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#include "components/battery/BatteryController.h"
#include "drivers/PinMap.h"
#include <hal/nrf_gpio.h>
#include <nrfx_saadc.h>
#include <algorithm>
#include <cmath>
using namespace Pinetime::Controllers;
Battery* Battery::instance = nullptr;
Battery::Battery() {
instance = this;
nrf_gpio_cfg_input(PinMap::Charging, static_cast<nrf_gpio_pin_pull_t> GPIO_PIN_CNF_PULL_Disabled);
}
void Battery::ReadPowerState() {
isCharging = !nrf_gpio_pin_read(PinMap::Charging);
isPowerPresent = !nrf_gpio_pin_read(PinMap::PowerPresent);
if (isPowerPresent && !isCharging) {
isFull = true;
} else if (!isPowerPresent) {
isFull = false;
}
}
void Battery::MeasureVoltage() {
ReadPowerState();
if (isReading) {
return;
}
// Non blocking read
isReading = true;
SaadcInit();
nrfx_saadc_sample();
}
void Battery::AdcCallbackStatic(nrfx_saadc_evt_t const* event) {
instance->SaadcEventHandler(event);
}
void Battery::SaadcInit() {
nrfx_saadc_config_t adcConfig = NRFX_SAADC_DEFAULT_CONFIG;
APP_ERROR_CHECK(nrfx_saadc_init(&adcConfig, AdcCallbackStatic));
nrf_saadc_channel_config_t adcChannelConfig = {.resistor_p = NRF_SAADC_RESISTOR_DISABLED,
.resistor_n = NRF_SAADC_RESISTOR_DISABLED,
.gain = NRF_SAADC_GAIN1_4,
.reference = NRF_SAADC_REFERENCE_INTERNAL,
.acq_time = NRF_SAADC_ACQTIME_40US,
.mode = NRF_SAADC_MODE_SINGLE_ENDED,
.burst = NRF_SAADC_BURST_ENABLED,
.pin_p = batteryVoltageAdcInput,
.pin_n = NRF_SAADC_INPUT_DISABLED};
APP_ERROR_CHECK(nrfx_saadc_channel_init(0, &adcChannelConfig));
APP_ERROR_CHECK(nrfx_saadc_buffer_convert(&saadc_value, 1));
}
void Battery::SaadcEventHandler(nrfx_saadc_evt_t const* p_event) {
if (p_event->type == NRFX_SAADC_EVT_DONE) {
APP_ERROR_CHECK(nrfx_saadc_buffer_convert(&saadc_value, 1));
// A hardware voltage divider divides the battery voltage by 2
// ADC gain is 1/4
// thus adc_voltage = battery_voltage / 2 * gain = battery_voltage / 8
// reference_voltage is 600mV
// p_event->data.done.p_buffer[0] = (adc_voltage / reference_voltage) * 1024
voltage = p_event->data.done.p_buffer[0] * (8 * 600) / 1024;
uint8_t newPercent;
if (isFull) {
newPercent = 100;
} else {
newPercent = std::min(GetBatteryPercentageFromVoltage(voltage), static_cast<uint8_t>(isCharging ? 99 : 100));
}
if ((isPowerPresent && newPercent > percentRemaining) || (!isPowerPresent && newPercent < percentRemaining) || firstMeasurement) {
firstMeasurement = false;
percentRemaining = newPercent;
systemTask->PushMessage(System::Messages::BatteryPercentageUpdated);
}
nrfx_saadc_uninit();
isReading = false;
}
}
void Battery::Register(Pinetime::System::SystemTask* systemTask) {
this->systemTask = systemTask;
}
uint8_t Battery::GetBatteryPercentageFromVoltage(uint16_t voltage) {
// The number of line segments used to approximate the battery discharge curve.
static const uint8_t LINE_SEGMENT_COUNT = 7;
// The voltages (mV) at the endpoints of the line segments. Any two consecutive
// values represent the start and end voltage of a line segment.
static const uint16_t voltageOffsets[LINE_SEGMENT_COUNT + 1] {4157, 4063, 3882, 3747, 3716, 3678, 3583, 3500};
// The battery percentages at the endpoints of the line segments. Note that last
// value is omitted: It is not needed because we only need the percentages at
// the start of each line segment.
static const float percentageOffsets[LINE_SEGMENT_COUNT] {100.000, 95.197, 70.429, 48.947, 35.158, 18.971, 5.801};
// The pre-calculated slopes (in battery percentage points per millivolt) of the
// line segments.
static const float percentageSlopes[LINE_SEGMENT_COUNT] {0.05109, 0.13684, 0.15913, 0.44481, 0.42595, 0.13863, 0.06989};
if (voltage >= voltageOffsets[0]) {
return 100;
}
if (voltage <= voltageOffsets[7]) {
return 0;
}
for (uint8_t i = 0; i < LINE_SEGMENT_COUNT; i++) {
if (voltage > voltageOffsets[i + 1]) {
return static_cast<uint8_t>(roundf(percentageOffsets[i] + percentageSlopes[i] * (voltage - voltageOffsets[i])));
}
}
return 0;
}
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