[WIP] Enable battery charging on MKRWAN1310

Since MKRWAN1310 battery sense ADC pin is not connected we must enable the PMIC, check if it starts charging, eventually disable the charging circuitry.
ATM the bootloader is a bit pick and could hang the board on first upload.

Author: facchinm

variants/mkrwan1300/variant.cpp

@@ -172,44 +172,82 @@ const void* g_apTCInstances[TCC_INST_NUM + TC_INST_NUM]={ TCC0, TCC1, TCC2, TC3,
 
 #if defined(USE_BQ24195L_PMIC)
 #include "wiring_private.h"
+#include "delay.h"
 
 #define PMIC_ADDRESS  0x6B
 #define PMIC_REG01    0x01
 #define PMIC_REG07    0x07
+#define PMIC_REG08    0x08
 
 static inline void enable_battery_charging() {
-  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 );
+  bool ret = PERIPH_WIRE.startTransmissionWIRE( PMIC_ADDRESS, WIRE_WRITE_FLAG );
+  if (!ret) {
+    return;
+  }
   PERIPH_WIRE.sendDataMasterWIRE(PMIC_REG01);
   PERIPH_WIRE.sendDataMasterWIRE(0x1B); // Charge Battery + Minimum System Voltage 3.5V
   PERIPH_WIRE.prepareCommandBitsWire(WIRE_MASTER_ACT_STOP);
+}
 
-  PERIPH_WIRE.disableWIRE();
+static inline void disable_battery_charging() {
+
+  bool ret = PERIPH_WIRE.startTransmissionWIRE( PMIC_ADDRESS, WIRE_WRITE_FLAG );
+  if (!ret) {
+    return;
+  }
+  PERIPH_WIRE.sendDataMasterWIRE(PMIC_REG01);
+  PERIPH_WIRE.sendDataMasterWIRE(0x0B); // Charge Battery + Minimum System Voltage 3.5V
+  PERIPH_WIRE.prepareCommandBitsWire(WIRE_MASTER_ACT_STOP);
 }
 
 static inline void disable_battery_fet(bool disabled) {
-  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 );
+  bool ret = PERIPH_WIRE.startTransmissionWIRE( PMIC_ADDRESS, WIRE_WRITE_FLAG );
+  if (!ret) {
+    return;
+  }
   PERIPH_WIRE.sendDataMasterWIRE(PMIC_REG07);
   // No D+/D– detection + Safety timer not slowed by 2X during input DPM or thermal regulation +
   // BAT fet disabled/enabled + charge and bat fault INT
   PERIPH_WIRE.sendDataMasterWIRE(0x0B | (disabled ? 0x20 : 0x00));
   PERIPH_WIRE.prepareCommandBitsWire(WIRE_MASTER_ACT_STOP);
+}
 
-  PERIPH_WIRE.disableWIRE();
+static inline bool is_battery_present() {
+
+  bool ret = PERIPH_WIRE.startTransmissionWIRE( PMIC_ADDRESS, WIRE_WRITE_FLAG );
+  if (!ret) {
+    return false;
+  }
+  PERIPH_WIRE.sendDataMasterWIRE(PMIC_REG08);
+  PERIPH_WIRE.prepareCommandBitsWire(WIRE_MASTER_ACT_STOP);
+
+  ret = PERIPH_WIRE.startTransmissionWIRE( PMIC_ADDRESS, WIRE_READ_FLAG );
+  if (!ret) {
+    return false;
+  }
+  uint8_t res = PERIPH_WIRE.readDataWIRE();
+  PERIPH_WIRE.prepareNackBitWIRE();
+  PERIPH_WIRE.prepareCommandBitsWire(WIRE_MASTER_ACT_STOP);
+  return ((res & 0b1000) != 0);
 }
 
 void initVariant() {
+  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);
+
   enable_battery_charging();
-  disable_battery_fet(false);
+  //disable_battery_fet(false);
+  delay(100);
+  bool batteryPresent = is_battery_present();
+  if (!batteryPresent) {
+    disable_battery_charging();
+  }
+
+  PERIPH_WIRE.disableWIRE();
 }
 #endif