Changed MKRGSM1400 variant to increase the reliability

Changed input source control register value to avoid module's  hung due to discharge peak
this change increase the reliability  of the SARA when 2G band's are used

Author: Rocketct

variants/mkrgsm1400/variant.cpp

@@ -185,6 +185,21 @@ SERCOM sercom5(SERCOM5);
 #define PMIC_REG01    0x01
 #define PMIC_REG07    0x07
 
+#define PMIC_REG00    0x00
+
+static inline void  set_pmic_isc_register() {
+  PERIPH_WIRE.initMasterWIRE(100000);
+  PERIPH_WIRE.enableWIRE();
+  pinPeripheral(PIN_WIRE_SDA, g_APinDescription[PIN_WIRE_SDA].ulPinType);
+  pinPeripheral(PIN_WIRE_SCL, g_APinDescription[PIN_WIRE_SCL].ulPinType);
+
+  PERIPH_WIRE.startTransmissionWIRE( PMIC_ADDRESS, WIRE_WRITE_FLAG );
+  PERIPH_WIRE.sendDataMasterWIRE(PMIC_REG00);
+  PERIPH_WIRE.sendDataMasterWIRE(0x06);
+
+  PERIPH_WIRE.disableWIRE();
+}
+
 static inline void enable_battery_charging() {
   PERIPH_WIRE.initMasterWIRE(100000);
   PERIPH_WIRE.enableWIRE();
@@ -229,6 +244,7 @@ void initVariant() {
   if (batteryPresent) {
     enable_battery_charging();
   }
+  set_pmic_isc_register();
   disable_battery_fet(!batteryPresent);
 #endif