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GitHub Repository: Ardupilot/ardupilot
 Path: blob/master/libraries/AP_BattMonitor/AP_BattMonitor_LTC2946.cpp
Views: 1798
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#include "AP_BattMonitor_config.h"

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#if AP_BATTERY_LTC2946_ENABLED

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#include <GCS_MAVLink/GCS.h>

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#include <AP_HAL/utility/sparse-endian.h>

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#include "AP_BattMonitor_LTC2946.h"

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extern const AP_HAL::HAL& hal;

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#define REG_CTRLA 0x00

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#define REG_CTRLB 0x01

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#define REG_STATUS 0x80

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#define REG_MFR_ID 0xe7

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// first byte of 16 bit ID is stable

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#define ID_LTC2946 0x60

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#define REG_DELTA 0x14 // 16 bits

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#define REG_VIN   0x1e // 16 bits

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#define REGA_CONF 0x18 // sense, alternate

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#define REGB_CONF 0x01 // auto-reset

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void AP_BattMonitor_LTC2946::init(void)

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{

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    dev = hal.i2c_mgr->get_device(HAL_BATTMON_LTC2946_BUS, HAL_BATTMON_LTC2946_ADDR, 100000, false, 20);

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    if (!dev) {

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        return;

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    }

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    uint8_t id = 0;

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    WITH_SEMAPHORE(dev->get_semaphore());

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    if (!dev->read_registers(REG_MFR_ID, &id, 1) || id != ID_LTC2946) {

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        GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "LTC2946: Failed to find device 0x%04x", unsigned(id));

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        return;

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    }

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    if (!dev->write_register(REG_CTRLA, REGA_CONF) ||

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        !dev->write_register(REG_CTRLB, REGB_CONF)) {

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        GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "LTC2946: Failed to configure device");

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        return;

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    }

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    // use datasheet typical values

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    voltage_LSB = 102.4 / 4095.0;

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    current_LSB = (0.1024/0.0005) / 4095.0;

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    GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "LTC2946: found monitor on bus %u", HAL_BATTMON_LTC2946_BUS);

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    if (dev) {

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        dev->register_periodic_callback(25000, FUNCTOR_BIND_MEMBER(&AP_BattMonitor_LTC2946::timer, void));

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    }

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}

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/// read the battery_voltage and current, should be called at 10hz

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void AP_BattMonitor_LTC2946::read(void)

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{

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    WITH_SEMAPHORE(accumulate.sem);

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    _state.healthy = accumulate.count > 0;

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    if (!_state.healthy) {

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        return;

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    }

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    _state.voltage = accumulate.volt_sum / accumulate.count;

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    _state.current_amps = accumulate.current_sum / accumulate.count;

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    accumulate.volt_sum = 0;

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    accumulate.current_sum = 0;

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    accumulate.count = 0;

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    const uint32_t tnow = AP_HAL::micros();

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    const uint32_t dt_us = tnow - _state.last_time_micros;

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    // update total current drawn since startup

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    update_consumed(_state, dt_us);

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    _state.last_time_micros = tnow;

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}

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/*

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 read word from register

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 returns true if read was successful, false if failed

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*/

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bool AP_BattMonitor_LTC2946::read_word(const uint8_t reg, uint16_t& data) const

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{

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    // read the appropriate register from the device

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    if (!dev->read_registers(reg, (uint8_t *)&data, sizeof(data))) {

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        return false;

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    }

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    // convert byte order

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    data = uint16_t(be16toh(uint16_t(data)));

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    // return success

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    return true;

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}

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void AP_BattMonitor_LTC2946::timer(void)

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{

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    uint16_t amps, volts;

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    if (!read_word(REG_DELTA, amps) ||

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        !read_word(REG_VIN, volts)) {

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        return;

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    }

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    WITH_SEMAPHORE(accumulate.sem);

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    // convert 12 bit ADC data

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    accumulate.volt_sum += (volts>>4) * voltage_LSB;

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    accumulate.current_sum += (amps>>4) * current_LSB;

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    accumulate.count++;

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}

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#endif // AP_BATTERY_LTC2946_ENABLED

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