nicla-system: Add function for toggling battery NTC.

libraries/Nicla_System/examples/NiclaSenseME_BatteryStatus/NiclaSenseME_BatteryStatus.ino

@@ -163,7 +163,7 @@ void setup()
   nicla::begin(); // initialise library
   nicla::leds.begin(); // Start I2C connection
 
-  nicla::ntc_disabled = false; // Set to true for standard LiPo batteries without NTC
+  nicla::setBatteryNTCEnabled(true); // Set to false if your battery doesn't have an NTC thermistor.
   setupBLE();
 
   nicla::leds.setColor(green);

libraries/Nicla_System/src/Nicla_System.cpp

@@ -14,6 +14,7 @@ BQ25120A nicla::_pmic;
 rtos::Mutex nicla::i2c_mutex;
 bool nicla::started = false;
 uint8_t nicla::_chg_reg = 0;
+bool nicla::_ntcEnabled = true;
 
 void nicla::pingI2CThd() {
   while(1) {
@@ -107,12 +108,6 @@ uint8_t nicla::readLDOreg()
   return _pmic.readByte(BQ25120A_ADDRESS, BQ25120A_LDO_CTRL);
 }
 
-/** 
- * @brief Defines if the connected battery has a negative temperature coefficient (NTC) thermistor.
- * NTCs are used to prevent the batteries from being charged at temperatures that are too high or too low.
- */
-bool nicla::ntc_disabled;
-
 bool nicla::enableCharge(uint8_t mA, bool disable_ntc)
 {
   if (mA < 5) {
@@ -128,8 +123,8 @@ bool nicla::enableCharge(uint8_t mA, bool disable_ntc)
   _pmic.writeByte(BQ25120A_ADDRESS, BQ25120A_ILIM_UVLO_CTRL, 0x3F);
 
   // Disable TS and interrupt on charge
-  ntc_disabled = disable_ntc;
-  if (ntc_disabled) {
+  _ntcEnabled = !disable_ntc;
+  if (!_ntcEnabled) {
     _pmic.writeByte(BQ25120A_ADDRESS, BQ25120A_TS_CONTROL, 1 << 3);
   }
 
@@ -150,6 +145,10 @@ uint16_t nicla::getFault() {
   return tmp;
 }
 
+void nicla::setBatteryNTCEnabled(bool enabled){
+  _ntcEnabled = enabled;
+}
+
 float nicla::getRegulatedBatteryVoltage(){
   /*
   According to https://www.ti.com/lit/ds/symlink/bq25120a.pdf Page 40:
@@ -291,7 +290,7 @@ uint8_t nicla::getBatteryStatus() {
     res = BATTERY_EMPTY;
   }
 
-  if (!ntc_disabled) {
+  if (_ntcEnabled) {
     // Extract bits 5 and 6 (TS_FAULT0 and TS_FAULT1)
     uint8_t temperatureSenseFault = _pmic.readByte(BQ25120A_ADDRESS, BQ25120A_TS_CONTROL) >> 5 & 0b11;
 
@@ -321,6 +320,7 @@ uint8_t nicla::getBatteryStatus() {
 }
 
 uint8_t nicla::getBatteryTemperature() {
+  if(!_ntcEnabled) return BATTERY_TEMPERATURE_NORMAL;
   return getBatteryStatus() & BATTERY_TEMPERATURE_MASK;
 }
 

libraries/Nicla_System/src/Nicla_System.h

@@ -47,6 +47,15 @@ class nicla {
   static uint8_t readLDOreg();
   static bool enableCharge(uint8_t mA = 20, bool disable_ntc = true);
 
+  /**
+   * @brief Enables or disables the negative temperature coefficient (NTC) thermistor.
+   * NTCs are used to prevent the batteries from being charged at temperatures that are too high or too low.
+   * Set to disabled for standard LiPo batteries without NTC.
+   * If your battery has only a plus and minus wire, it does not have an NTC.
+   * The default is enabled.
+   */
+  static void setBatteryNTCEnabled(bool enabled);
+
   /**
    * @brief Get the Regulated Battery Voltage in Volts.
    * 
@@ -93,6 +102,8 @@ class nicla {
    * When the battery is warm, the charging current is reduced by 140 mV.
    * When the battery is unter an extreme temperature (hot or cold), the charging is suspended.
    * @note If the battery doesn't have a negative temperature coefficient (NTC) thermistor, the temperature is always "Normal".
+   * This is not determined automatically and needs to be set using the setBatteryNTCEnabled() function.
+   * @see setBatteryNTCEnabled()
    * @return uint8_t The battery temperature represented by one of the following constants:
    * BATTERY_TEMPERATURE_NORMAL, BATTERY_TEMPERATURE_EXTREME, BATTERY_TEMPERTURE_COOL, BATTERY_TEMPERTURE_WARM
    */
@@ -111,7 +122,6 @@ class nicla {
 
   static uint16_t getFault();
 
-  static bool ntc_disabled;
 
   static RGBled leds;
   static BQ25120A _pmic;
@@ -123,6 +133,8 @@ class nicla {
   static bool started;
 
 private:
+  /// Defines if the connected battery has a negative temperature coefficient (NTC) thermistor.
+  static bool _ntcEnabled;
   static void pingI2CThd();
   static void checkChgReg();
   static rtos::Mutex i2c_mutex;