50ee4244d3
display.cpp:
Optimize battery voltage measurement
While calibrating noticed it is very non-linear
- outsource function to scale using lookup table
- add lookup table to batvoltage measurement
inserted many values to lookup table while testing
currentsensors:
Fix current value jumping around between 0 and 0.2 on display
while standstill
- add parameter snapToZeroThreshold
88 lines
2.2 KiB
C++
88 lines
2.2 KiB
C++
extern "C" {
|
|
#include "hal/timer_types.h"
|
|
#include "esp_log.h"
|
|
}
|
|
|
|
#include <math.h>
|
|
#include "currentsensor.hpp"
|
|
|
|
//tag for logging
|
|
static const char * TAG = "current-sensors";
|
|
|
|
|
|
|
|
//--------------------------
|
|
//------- getVoltage -------
|
|
//--------------------------
|
|
//local function to get average voltage from adc
|
|
float getVoltage(adc1_channel_t adc, uint32_t samples){
|
|
//measure voltage
|
|
int measure = 0;
|
|
for (int j=0; j<samples; j++){
|
|
measure += adc1_get_raw(adc);
|
|
ets_delay_us(50);
|
|
}
|
|
return (float)measure / samples / 4096 * 3.3;
|
|
}
|
|
|
|
|
|
|
|
//=============================
|
|
//======== constructor ========
|
|
//=============================
|
|
currentSensor::currentSensor (adc1_channel_t adcChannel_f, float ratedCurrent_f, float snapToZeroThreshold_f, bool isInverted_f){
|
|
//copy config
|
|
adcChannel = adcChannel_f;
|
|
ratedCurrent = ratedCurrent_f;
|
|
isInverted = isInverted_f;
|
|
snapToZeroThreshold = snapToZeroThreshold_f;
|
|
//init adc
|
|
adc1_config_width(ADC_WIDTH_BIT_12); //max resolution 4096
|
|
adc1_config_channel_atten(adcChannel, ADC_ATTEN_DB_11); //max voltage
|
|
//calibrate
|
|
calibrateZeroAmpere();
|
|
}
|
|
|
|
|
|
|
|
//============================
|
|
//=========== read ===========
|
|
//============================
|
|
float currentSensor::read(void){
|
|
//measure voltage
|
|
voltage = getVoltage(adcChannel, 30);
|
|
|
|
//scale voltage to current
|
|
if (voltage < centerVoltage){
|
|
current = (1 - voltage / centerVoltage) * -ratedCurrent;
|
|
} else if (voltage > centerVoltage){
|
|
current = (voltage - centerVoltage) / (3.3 - centerVoltage) * ratedCurrent;
|
|
}else {
|
|
current = 0;
|
|
}
|
|
|
|
if (fabs(current) < snapToZeroThreshold)
|
|
{
|
|
ESP_LOGD(TAG, "current=%.3f < threshold=%.3f -> snap to 0", current, snapToZeroThreshold);
|
|
current = 0;
|
|
}
|
|
// invert calculated current if necessary
|
|
else if (isInverted)
|
|
current = -current;
|
|
|
|
ESP_LOGI(TAG, "read sensor adc=%d: voltage=%.3fV, centerVoltage=%.3fV => current=%.3fA", (int)adcChannel, voltage, centerVoltage, current);
|
|
return current;
|
|
}
|
|
|
|
|
|
|
|
//===============================
|
|
//===== calibrateZeroAmpere =====
|
|
//===============================
|
|
void currentSensor::calibrateZeroAmpere(void){
|
|
//measure voltage
|
|
float prev = centerVoltage;
|
|
centerVoltage = getVoltage(adcChannel, 100);
|
|
ESP_LOGW(TAG, "defined centerVoltage (0A) to %.3f (previous %.3f)", centerVoltage, prev);
|
|
}
|