kirdy/src/thermostat/thermostat.rs

use core::marker::PhantomData;
use crate::sys_timer;
use crate::thermostat::ad5680;
use crate::thermostat::max1968::{MAX1968, AdcReadTarget, PwmPinsEnum};
use log::info;
use uom::si::{
    electric_current::ampere,
    electric_potential::{millivolt, volt},
    electrical_resistance::ohm,
    f64::{ElectricCurrent, ElectricPotential, ElectricalResistance},
    ratio::ratio,
};

pub const R_SENSE: ElectricalResistance = ElectricalResistance {
    dimension: PhantomData,
    units: PhantomData,
    value: 0.05,
};

// Rev 0_2: DAC Chip connects 3V3 reference voltage and thus provide 0-3.3V output range
// TODO: Rev 0_3: DAC Chip connects 3V3 reference voltage,
//      which is then passed through a resistor divider to provide 0-3V output range
pub const DAC_OUT_V_MAX: f64 = 3.3;
pub const TEC_VSEC_BIAS_V: ElectricPotential = ElectricPotential {
    dimension: PhantomData,
    units: PhantomData,
    value: 1.65,
};

// Kirdy Design Specs:
// MaxV = 5.0V
// MAX Current = +- 1.0A
const MAX_V_DUTY_TO_CURRENT_RATE: ElectricPotential = ElectricPotential {
    dimension: PhantomData,
    units: PhantomData,
    value: 4.0 * 3.3,
};
pub const MAX_V_MAX: ElectricPotential = ElectricPotential {
    dimension: PhantomData,
    units: PhantomData,
    value: 5.0,
};
const MAX_V_DUTY_MAX: f64 = MAX_V_MAX.value / MAX_V_DUTY_TO_CURRENT_RATE.value;
const MAX_I_POS_NEG_DUTY_TO_CURRENT_RATE: ElectricCurrent = ElectricCurrent {
    dimension: PhantomData,
    units: PhantomData,
    value: 1.0 / (10.0 * R_SENSE.value / 3.3),
};
pub const MAX_I_POS_CURRENT: ElectricCurrent = ElectricCurrent {
    dimension: PhantomData,
    units: PhantomData,
    value: 1.0,
};
pub const MAX_I_NEG_CURRENT: ElectricCurrent = ElectricCurrent {
    dimension: PhantomData,
    units: PhantomData,
    value: 1.0,
};
// .get::<ratio>() is not implemented for const
const MAX_I_POS_DUTY_MAX: f64 = MAX_I_POS_CURRENT.value / MAX_I_POS_NEG_DUTY_TO_CURRENT_RATE.value;
const MAX_I_NEG_DUTY_MAX: f64 = MAX_I_NEG_CURRENT.value / MAX_I_POS_NEG_DUTY_TO_CURRENT_RATE.value;

pub struct Thermostat {
    max1968: MAX1968,
    // TADC
}

impl Thermostat{
    pub fn new (max1968: MAX1968) -> Self {
        Thermostat{
            max1968
        }
    }
    pub fn setup(&mut self) {
        self.power_down();

        self.calibrate_dac_value();

        self.set_i(ElectricCurrent::new::<ampere>(0.0));

        self.set_max_v(ElectricPotential::new::<volt>(5.0));
        self.set_max_i_pos(ElectricCurrent::new::<ampere>(1.0));
        self.set_max_i_neg(ElectricCurrent::new::<ampere>(1.0));

        self.max1968.power_up();
    }

    pub fn power_up(&mut self){
        self.max1968.power_up();
    }

    pub fn power_down(&mut self){
        self.max1968.power_down();
    }

    pub fn set_i(&mut self, i_tec: ElectricCurrent) -> ElectricCurrent {
        let voltage = i_tec * 10.0 * R_SENSE + self.max1968.phy.center_pt;
        let voltage = self.max1968.set_dac(voltage);
        let i_tec = (voltage - self.max1968.phy.center_pt) / (10.0 * R_SENSE);
        i_tec
    }

    pub fn set_max_v(&mut self, max_v: ElectricPotential) -> ElectricPotential {
        let duty = (max_v / MAX_V_DUTY_TO_CURRENT_RATE).get::<ratio>();
        let duty = self.max1968.set_pwm(PwmPinsEnum::MaxV, duty, MAX_V_DUTY_MAX);
        duty * MAX_V_DUTY_TO_CURRENT_RATE
    }

    pub fn set_max_i_pos(&mut self, max_i_pos: ElectricCurrent) -> ElectricCurrent {
        let duty = (max_i_pos / MAX_I_POS_NEG_DUTY_TO_CURRENT_RATE).get::<ratio>();
        let duty = self.max1968.set_pwm(PwmPinsEnum::MaxPosI, duty, MAX_I_POS_DUTY_MAX);
        duty * MAX_I_POS_NEG_DUTY_TO_CURRENT_RATE
    }

    pub fn set_max_i_neg(&mut self, max_i_neg: ElectricCurrent) -> ElectricCurrent {
        let duty = (max_i_neg / MAX_I_POS_NEG_DUTY_TO_CURRENT_RATE).get::<ratio>();
        let duty = self.max1968.set_pwm(PwmPinsEnum::MaxNegI, duty, MAX_I_NEG_DUTY_MAX);
        duty * MAX_I_POS_NEG_DUTY_TO_CURRENT_RATE
    }

    /// Calibrates the DAC output to match vref of the MAX driver to reduce zero-current offset of the MAX driver output.
    ///
    /// The thermostat DAC applies a control voltage signal to the CTLI pin of MAX driver chip to control its output current.
    /// The CTLI input signal is centered around VREF of the MAX chip. Applying VREF to CTLI sets the output current to 0.
    /// 
    /// This calibration routine measures the VREF voltage and the DAC output with the STM32 ADC, and uses a breadth-first     
    /// search to find the DAC setting that will produce a DAC output voltage closest to VREF. This DAC output voltage will 
    /// be stored and used in subsequent i_set routines to bias the current control signal to the measured VREF, reducing 
    /// the offset error of the current control signal.
    ///
    /// The input offset of the STM32 ADC is eliminated by using the same ADC for the measurements, and by only using the
    /// difference in VREF and DAC output for the calibration.
    /// 
    /// This routine should be called only once after boot, repeated reading of the vref signal and changing of the stored 
    /// VREF measurement can introduce significant noise at the current output, degrading the stabilily performance of the
    /// thermostat. 
    pub fn calibrate_dac_value(&mut self) {
        let samples = 50;
        let mut target_voltage = ElectricPotential::new::<volt>(0.0);
        for _ in 0..samples {
            target_voltage = target_voltage + self.max1968.adc_read(AdcReadTarget::VREF, 1);
        }
        target_voltage = target_voltage / samples as f64;
        let mut start_value = 1;
        let mut best_error = ElectricPotential::new::<volt>(100.0);
        for step in (0..18).rev() {
            info!("Step: {} Calibrating", step);
            let mut prev_value = start_value;
            for value in (start_value..=ad5680::MAX_VALUE).step_by(1 << step) {
                //info!("Calibrating");
                self.max1968.phy.dac.set(value).unwrap();
                sys_timer::sleep(5);

                let dac_feedback = self.max1968.adc_read(AdcReadTarget::DacVfb, 64);
                let error = target_voltage - dac_feedback;
                if error < ElectricPotential::new::<volt>(0.0) {
                    break;
                } else if error < best_error {
                    best_error = error;
                    start_value = prev_value;

                    let vref = (value as f64 / ad5680::MAX_VALUE as f64) * ElectricPotential::new::<volt>(DAC_OUT_V_MAX);
                    self.max1968.set_center_point(vref);
                }
                prev_value = value;
            }
        }
    }
    
}