CCF_100/InfiniTime
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Float voltage to int (#444)

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* Change voltage float to millivolt integer
* Explain the ADC to milliVolts conversion
This commit is contained in:
Riku Isokoski
2021-07-02 18:30:32 +03:00
committed by GitHub
parent 7075b7f264
commit 38f40034b0
5 changed files with 17 additions and 34 deletions
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14
src/components/battery/BatteryController.cpp
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@@ -55,17 +55,21 @@ void Battery::SaadcInit() {
void Battery::SaadcEventHandler(nrfx_saadc_evt_t const* p_event) {
const float battery_max = 4.18; // maximum voltage of battery ( max charging voltage is 4.21 )
const float battery_min = 3.20; // minimum voltage of battery before shutdown ( depends on the battery )
const uint16_t battery_max = 4180; // maximum voltage of battery ( max charging voltage is 4.21 )
const uint16_t battery_min = 3200; // minimum voltage of battery before shutdown ( depends on the battery )
if (p_event->type == NRFX_SAADC_EVT_DONE) {
APP_ERROR_CHECK(nrfx_saadc_buffer_convert(&saadc_value, 1));
voltage = (static_cast<float>(p_event->data.done.p_buffer[0]) * 2.04f) / (1024 / 3.0f);
voltage = roundf(voltage * 100) / 100;
// A hardware voltage divider divides the battery voltage by 2
// ADC gain is 1/5
// thus adc_voltage = battery_voltage / 2 * gain = battery_voltage / 10
// reference_voltage is 0.6V
// p_event->data.done.p_buffer[0] = (adc_voltage / reference_voltage) * 1024
voltage = p_event->data.done.p_buffer[0] * 6000 / 1024;
percentRemaining = static_cast<int>(((voltage - battery_min) / (battery_max - battery_min)) * 100);
percentRemaining = (voltage - battery_min) * 100 / (battery_max - battery_min);
percentRemaining = std::max(percentRemaining, 0);
percentRemaining = std::min(percentRemaining, 100);

6
src/components/battery/BatteryController.h
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@@ -50,7 +50,7 @@ namespace Pinetime {
return percentRemainingBuffer.GetAverage();
}
float Voltage() const {
uint16_t Voltage() const {
return voltage;
}
@@ -71,7 +71,7 @@ namespace Pinetime {
static constexpr uint32_t chargingPin = 12;
static constexpr uint32_t powerPresentPin = 19;
static constexpr nrf_saadc_input_t batteryVoltageAdcInput = NRF_SAADC_INPUT_AIN7;
float voltage = 0.0f;
uint16_t voltage = 0;
int percentRemaining = -1;
bool isCharging = false;
@@ -86,4 +86,4 @@ namespace Pinetime {
uint8_t samples = 0;
};
}
}
}