`      | Set maximum negative output current                                           |
-| `pwm <0/1> max_v <volt>`         | Set maximum output voltage                                                    |
-| `pwm <0/1> i_set <amp>`          | Disengage PID, set fixed output current                                       |
-| `pwm <0/1> pid`                  | Let output current to be controlled by the PID                                |
-| `center <0/1> <volt>`            | Set the MAX1968 0A-centerpoint to the specified fixed voltage                 |
-| `center <0/1> vref`              | Set the MAX1968 0A-centerpoint to measure from VREF                           |
-| `pid`                            | Show PID configuration                                                        |
-| `pid <0/1> target <deg_celsius>` | Set the PID controller target temperature                                     |
-| `pid <0/1> kp <value>`           | Set proportional gain                                                         |
-| `pid <0/1> ki <value>`           | Set integral gain                                                             |
-| `pid <0/1> kd <value>`           | Set differential gain                                                         |
-| `pid <0/1> output_min <amp>`     | Set mininum output                                                            |
-| `pid <0/1> output_max <amp>`     | Set maximum output                                                            |
-| `s-h`                            | Show Steinhart-Hart equation parameters                                       |
-| `s-h <0/1> <t0/b/r0> <value>`    | Set Steinhart-Hart parameter for a channel                                    |
-| `postfilter`                     | Show postfilter settings                                                      |
-| `postfilter <0/1> off`           | Disable postfilter                                                            |
-| `postfilter <0/1> rate <rate>`   | Set postfilter output data rate                                               |
-| `load [0/1]`                     | Restore configuration for channel all/0/1 from flash                          |
-| `save [0/1]`                     | Save configuration for channel all/0/1 to flash                               |
-| `reset`                          | Reset the device                                                              |
-| `dfu`                            | Reset device and enters USB device firmware update (DFU) mode                 |
-| `ipv4 <X.X.X.X/L> [Y.Y.Y.Y]`     | Configure IPv4 address, netmask length, and optional default gateway          |
-| `fan`                            | Show current fan settings and sensors' measurements                           |
-| `fan <value>`                    | Set fan power with values from 1 to 100                                       |
-| `fan auto`                       | Enable automatic fan speed control                                            |
-| `fcurve <a> <b> <c>`             | Set fan controller curve coefficients (see *Fan control* section)             |
-| `fcurve default`                 | Set fan controller curve coefficients to defaults (see *Fan control* section) |
-| `hwrev`                          | Show hardware revision, and settings related to it                            |
+| Syntax                                     | Function                                                                      |
+|------------------------------------------- |-------------------------------------------------------------------------------|
+| `report`                                   | Show current input                                                            |
+| `report mode`                              | Show current report mode                                                      |
+| `report mode <off/on>`                     | Set report mode                                                               |
+| `pwm`                                      | Show current PWM settings                                                     |
+| `pwm <0/1> max_i_pos <amp>`                | Set maximum positive output current, clamped to [0, 2]                        |
+| `pwm <0/1> max_i_neg <amp>`                | Set maximum negative output current, clamped to [0, 2]                        |
+| `pwm <0/1> max_v <volt>`                   | Set maximum output voltage, clamped to [0, 4]                                 |
+| `pwm <0/1> i_set <amp>`                    | Disengage PID, set fixed output current, clamped to [-2, 2]                   |
+| `pwm <0/1> polarity <normal/reversed>`     | Set output current polarity, with 'normal' being the front panel polarity     |
+| `pwm <0/1> pid`                            | Let output current to be controlled by the PID                                |
+| `center <0/1> <volt>`                      | Set the MAX1968 0A-centerpoint to the specified fixed voltage                 |
+| `center <0/1> vref`                        | Set the MAX1968 0A-centerpoint to measure from VREF                           |
+| `pid`                                      | Show PID configuration                                                        |
+| `pid <0/1> target <deg_celsius>`           | Set the PID controller target temperature                                     |
+| `pid <0/1> kp <value>`                     | Set proportional gain                                                         |
+| `pid <0/1> ki <value>`                     | Set integral gain                                                             |
+| `pid <0/1> kd <value>`                     | Set differential gain                                                         |
+| `pid <0/1> output_min <amp>`               | Set mininum output                                                            |
+| `pid <0/1> output_max <amp>`               | Set maximum output                                                            |
+| `s-h`                                      | Show Steinhart-Hart equation parameters                                       |
+| `s-h <0/1> <t0/b/r0> <value>`              | Set Steinhart-Hart parameter for a channel                                    |
+| `postfilter`                               | Show postfilter settings                                                      |
+| `postfilter <0/1> off`                     | Disable postfilter                                                            |
+| `postfilter <0/1> rate <rate>`             | Set postfilter output data rate                                               |
+| `load [0/1]`                               | Restore configuration for channel all/0/1 from flash                          |
+| `save [0/1]`                               | Save configuration for channel all/0/1 to flash                               |
+| `reset`                                    | Reset the device                                                              |
+| `dfu`                                      | Reset device and enters USB device firmware update (DFU) mode                 |
+| `ipv4 <X.X.X.X/L> [Y.Y.Y.Y]`               | Configure IPv4 address, netmask length, and optional default gateway          |
+| `fan`                                      | Show current fan settings and sensors' measurements                           |
+| `fan <value>`                              | Set fan power with values from 1 to 100                                       |
+| `fan auto`                                 | Enable automatic fan speed control                                            |
+| `fcurve <a> <b> <c>`                       | Set fan controller curve coefficients (see *Fan control* section)             |
+| `fcurve default`                           | Set fan controller curve coefficients to defaults (see *Fan control* section) |
+| `hwrev`                                    | Show hardware revision, and settings related to it                            |
 
 
 ## USB
@@ -182,6 +185,8 @@ postfilter rate can be tuned with the `postfilter` command.
 
 When using a TEC module with the Thermostat, the Thermostat expects the thermal load (where the thermistor is located) to cool down with a positive software current set point, and heat up with a negative current set point.
 
+If the Thermostat is used for temperature control with the Sinara 5432 DAC "Zotino", and is connected via an IDC cable, the TEC polarity may need to be reversed with the `pwm <ch> polarity reversed` TCP command.
+
 Testing heat flow direction with a low set current is recommended before installation of the TEC module.
 
 ### Limits

pytec/pytec/client.py

@@ -16,7 +16,7 @@ class Client:
         pwm_report = self.get_pwm()
         for pwm_channel in pwm_report:
             for limit in ["max_i_neg", "max_i_pos", "max_v"]:
-                if pwm_channel[limit]["value"] == 0.0:
+                if pwm_channel[limit] == 0.0:
                     logging.warning("`{}` limit is set to zero on channel {}".format(limit, pwm_channel["channel"]))
 
     def _read_line(self):
@@ -53,16 +53,18 @@ class Client:
         Example::
             [{'channel': 0,
               'center': 'vref',
-              'i_set': {'max': 2.9802790335151985, 'value': -0.02002179650216762},
-              'max_i_neg': {'max': 3.0, 'value': 3.0},
-              'max_v': {'max': 5.988, 'value': 5.988},
-              'max_i_pos': {'max': 3.0, 'value': 3.0}},
+              'i_set': -0.02002179650216762,
+              'max_i_neg': 2.0,
+              'max_v': 3.988,
+              'max_i_pos': 2.0,
+              'polarity': 'normal',
              {'channel': 1,
               'center': 'vref',
-              'i_set': {'max': 2.9802790335151985, 'value': -0.02002179650216762},
-              'max_i_neg': {'max': 3.0, 'value': 3.0},
-              'max_v': {'max': 5.988, 'value': 5.988},
-              'max_i_pos': {'max': 3.0, 'value': 3.0}}
+              'i_set': -0.02002179650216762,
+              'max_i_neg': 2.0,
+              'max_v': 3.988,
+              'max_i_pos': 2.0}
+              'polarity': 'normal',
             ]
         """
         return self._get_conf("pwm")

src/channel_state.rs

@@ -16,8 +16,9 @@ use uom::si::{
 use crate::{
     ad7172,
     pid,
+    config::PwmLimits,
     steinhart_hart as sh,
-    command_parser::CenterPoint,
+    command_parser::{CenterPoint, Polarity},
 };
 
 const R_INNER: f64 = 2.0 * 5100.0;
@@ -32,9 +33,11 @@ pub struct ChannelState {
     pub center: CenterPoint,
     pub dac_value: ElectricPotential,
     pub i_set: ElectricCurrent,
+    pub pwm_limits: PwmLimits,
     pub pid_engaged: bool,
     pub pid: pid::Controller,
     pub sh: sh::Parameters,
+    pub polarity: Polarity,
 }
 
 impl ChannelState {
@@ -48,9 +51,15 @@ impl ChannelState {
             center: CenterPoint::Vref,
             dac_value: ElectricPotential::new::<volt>(0.0),
             i_set: ElectricCurrent::new::<ampere>(0.0),
+            pwm_limits: PwmLimits {
+                max_v: 0.0,
+                max_i_pos: 0.0,
+                max_i_neg: 0.0,
+            },
             pid_engaged: false,
             pid: pid::Controller::new(pid::Parameters::default()),
             sh: sh::Parameters::default(),
+            polarity: Polarity::Normal,
         }
     }
 

src/channels.rs

@@ -17,7 +17,7 @@ use crate::{
     ad7172,
     channel::{Channel, Channel0, Channel1},
     channel_state::ChannelState,
-    command_parser::{CenterPoint, PwmPin},
+    command_parser::{CenterPoint, PwmPin, Polarity},
     command_handler::JsonBuffer,
     pins::{self, Channel0VRef, Channel1VRef},
     steinhart_hart,
@@ -158,6 +158,11 @@ impl Channels {
 
     pub fn set_i(&mut self, channel: usize, i_set: ElectricCurrent) -> ElectricCurrent {
         let i_set = i_set.min(MAX_TEC_I).max(-MAX_TEC_I);
+        self.channel_state(channel).i_set = i_set;
+        let negate = match self.channel_state(channel).polarity {
+            Polarity::Normal => 1.0,
+            Polarity::Reversed => -1.0,
+        };
         let vref_meas = match channel.into() {
             0 => self.channel0.vref_meas,
             1 => self.channel1.vref_meas,
@@ -165,10 +170,9 @@ impl Channels {
         };
         let center_point = vref_meas;
         let r_sense = ElectricalResistance::new::<ohm>(R_SENSE);
-        let voltage = i_set * 10.0 * r_sense + center_point;
+        let voltage = negate * i_set * 10.0 * r_sense + center_point;
         let voltage = self.set_dac(channel, voltage);
-        let i_set = (voltage - center_point) / (10.0 * r_sense);
-        self.channel_state(channel).i_set = i_set;
+        let i_set = negate * (voltage - center_point) / (10.0 * r_sense);
         i_set
     }
 
@@ -353,51 +357,25 @@ impl Channels {
         }
     }
 
-    fn get_pwm(&self, channel: usize, pin: PwmPin) -> f64 {
-        fn get<P: hal::PwmPin<Duty=u16>>(pin: &P) -> f64 {
-            let duty = pin.get_duty();
-            let max = pin.get_max_duty();
-            duty as f64 / (max as f64)
-        }
-        match (channel, pin) {
-            (_, PwmPin::ISet) =>
-                panic!("i_set is no pwm pin"),
-            (0, PwmPin::MaxIPos) =>
-                get(&self.pwm.max_i_pos0),
-            (0, PwmPin::MaxINeg) =>
-                get(&self.pwm.max_i_neg0),
-            (0, PwmPin::MaxV) =>
-                get(&self.pwm.max_v0),
-            (1, PwmPin::MaxIPos) =>
-                get(&self.pwm.max_i_pos1),
-            (1, PwmPin::MaxINeg) =>
-                get(&self.pwm.max_i_neg1),
-            (1, PwmPin::MaxV) =>
-                get(&self.pwm.max_v1),
-            _ =>
-                unreachable!(),
-        }
+    pub fn get_max_v(&mut self, channel: usize) -> ElectricPotential {
+        ElectricPotential::new::<volt>(self.channel_state(channel).pwm_limits.max_v)
     }
 
-    pub fn get_max_v(&mut self, channel: usize) -> (ElectricPotential, ElectricPotential) {
-        let max = 4.0 * ElectricPotential::new::<volt>(3.3);
-        let duty = self.get_pwm(channel, PwmPin::MaxV);
-        (duty * max, MAX_TEC_V)
+    pub fn get_max_i_pos(&mut self, channel: usize) -> ElectricCurrent {
+        ElectricCurrent::new::<ampere>(self.channel_state(channel).pwm_limits.max_i_pos)
     }
 
-    pub fn get_max_i_pos(&mut self, channel: usize) -> (ElectricCurrent, ElectricCurrent) {
-        let duty = self.get_pwm(channel, PwmPin::MaxIPos);
-        (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, MAX_TEC_I)
-    }
-
-    pub fn get_max_i_neg(&mut self, channel: usize) -> (ElectricCurrent, ElectricCurrent) {
-        let duty = self.get_pwm(channel, PwmPin::MaxINeg);
-        (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, MAX_TEC_I)
+    pub fn get_max_i_neg(&mut self, channel: usize) -> ElectricCurrent {
+        ElectricCurrent::new::<ampere>(self.channel_state(channel).pwm_limits.max_i_neg)
     }
 
     // Get current passing through TEC
     pub fn get_tec_i(&mut self, channel: usize) -> ElectricCurrent {
-        (self.adc_read(channel, PinsAdcReadTarget::ITec, 16) - self.adc_read(channel, PinsAdcReadTarget::VREF, 16)) / ElectricalResistance::new::<ohm>(0.4)
+        let tec_i = (self.adc_read(channel, PinsAdcReadTarget::ITec, 16) - self.adc_read(channel, PinsAdcReadTarget::VREF, 16)) / ElectricalResistance::new::<ohm>(0.4);
+        match self.channel_state(channel).polarity {
+            Polarity::Normal => tec_i,
+            Polarity::Reversed => -tec_i,
+        }
     }
 
     // Get voltage across TEC
@@ -434,25 +412,50 @@ impl Channels {
 
     pub fn set_max_v(&mut self, channel: usize, max_v: ElectricPotential) -> (ElectricPotential, ElectricPotential) {
         let max = 4.0 * ElectricPotential::new::<volt>(3.3);
-        let duty = (max_v.min(MAX_TEC_V).max(ElectricPotential::zero()) / max).get::<ratio>();
+        let max_v = max_v.min(MAX_TEC_V).max(ElectricPotential::zero());
+        let duty = (max_v / max).get::<ratio>();
         let duty = self.set_pwm(channel, PwmPin::MaxV, duty);
+        self.channel_state(channel).pwm_limits.max_v = max_v.get::<volt>();
         (duty * max, max)
     }
 
     pub fn set_max_i_pos(&mut self, channel: usize, max_i_pos: ElectricCurrent) -> (ElectricCurrent, ElectricCurrent) {
         let max = ElectricCurrent::new::<ampere>(3.0);
-        let duty = (max_i_pos.min(MAX_TEC_I).max(ElectricCurrent::zero()) / MAX_TEC_I_DUTY_TO_CURRENT_RATE).get::<ratio>();
-        let duty = self.set_pwm(channel, PwmPin::MaxIPos, duty);
+        let max_i_pos = max_i_pos.min(MAX_TEC_I).max(ElectricCurrent::zero());
+        let duty = (max_i_pos / MAX_TEC_I_DUTY_TO_CURRENT_RATE).get::<ratio>();
+        let duty = match self.channel_state(channel).polarity {
+            Polarity::Normal => self.set_pwm(channel, PwmPin::MaxIPos, duty),
+            Polarity::Reversed => self.set_pwm(channel, PwmPin::MaxINeg, duty),
+        };
+        self.channel_state(channel).pwm_limits.max_i_pos = max_i_pos.get::<ampere>();
         (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, max)
     }
 
     pub fn set_max_i_neg(&mut self, channel: usize, max_i_neg: ElectricCurrent) -> (ElectricCurrent, ElectricCurrent) {
         let max = ElectricCurrent::new::<ampere>(3.0);
-        let duty = (max_i_neg.min(MAX_TEC_I).max(ElectricCurrent::zero()) / MAX_TEC_I_DUTY_TO_CURRENT_RATE).get::<ratio>();
-        let duty = self.set_pwm(channel, PwmPin::MaxINeg, duty);
+        let max_i_neg = max_i_neg.min(MAX_TEC_I).max(ElectricCurrent::zero());
+        let duty = (max_i_neg / MAX_TEC_I_DUTY_TO_CURRENT_RATE).get::<ratio>();
+        let duty = match self.channel_state(channel).polarity {
+            Polarity::Normal => self.set_pwm(channel, PwmPin::MaxINeg, duty),
+            Polarity::Reversed => self.set_pwm(channel, PwmPin::MaxIPos, duty),
+        };
+        self.channel_state(channel).pwm_limits.max_i_neg = max_i_neg.get::<ampere>();
         (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, max)
     }
 
+    pub fn set_polarity(&mut self, channel: usize, polarity: Polarity) {
+        if self.channel_state(channel).polarity != polarity {
+            let i_set = self.channel_state(channel).i_set;
+            let max_i_pos = self.get_max_i_pos(channel);
+            let max_i_neg = self.get_max_i_neg(channel);
+            self.channel_state(channel).polarity = polarity;
+
+            self.set_i(channel, i_set);
+            self.set_max_i_pos(channel, max_i_pos);
+            self.set_max_i_neg(channel, max_i_neg);
+        }
+    }
+
     fn report(&mut self, channel: usize) -> Report {
         let i_set = self.get_i(channel);
         let i_tec = self.adc_read(channel, PinsAdcReadTarget::ITec, 16);
@@ -508,10 +511,11 @@ impl Channels {
         PwmSummary {
             channel,
             center: CenterPointJson(self.channel_state(channel).center.clone()),
-            i_set: (self.get_i(channel), MAX_TEC_I).into(),
-            max_v: self.get_max_v(channel).into(),
-            max_i_pos: self.get_max_i_pos(channel).into(),
-            max_i_neg: self.get_max_i_neg(channel).into(),
+            i_set: self.get_i(channel),
+            max_v: self.get_max_v(channel),
+            max_i_pos: self.get_max_i_pos(channel),
+            max_i_neg: self.get_max_i_neg(channel),
+            polarity: PolarityJson(self.channel_state(channel).polarity.clone()),
         }
     }
 
@@ -593,15 +597,18 @@ impl Serialize for CenterPointJson {
     }
 }
 
-#[derive(Serialize)]
-pub struct PwmSummaryField<T: Serialize> {
-    value: T,
-    max: T,
-}
+pub struct PolarityJson(Polarity);
 
-impl<T: Serialize> From<(T, T)> for PwmSummaryField<T> {
-    fn from((value, max): (T, T)) -> Self {
-        PwmSummaryField { value, max }
+// used in JSON encoding, not for config
+impl Serialize for PolarityJson {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(match self.0 {
+            Polarity::Normal => "normal",
+            Polarity::Reversed => "reversed",
+        })
     }
 }
 
@@ -609,10 +616,11 @@ impl<T: Serialize> From<(T, T)> for PwmSummaryField<T> {
 pub struct PwmSummary {
     channel: usize,
     center: CenterPointJson,
-    i_set: PwmSummaryField<ElectricCurrent>,
-    max_v: PwmSummaryField<ElectricPotential>,
-    max_i_pos: PwmSummaryField<ElectricCurrent>,
-    max_i_neg: PwmSummaryField<ElectricCurrent>,
+    i_set: ElectricCurrent,
+    max_v: ElectricPotential,
+    max_i_pos: ElectricCurrent,
+    max_i_neg: ElectricCurrent,
+    polarity: PolarityJson,
 }
 
 #[derive(Serialize)]

src/command_handler.rs

@@ -11,7 +11,8 @@ use super::{
         CenterPoint, 
         PidParameter, 
         PwmPin, 
-        ShParameter
+        ShParameter,
+        Polarity
     },
     ad7172,
     CHANNEL_CONFIG_KEY,
@@ -170,6 +171,12 @@ impl Handler {
         Ok(Handler::Handled)
     }
 
+    fn set_polarity(socket: &mut TcpSocket, channels: &mut Channels, channel: usize, polarity: Polarity) -> Result<Handler, Error> {
+        channels.set_polarity(channel, polarity);
+        send_line(socket, b"{}");
+        Ok(Handler::Handled)
+    }
+
     fn set_pwm (socket: &mut TcpSocket, channels: &mut Channels, channel: usize, pin: PwmPin, value: f64) -> Result<Handler, Error> {
         match pin {
             PwmPin::ISet => {
@@ -411,6 +418,7 @@ impl Handler {
             Command::Show(ShowCommand::PostFilter) => Handler::show_post_filter(socket, channels),
             Command::Show(ShowCommand::Ipv4) => Handler::show_ipv4(socket, ipv4_config),
             Command::PwmPid { channel } => Handler::engage_pid(socket, channels, channel),
+            Command::PwmPolarity { channel, polarity } => Handler::set_polarity(socket, channels, channel, polarity),
             Command::Pwm { channel, pin, value } => Handler::set_pwm(socket, channels, channel, pin, value),
             Command::CenterPoint { channel, center } => Handler::set_center_point(socket, channels, channel, center),
             Command::Pid { channel, parameter, value } => Handler::set_pid(socket, channels, channel, parameter, value),

src/command_parser.rs

@@ -135,6 +135,12 @@ pub enum CenterPoint {
     Override(f32),
 }
 
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum Polarity {
+    Normal,
+    Reversed,
+}
+
 #[derive(Debug, Clone, PartialEq)]
 pub enum Command {
     Quit,
@@ -157,6 +163,10 @@ pub enum Command {
     PwmPid {
         channel: usize,
     },
+    PwmPolarity {
+        channel: usize,
+        polarity: Polarity,
+    },
     CenterPoint {
         channel: usize,
         center: CenterPoint,
@@ -297,6 +307,18 @@ fn pwm_pid(input: &[u8]) -> IResult<&[u8], ()> {
     value((), tag("pid"))(input)
 }
 
+fn pwm_polarity(input: &[u8]) -> IResult<&[u8], Polarity> {
+    preceded(
+        tag("polarity"),
+        preceded(
+            whitespace,
+            alt((value(Polarity::Normal, tag("normal")),
+                 value(Polarity::Reversed, tag("reversed"))
+            ))
+        )
+    )(input)
+}
+
 fn pwm(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
     let (input, _) = tag("pwm")(input)?;
     alt((
@@ -309,6 +331,10 @@ fn pwm(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
                     let (input, ()) = pwm_pid(input)?;
                     Ok((input, Ok(Command::PwmPid { channel })))
                 },
+                |input| {
+                    let (input, polarity) = pwm_polarity(input)?;
+                    Ok((input, Ok(Command::PwmPolarity { channel, polarity })))
+                },
                 |input| {
                     let (input, config) = pwm_setup(input)?;
                     match config {

src/config.rs

@@ -8,7 +8,7 @@ use uom::si::{
 use crate::{
     ad7172::PostFilter,
     channels::Channels,
-    command_parser::CenterPoint,
+    command_parser::{CenterPoint, Polarity},
     pid,
     steinhart_hart,
 };
@@ -20,6 +20,7 @@ pub struct ChannelConfig {
     pid_target: f32,
     pid_engaged: bool,
     i_set: ElectricCurrent,
+    polarity: Polarity,
     sh: steinhart_hart::Parameters,
     pwm: PwmLimits,
     /// uses variant `PostFilter::Invalid` instead of `None` to save space
@@ -45,7 +46,8 @@ impl ChannelConfig {
             pid: state.pid.parameters.clone(),
             pid_target: state.pid.target as f32,
             pid_engaged: state.pid_engaged,
-            i_set: i_set,
+            i_set,
+            polarity: state.polarity.clone(),
             sh: state.sh.clone(),
             pwm,
             adc_postfilter,
@@ -68,21 +70,22 @@ impl ChannelConfig {
         };
         let _ = channels.adc.set_postfilter(channel as u8, adc_postfilter);
         let _ = channels.set_i(channel, self.i_set);
+        channels.set_polarity(channel, self.polarity.clone());
     }
 }
 
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
-struct PwmLimits {
-    max_v: f64,
-    max_i_pos: f64,
-    max_i_neg: f64,
+pub struct PwmLimits {
+    pub max_v: f64,
+    pub max_i_pos: f64,
+    pub max_i_neg: f64,
 }
 
 impl PwmLimits {
     pub fn new(channels: &mut Channels, channel: usize) -> Self {
-        let (max_v, _) = channels.get_max_v(channel);
-        let (max_i_pos, _) = channels.get_max_i_pos(channel);
-        let (max_i_neg, _) = channels.get_max_i_neg(channel);
+        let max_v = channels.get_max_v(channel);
+        let max_i_pos = channels.get_max_i_pos(channel);
+        let max_i_neg = channels.get_max_i_neg(channel);
         PwmLimits {
             max_v: max_v.get::<volt>(),
             max_i_pos: max_i_pos.get::<ampere>(),