Add MeshCore relay_radio firmware for Heltec T114

variants/lilygo_techo_lite/TechoBoard.cpp

@@ -0,0 +1,54 @@
+#include <Arduino.h>
+#include <Wire.h>
+
+#include "TechoBoard.h"
+
+#ifdef LILYGO_TECHO
+
+void TechoBoard::begin() {
+  NRF52Board::begin();
+
+  // Configure battery measurement control BEFORE Wire.begin()
+  // to ensure P0.02 is not claimed by another peripheral
+  pinMode(PIN_VBAT_MEAS_EN, OUTPUT);
+  digitalWrite(PIN_VBAT_MEAS_EN, LOW);
+  pinMode(PIN_VBAT_READ, INPUT);
+
+  Wire.begin();
+
+  pinMode(SX126X_POWER_EN, OUTPUT);
+  digitalWrite(SX126X_POWER_EN, HIGH);
+  delay(10);
+}
+
+uint16_t TechoBoard::getBattMilliVolts() {
+  // Use LilyGo's exact ADC configuration
+  analogReference(AR_INTERNAL_3_0);
+  analogReadResolution(12);
+
+  // Enable battery voltage divider (MOSFET gate on P0.31)
+  pinMode(PIN_VBAT_MEAS_EN, OUTPUT);
+  digitalWrite(PIN_VBAT_MEAS_EN, HIGH);
+
+  // Reclaim P0.02 for analog input (in case another peripheral touched it)
+  pinMode(PIN_VBAT_READ, INPUT);
+  delay(10);  // let divider + ADC settle
+
+  // Read and average (matching LilyGo's approach)
+  uint32_t sum = 0;
+  for (int i = 0; i < 8; i++) {
+    sum += analogRead(PIN_VBAT_READ);
+    delayMicroseconds(100);
+  }
+  uint16_t adc = sum / 8;
+
+  // Disable divider to save power
+  digitalWrite(PIN_VBAT_MEAS_EN, LOW);
+
+  // LilyGo's exact formula: adc * (3000.0 / 4096.0) * 2.0
+  // = adc * 0.73242188 * 2.0 = adc * 1.46484375
+  uint16_t millivolts = (uint16_t)((float)adc * (3000.0f / 4096.0f) * 2.0f);
+
+  return millivolts;
+}
+#endif