calculate i_set current

README.md

@@ -55,7 +55,7 @@ The scope of this setting is per TCP session.
 | `pwm <0/1> max_i_pos <ratio>`    | Set PWM duty cycle for **max_i_pos** to *ampere* |
 | `pwm <0/1> max_i_neg <ratio>`    | Set PWM duty cycle for **max_i_neg** to *ampere* |
 | `pwm <0/1> max_v <ratio>`        | Set PWM duty cycle for **max_v** to *volt*     |
-| `pwm <0/1> <volts>`              | Disengage PID, set **i_set** DAC to *volts*     |
+| `pwm <0/1> <volts>`              | Disengage PID, set **i_set** DAC to *ampere*     |
 | `pwm <0/1> pid`                  | Set PWM to be controlled by PID                 |
 | `pid`                            | Show PID configuration                          |
 | `pid <0/1> target <value>`       | Set the PID controller target                   |

src/channels.rs

@@ -1,9 +1,10 @@
 use stm32f4xx_hal::hal;
 use smoltcp::time::Instant;
 use uom::si::{
-    f64::{ElectricCurrent, ElectricPotential},
+    f64::{ElectricCurrent, ElectricPotential, ElectricalResistance},
     electric_potential::{millivolt, volt},
     electric_current::ampere,
+    electrical_resistance::ohm,
     ratio::ratio,
 };
 use log::info;
@@ -17,6 +18,7 @@ use crate::{
 };
 
 pub const CHANNELS: usize = 2;
+pub const R_SENSE: f64 = 0.05;
 
 // TODO: -pub
 pub struct Channels {
@@ -91,7 +93,28 @@ impl Channels {
     }
 
     /// i_set DAC
-    pub fn set_dac(&mut self, channel: usize, voltage: ElectricPotential) -> (ElectricPotential, ElectricPotential) {
+    fn get_dac(&mut self, channel: usize) -> (ElectricPotential, ElectricPotential) {
+        let dac_factor = match channel.into() {
+            0 => self.channel0.dac_factor,
+            1 => self.channel1.dac_factor,
+            _ => unreachable!(),
+        };
+        let voltage = self.channel_state(channel).dac_value;
+        let max = ElectricPotential::new::<volt>(ad5680::MAX_VALUE as f64 / dac_factor);
+        (voltage, max)
+    }
+
+    pub fn get_i(&mut self, channel: usize) -> (ElectricCurrent, ElectricCurrent) {
+        let vref = self.channel_state(channel).vref;
+        let r_sense = ElectricalResistance::new::<ohm>(R_SENSE);
+        let (voltage, max) = self.get_dac(channel);
+        let i_tec = (voltage - vref) / (10.0 * r_sense);
+        let max = (max - vref) / (10.0 * r_sense);
+        (i_tec, max)
+    }
+
+    /// i_set DAC
+    fn set_dac(&mut self, channel: usize, voltage: ElectricPotential) -> (ElectricPotential, ElectricPotential) {
         let dac_factor = match channel.into() {
             0 => self.channel0.dac_factor,
             1 => self.channel1.dac_factor,
@@ -109,6 +132,16 @@ impl Channels {
         (voltage, max)
     }
 
+    pub fn set_i(&mut self, channel: usize, i_tec: ElectricCurrent) -> (ElectricCurrent, ElectricCurrent) {
+        let vref = self.channel_state(channel).vref;
+        let r_sense = ElectricalResistance::new::<ohm>(R_SENSE);
+        let voltage = i_tec * 10.0 * r_sense + vref;
+        let (voltage, max) = self.set_dac(channel, voltage);
+        let i_tec = (voltage - vref) / (10.0 * r_sense);
+        let max = (max - vref) / (10.0 * r_sense);
+        (i_tec, max)
+    }
+
     pub fn read_dac_feedback(&mut self, channel: usize) -> ElectricPotential {
         match channel {
             0 => {

src/main.rs

@@ -229,7 +229,12 @@ fn main() -> ! {
                                             channel,
                                             if state.pid_engaged { "engaged" } else { "disengaged" }
                                         );
-                                        let _ = writeln!(socket, "- i_set={:.3}", state.dac_value.into_format_args(volt, Abbreviation));
+                                        let i_set = channels.get_i(channel);
+                                        let _ = writeln!(
+                                            socket, "- i_set={:.3} / {:.3}",
+                                            i_set.0.into_format_args(ampere, Abbreviation),
+                                            i_set.1.into_format_args(ampere, Abbreviation),
+                                        );
                                         let max_v = channels.get_max_v(channel);
                                         let _ = writeln!(
                                             socket, "- max_v={:.3} / {:.3}",
@@ -302,13 +307,13 @@ fn main() -> ! {
                                 Command::Pwm { channel, pin: PwmPin::ISet, value } => {
                                     channels.channel_state(channel).pid_engaged = false;
                                     leds.g3.off();
-                                    let voltage = ElectricPotential::new::<volt>(value);
+                                    let current = ElectricCurrent::new::<ampere>(value);
-                                    let (voltage, max) = channels.set_dac(channel, voltage);
+                                    let (current, max) = channels.set_i(channel, current);
                                     let _ = writeln!(
                                         socket, "channel {}: i_set DAC output set to {:.3} / {:.3}",
                                         channel,
-                                        voltage.into_format_args(volt, Abbreviation),
+                                        current.into_format_args(ampere, Abbreviation),
-                                        max.into_format_args(volt, Abbreviation),
+                                        max.into_format_args(ampere, Abbreviation),
                                     );
                                 }
                                 Command::Pwm { channel, pin, value } => {