Added power and battery management

Power.h

@@ -0,0 +1,106 @@
+#if BOARD_MODEL == BOARD_TBEAM
+  #include <axp20x.h>
+  AXP20X_Class PMU;
+
+  void disablePeripherals() {
+    PMU.setPowerOutPut(AXP192_DCDC1, AXP202_OFF);
+    PMU.setPowerOutPut(AXP192_LDO2, AXP202_OFF);
+    PMU.setPowerOutPut(AXP192_LDO3, AXP202_OFF);
+  }
+#elif BOARD_MODEL == BOARD_RNODE_NG_21 || BOARD_MODEL == BOARD_LORA32_V2_1
+  #define BAT_V_MIN  3.4
+  #define BAT_V_MAX  4.2
+  #define BAT_V_CHG  4.345
+  #define BAT_V_CHGD 4.31
+  const uint8_t pin_vbat = 35;
+#endif
+
+uint32_t last_pmu_update = 0;
+uint8_t pmu_target_pps = 1;
+int pmu_update_interval = 1000/pmu_target_pps;
+
+void measure_battery() {
+  #if BOARD_MODEL == BOARD_RNODE_NG_21 || BOARD_MODEL == BOARD_LORA32_V2_1
+    battery_voltage = (float)(analogRead(pin_vbat)) / 4095*2*3.3*1.1;
+    battery_percent = ((battery_voltage-BAT_V_MIN) / (BAT_V_MAX-BAT_V_MIN))*100.0;
+    
+    if (battery_percent > 100.0) battery_percent = 100.0;
+
+    if (battery_voltage > BAT_V_CHG) {
+      battery_state = BATTERY_STATE_CHARGING;
+      // Serial.printf("Battery charging. Voltage=%.2fv, percentage: %.2f%\n", battery_voltage, battery_percent);
+    } else if (battery_voltage > BAT_V_CHGD) {
+      battery_state = BATTERY_STATE_CHARGED;
+      // Serial.printf("Battery charged. Voltage=%.2fv, percentage: %.2f%\n", battery_voltage, battery_percent);
+    } else {
+      battery_state = BATTERY_STATE_DISCHARGING;
+      // Serial.printf("Battery discharging. Voltage=%.2fv, percentage: %.2f%\n", battery_voltage, battery_percent);
+    }
+
+  #elif BOARD_MODEL == BOARD_TBEAM
+    battery_voltage = 0.0;
+    battery_percent = 0.0;
+  #endif
+}
+
+void update_pmu() {
+  if (millis()-last_pmu_update >= pmu_update_interval) {
+    measure_battery();
+    last_pmu_update = millis();
+  }
+}
+
+bool init_pmu() {
+  #if BOARD_MODEL == BOARD_RNODE_NG_21 || BOARD_MODEL == BOARD_LORA32_V2_1
+    pinMode(pin_vbat, INPUT);
+    return true;
+  #elif BOARD_MODEL == BOARD_TBEAM
+    Wire.begin(I2C_SDA, I2C_SCL);
+    if (PMU.begin(Wire, AXP192_SLAVE_ADDRESS) == AXP_FAIL) return false;
+
+    // Configure charging indicator
+    PMU.setChgLEDMode(AXP20X_LED_OFF);
+
+    // Turn off unused power sources to save power
+    PMU.setPowerOutPut(AXP192_DCDC1, AXP202_OFF);
+    PMU.setPowerOutPut(AXP192_DCDC2, AXP202_OFF);
+    PMU.setPowerOutPut(AXP192_LDO2, AXP202_OFF);
+    PMU.setPowerOutPut(AXP192_LDO3, AXP202_OFF);
+    PMU.setPowerOutPut(AXP192_EXTEN, AXP202_OFF);
+
+    // Set the power of LoRa and GPS module to 3.3V
+    PMU.setLDO2Voltage(3300);   //LoRa VDD
+    PMU.setLDO3Voltage(3300);   //GPS  VDD
+    PMU.setDCDC1Voltage(3300);  //3.3V Pin next to 21 and 22 is controlled by DCDC1
+
+    PMU.setPowerOutPut(AXP192_DCDC1, AXP202_ON);
+
+    // Turn on SX1276
+    PMU.setPowerOutPut(AXP192_LDO2, AXP202_ON);
+
+    // Turn off GPS
+    PMU.setPowerOutPut(AXP192_LDO3, AXP202_OFF);
+
+    pinMode(PMU_IRQ, INPUT_PULLUP);
+    attachInterrupt(PMU_IRQ, [] {
+      // pmu_irq = true;
+    }, FALLING);
+
+    PMU.adc1Enable(AXP202_VBUS_VOL_ADC1 |
+                   AXP202_VBUS_CUR_ADC1 |
+                   AXP202_BATT_CUR_ADC1 |
+                   AXP202_BATT_VOL_ADC1,
+                   AXP202_ON);
+
+    PMU.enableIRQ(AXP202_VBUS_REMOVED_IRQ |
+                  AXP202_VBUS_CONNECT_IRQ |
+                  AXP202_BATT_REMOVED_IRQ |
+                  AXP202_BATT_CONNECT_IRQ,
+                  AXP202_ON);
+    PMU.clearIRQ();
+
+    return true; 
+  #else
+    return false;
+  #endif
+}