Merge pull request #135 from recrof/dev

LilyGo T-ECHO: report correct battery voltage

src/helpers/nrf52/TechoBoard.cpp

@@ -22,11 +22,18 @@ void TechoBoard::begin() {
   // for future use, sub-classes SHOULD call this from their begin()
   startup_reason = BD_STARTUP_NORMAL;
 
-  pinMode(PIN_VBAT_READ, INPUT);
-
-#if defined(PIN_BOARD_SDA) && defined(PIN_BOARD_SCL)
-  Wire.setPins(PIN_BOARD_SDA, PIN_BOARD_SCL)
-#endif
+  delay(200);
+  pinMode(PIN_PWR_EN, OUTPUT);
+  digitalWrite(PIN_PWR_EN, HIGH);
+  pinMode(PIN_BUTTON1, INPUT_PULLUP);
+  pinMode(PIN_BUTTON2, INPUT_PULLUP);
+  pinMode(LED_RED, OUTPUT);
+  pinMode(LED_GREEN, OUTPUT);
+  pinMode(LED_BLUE, OUTPUT);
+  delay(200);
+
+  pinMode(PIN_TXCO, OUTPUT);
+  digitalWrite(PIN_TXCO, HIGH);
 
   Wire.begin();
 
@@ -35,6 +42,20 @@ void TechoBoard::begin() {
   delay(10);   // give sx1262 some time to power up
 }
 
+uint16_t TechoBoard::getBattMilliVolts() {
+  int adcvalue = 0;
+
+  analogReference(AR_INTERNAL_3_0);
+  analogReadResolution(12);
+  delay(10);
+
+  // ADC range is 0..3000mV and resolution is 12-bit (0..4095)
+  adcvalue = analogRead(PIN_VBAT_READ);
+  // Convert the raw value to compensated mv, taking the resistor-
+  // divider into account (providing the actual LIPO voltage)
+  return (uint16_t)((float)adcvalue * REAL_VBAT_MV_PER_LSB);
+}
+
 bool TechoBoard::startOTAUpdate(const char* id, char reply[]) {
   // Config the peripheral connection with maximum bandwidth
   // more SRAM required by SoftDevice

src/helpers/nrf52/TechoBoard.h

@@ -17,28 +17,26 @@
 #define SX126X_DIO3_TCXO_VOLTAGE   1.8
 
 // built-ins
-#define  PIN_VBAT_READ    4
-#define  ADC_MULTIPLIER   (2.0)
+#define VBAT_MV_PER_LSB   (0.73242188F)   // 3.0V ADC range and 12-bit ADC resolution = 3000mV/4096
+
+#define VBAT_DIVIDER      (0.5F)          // 150K + 150K voltage divider on VBAT
+#define VBAT_DIVIDER_COMP (2.0F)          // Compensation factor for the VBAT divider
+
+#define PIN_VBAT_READ     (4)
+#define REAL_VBAT_MV_PER_LSB (VBAT_DIVIDER_COMP * VBAT_MV_PER_LSB)
 
 class TechoBoard : public mesh::MainBoard {
 protected:
   uint8_t startup_reason;
 
 public:
-  void begin();
-  uint8_t getStartupReason() const override { return startup_reason; }
-
-  #define BATTERY_SAMPLES 8
 
-  uint16_t getBattMilliVolts() override {
-    analogReadResolution(12);
-    uint32_t raw = 0;
-    for (int i = 0; i < BATTERY_SAMPLES; i++) {
-      raw += analogRead(PIN_VBAT_READ);
-    }
-    raw = raw / BATTERY_SAMPLES;
+  void begin();
+  uint16_t getBattMilliVolts() override;
+  bool startOTAUpdate(const char* id, char reply[]) override;
 
-    return (ADC_MULTIPLIER * raw) / 4096;
+  uint8_t getStartupReason() const override {
+    return startup_reason;
   }
 
   const char* getManufacturerName() const override {
@@ -48,6 +46,4 @@ public:
   void reboot() override {
     NVIC_SystemReset();
   }
-
-  bool startOTAUpdate(const char* id, char reply[]) override;
 };

variants/techo/variant.h

@@ -14,12 +14,12 @@
 #define USE_LFXO    // 32.768 kHz crystal oscillator
 #define VARIANT_MCK (64000000ul)
 
-#define WIRE_INTERFACES_COUNT 	(1)
-
+#define WIRE_INTERFACES_COUNT   (1)
+#define PIN_TXCO                (21)
 ////////////////////////////////////////////////////////////////////////////////
 // Power
 
-#define PIN_PWR_EN              (6)
+#define PIN_PWR_EN              (12)
 
 #define BATTERY_PIN             (4)
 #define ADC_MULTIPLIER          (4.90F)
@@ -62,11 +62,11 @@
 ////////////////////////////////////////////////////////////////////////////////
 // Builtin LEDs
 
-#define LED_RED                 (13)
+#define LED_RED                 (34)
+#define LED_GREEN               (33)
 #define LED_BLUE                (14)
-#define LED_GREEN               (15)
 
-#define LED_BUILTIN             (15)
+#define LED_BUILTIN             LED_GREEN
 #define PIN_LED                 LED_BUILTIN
 #define LED_PIN                 LED_BUILTIN
 #define LED_STATE_ON            LOW
@@ -80,7 +80,7 @@
 #define PIN_BUTTON1             (42)
 #define BUTTON_PIN              PIN_BUTTON1
 
-#define PIN_BUTTON2             (18)
+#define PIN_BUTTON2             (11)
 #define BUTTON_PIN2             PIN_BUTTON2
 
 #define EXTERNAL_FLASH_DEVICES MX25R1635F