Fix bat voltage: lookup table, currentSensors: Add snap to zero

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

common/currentsensor.cpp

@@ -3,6 +3,7 @@ extern "C" {
 #include "esp_log.h"
 }
 
+#include <math.h>
 #include "currentsensor.hpp"
 
 //tag for logging
@@ -29,11 +30,12 @@ float getVoltage(adc1_channel_t adc, uint32_t samples){
 //=============================
 //======== constructor ========
 //=============================
-currentSensor::currentSensor (adc1_channel_t adcChannel_f, float ratedCurrent_f, bool isInverted_f){
+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
@@ -59,8 +61,14 @@ float currentSensor::read(void){
 		current = 0;
 	}
 
-	//invert calculated current if necessary
-	if (isInverted) current = -current;
+	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;

common/currentsensor.hpp

@@ -7,13 +7,14 @@
 
 class currentSensor{
 	public:
-		currentSensor (adc1_channel_t adcChannel_f, float ratedCurrent, bool inverted = false);
+		currentSensor (adc1_channel_t adcChannel_f, float ratedCurrent, float snapToZeroThreshold, bool inverted = false);
 		void calibrateZeroAmpere(void); //set current voltage to voltage representing 0A
 		float read(void); //get current ampere
 	private:
 		adc1_channel_t adcChannel;
 		float ratedCurrent;
 		bool isInverted;
+		float snapToZeroThreshold;
 		uint32_t measure;
 		float voltage;
 		float current;

common/motorctl.cpp

@@ -29,7 +29,7 @@ void task_motorctl( void * ptrControlledMotor ){
 //=============================
 //constructor, simultaniously initialize instance of motor driver 'motor' and current sensor 'cSensor' with provided config (see below lines after ':')
 controlledMotor::controlledMotor(motorSetCommandFunc_t setCommandFunc,  motorctl_config_t config_control, nvs_handle_t * nvsHandle_f): 
-	cSensor(config_control.currentSensor_adc, config_control.currentSensor_ratedCurrent, config_control.currentInverted) {
+	cSensor(config_control.currentSensor_adc, config_control.currentSensor_ratedCurrent, config_control.currentSnapToZeroThreshold, config_control.currentInverted) {
 		//copy parameters for controlling the motor
 		config = config_control;
 		//pointer to update motot dury method

common/types.hpp

@@ -49,6 +49,7 @@ typedef struct motorctl_config_t {
 	float currentSensor_ratedCurrent;
     float currentMax;
     bool currentInverted;
+    float currentSnapToZeroThreshold;
 	uint32_t deadTimeMs; //time motor stays in IDLE before direction change
 } motorctl_config_t;