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Fixes #1183 — T-Echo Lite incorrect battery voltage

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Battery (TechoBoard.h/cpp): Added PIN_VBAT_MEAS_EN (P0.31) — the T-Echo
Lite has a gated voltage divider that must be enabled before reading. Also
added pinMode(PIN_VBAT_READ, INPUT) before each ADC read to reclaim P0.02
from other peripherals. Pin definitions hardcoded from LilyGo's
t_echo_lite_config.h.

I2C (variant.h): Corrected SDA/SCL from P0.04/P0.02 to P1.04/P1.02 per
LilyGo's IIC_1_SDA/IIC_1_SCL. The old P0.02 mapping conflicted with the
battery ADC pin.

GPS (variant.h): Corrected all five GPS pin assignments to match LilyGo's
config — UART TX/RX, wake, PPS, and power enable were all scrambled.

SPI (variant.h): Fixed SPI_INTERFACES_COUNT from _PINNUM(0, 2) to (2).

Tested on T-Echo Lite Non-Shell (USB-C, no display). Battery readings match
Heltec V4 reference within 10mV.
This commit is contained in:
pelgraine
2026-04-10 14:25:51 +10:00
parent be780491ac
commit d516cd8a9e
3 changed files with 53 additions and 30 deletions
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19
variants/lilygo_techo_lite/TechoBoard.h
View File

@@ -4,14 +4,12 @@
#include <Arduino.h>
#include <helpers/NRF52Board.h>
// built-ins
#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)
// ============================================================
// T-Echo Lite battery pins — hardcoded from LilyGo t_echo_lite_config.h
// NOT using any defines from variant.h for battery measurement
// ============================================================
#define PIN_VBAT_READ _PINNUM(0, 2) // BATTERY_ADC_DATA
#define PIN_VBAT_MEAS_EN _PINNUM(0, 31) // BATTERY_MEASUREMENT_CONTROL
class TechoBoard : public NRF52BoardDCDC {
public:
@@ -20,10 +18,11 @@ public:
uint16_t getBattMilliVolts() override;
const char* getManufacturerName() const override {
return "LilyGo T-Echo";
return "LilyGo T-Echo Lite";
}
void powerOff() override {
digitalWrite(PIN_VBAT_MEAS_EN, LOW);
#ifdef LED_RED
digitalWrite(LED_RED, LOW);
#endif
@@ -41,4 +40,4 @@ public:
#endif
sd_power_system_off();
}
};
};