thermistor_current_limiter.hpp

// Context: https://github.com/madcowswe/ODrive/pull/419

#include <stdint.h>

struct HwConfig_t {
    // [polynomial and ADC channel]
};

class ThermistorCurrentLimiter {
public:
    virtual void update() = 0;

    float get_current_limit(float user_limit) {
        // [...]
    }

    float temp_;
};

class OnboardThermistorCurrentLimiter : public ThermistorCurrentLimiter {
public:
    struct Config_t {
        // [...]
        // no fields for polynomial and gpio
    };

    OnboardThermistorCurrentLimiter(HwConfig_t hw_config)
        : hw_config_(hw_config) {}

    void update() override {
        const float voltage = get_adc_voltage_channel(hw_config_.adc_channel_);
        const float normalized_voltage = voltage / adc_full_scale;
        temp_ = horner_fma(normalized_voltage,
                           hw_config_.thermistor_poly_coeffs.data(),
                           hw_config_.thermistor_poly_coeffs.size());
    }

    HwConfig_t hw_config_;
    Config_t config_;

    auto make_protocol_definitions() {
        // [...]
    }
};

class OffboardThermistorCurrentLimiter : public ThermistorCurrentLimiter {
public:
    struct Config_t {
        // [...]
        // includes fields for polynomial and gpio
    };

    OffboardThermistorCurrentLimiter(Config_t& config)
        : config_(config) {}

    void update() override {
        const float voltage = get_adc_voltage(config_.gpio_pin);
        const float normalized_voltage = voltage / adc_full_scale;
        temp_ = horner_fma(normalized_voltage,
                           config_.thermistor_poly_coeffs.data(),
                           config_.thermistor_poly_coeffs.size());
    }

    Config_t config_;

    auto make_protocol_definitions() {
        // [...]
    }
};