AP_BattMonitor_AD7091R5.cpp

#include "AP_BattMonitor_AD7091R5.h"

/**
 * @brief You can use it to Read Current and voltage of 1-3 batteries from a ADC extender IC over I2C.
 * AD7091R5 is a ADC extender and we are using it to read current and voltage of multiple batteries.
 * Examples of Pin combination:
 *  1)Pin 50 = Voltage 51,52,53 =  Current. For 3 battery combination Voltage will be same accross.
 *  2)Pin 50,51 = Voltage and Current Battery 1 -   Pin 52,53 = Voltage and Current Battery 2
 * Only the First instance of Battery Monitor will be reading the values from IC over I2C.
 * Make sure you understand the method of calculation used in this driver before using it.
 * e.g. using pin 1 on IC to read voltage of 2 batteries and pin 2 and 3 to read current from individual battery.
 * Pin number represents 50 = pin 1, 51 = pin 2 and so on 52, 53
 * BATT2_Monitor  = 24 ,  BATT3_Monitor  = 24
 * BATT2_VOLT_PIN = 50 ,  BATT3_VOLT_PIN = 50
 * BATT2_CURR_PIN = 51 ,  BATT3_CURR_PIN = 52
 *
 *
 */

#if AP_BATTERY_AD7091R5_ENABLED

#include <AP_HAL/AP_HAL.h>
#include <AP_Common/AP_Common.h>
#include <AP_Math/AP_Math.h>

//macro defines
#define AD7091R5_I2C_ADDR        0x2F // A0 and A1 tied to GND
#define AD7091R5_I2C_BUS         0
#define AD7091R5_RESET           0x02
#define AD7091R5_RESULT_ADDR     0x00
#define AD7091R5_CHAN_ADDR       0x01
#define AD7091R5_CONF_ADDR       0x02
#define AD7091R5_CH_ID(x)        ((x >> 5) & 0x03)
#define AD7091R5_RES_MASK        0x0F
#define AD7091R5_REF             3.3f
#define AD7091R5_RESOLUTION      (float)4096
#define AD7091R5_PERIOD_USEC     100000
#define AD7091R5_BASE_PIN        50


extern const AP_HAL::HAL& hal;
const AP_Param::GroupInfo AP_BattMonitor_AD7091R5::var_info[] = {

    // @Param: VOLT_PIN
    // @DisplayName: Battery Voltage sensing pin on the AD7091R5 Ic
    // @Description: Sets the analog input pin that should be used for voltage monitoring on AD7091R5.
    // @Values: -1:Disabled
    // @User: Standard
    // @RebootRequired: True
    AP_GROUPINFO("VOLT_PIN", 56, AP_BattMonitor_AD7091R5, _volt_pin, 0),

    // @Param: CURR_PIN
    // @DisplayName: Battery Current sensing pin
    // @Description: Sets the analog input pin that should be used for Current monitoring on AD7091R5.
    // @Values: -1:Disabled
    // @User: Standard
    // @RebootRequired: True
    AP_GROUPINFO("CURR_PIN", 57, AP_BattMonitor_AD7091R5, _curr_pin, 0),

    // @Param: VOLT_MULT
    // @DisplayName: Voltage Multiplier
    // @Description: Used to convert the voltage of the voltage sensing pin (@PREFIX@VOLT_PIN) to the actual battery's voltage (pin_voltage * VOLT_MULT).
    // @User: Advanced
    AP_GROUPINFO("VOLT_MULT", 58, AP_BattMonitor_AD7091R5, _volt_multiplier, 0),

    // @Param: AMP_PERVLT
    // @DisplayName: Amps per volt
    // @Description: Number of amps that a 1V reading on the current sensor corresponds to.
    // @Units: A/V
    // @User: Standard
    AP_GROUPINFO("AMP_PERVLT", 59, AP_BattMonitor_AD7091R5, _curr_amp_per_volt, 0),

    // @Param: AMP_OFFSET
    // @DisplayName: AMP offset
    // @Description: Voltage offset at zero current on current sensor
    // @Units: V
    // @User: Standard
    AP_GROUPINFO("AMP_OFFSET", 60, AP_BattMonitor_AD7091R5, _curr_amp_offset, 0),

    // @Param: VLT_OFFSET
    // @DisplayName: Volage offset
    // @Description: Voltage offset on voltage pin. This allows for an offset due to a diode. This voltage is subtracted before the scaling is applied
    // @Units: V
    // @User: Advanced
    AP_GROUPINFO("VLT_OFFSET", 61, AP_BattMonitor_AD7091R5, _volt_offset, 0),

    // CHECK/UPDATE INDEX TABLE IN AP_BattMonitor_Backend.cpp WHEN CHANGING OR ADDING PARAMETERS

    AP_GROUPEND
};


//Variable initialised to read from first instance.
AP_BattMonitor_AD7091R5::AnalogData AP_BattMonitor_AD7091R5::_analog_data[AD7091R5_NO_OF_CHANNELS];
bool AP_BattMonitor_AD7091R5::_first = true;
bool AP_BattMonitor_AD7091R5::_health = false;

/**
 * @brief Construct a new ap battmonitor ad7091r5::ap battmonitor ad7091r5 object
 *
 * @param mon
 * @param mon_state
 * @param params
 */
AP_BattMonitor_AD7091R5::AP_BattMonitor_AD7091R5(AP_BattMonitor &mon,
        AP_BattMonitor::BattMonitor_State &mon_state,
        AP_BattMonitor_Params &params) :
    AP_BattMonitor_Backend(mon, mon_state, params)
{
    AP_Param::setup_object_defaults(this, var_info);
    _state.var_info = var_info;
}

/**
 * @brief probe and initialize the sensor and register call back
 *
 */
void AP_BattMonitor_AD7091R5::init()
{
    // voltage and current pins from params and check if there are in range
    if (_volt_pin.get() >= AD7091R5_BASE_PIN && _volt_pin.get() <= AD7091R5_BASE_PIN + AD7091R5_NO_OF_CHANNELS && 
    _curr_pin.get() >= AD7091R5_BASE_PIN && _curr_pin.get() <= AD7091R5_BASE_PIN + AD7091R5_NO_OF_CHANNELS) {
        volt_buff_pt = _volt_pin.get() - AD7091R5_BASE_PIN;
        curr_buff_pt = _curr_pin.get() - AD7091R5_BASE_PIN;
    }
    else{
        return; //pin values are out of range
    }

    // only the first instance read the i2c device
    if (_first) {
        _first = false;
        // probe i2c device
        _dev = hal.i2c_mgr->get_device(AD7091R5_I2C_BUS, AD7091R5_I2C_ADDR);

        if (_dev) {
            WITH_SEMAPHORE(_dev->get_semaphore());
            _dev->set_retries(10); // lots of retries during probe
            //Reset and config device
            if (_initialize()) {
                _dev->set_retries(2); // drop to 2 retries for runtime
                _dev->register_periodic_callback(AD7091R5_PERIOD_USEC, FUNCTOR_BIND_MEMBER(&AP_BattMonitor_AD7091R5::_read_adc, void));
            }
        }
    }
}

/**
 * @brief read - read the voltage and curren
 *
 */
void AP_BattMonitor_AD7091R5::read()
{

    WITH_SEMAPHORE(sem);
    //copy global health status to all instances
    _state.healthy = _health;

    //return if system not healthy
    if (!_state.healthy) {
        return;
    }

    //voltage conversion
    _state.voltage = (_data_to_volt(_analog_data[volt_buff_pt].data) - _volt_offset) * _volt_multiplier;

    //current amps conversion
    _state.current_amps = (_data_to_volt(_analog_data[curr_buff_pt].data) - _curr_amp_offset) * _curr_amp_per_volt;

    // calculate time since last current read
    uint32_t tnow = AP_HAL::micros();
    uint32_t dt_us = tnow - _state.last_time_micros;

    // update total current drawn since startup
    update_consumed(_state, dt_us);

    // record time
    _state.last_time_micros = tnow;
}

/**
 * @brief read all four channels and store the results
 *
 */
void AP_BattMonitor_AD7091R5::_read_adc()
{
    uint8_t data[AD7091R5_NO_OF_CHANNELS*2];
    //reset and reconfigure IC if health status is not good.
    if (!_state.healthy) {
        _initialize();
    }
    //read value
    bool ret = _dev->transfer(nullptr, 0, data, sizeof(data));
    WITH_SEMAPHORE(sem);
    if (ret) {
        for (int i=0; i<AD7091R5_NO_OF_CHANNELS; i++) {
            uint8_t chan = AD7091R5_CH_ID(data[2*i]);
            _analog_data[chan].data = ((uint16_t)(data[2*i]&AD7091R5_RES_MASK)<<8) | data[2*i+1];
        }
        _health = true;
    } else {
        _health = false;
    }
}

/**
 * @brief config the adc
 *
 * @return true
 * @return false
 */
bool AP_BattMonitor_AD7091R5::_initialize()
{
    //reset the device
    uint8_t data[3] = {AD7091R5_CONF_ADDR, AD7091R5_CONF_CMD | AD7091R5_RESET, AD7091R5_CONF_PDOWN0};

    if(_dev->transfer(data, sizeof(data), nullptr, 0)){
        //command mode, use external 3.3 reference, all channels enabled, set address pointer register to read the adc results
        uint8_t data_2[6] = {AD7091R5_CONF_ADDR, AD7091R5_CONF_CMD, AD7091R5_CONF_PDOWN0, AD7091R5_CHAN_ADDR, AD7091R5_CHAN_ALL, AD7091R5_RESULT_ADDR};
        return _dev->transfer(data_2, sizeof(data_2), nullptr, 0);
    }
    return false;
}

/**
 * @brief convert binary reading to volts
 *
 * @param data
 * @return float
 */
float AP_BattMonitor_AD7091R5::_data_to_volt(uint32_t data)
{
    return (AD7091R5_REF/AD7091R5_RESOLUTION)*data;
}

#endif // AP_BATTERY_AD7091R5_ENABLED