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Fixes #1183 — T-Echo Lite incorrect battery voltage + headless env support#2287

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pelgraine wants to merge 1 commit intomeshcore-dev:devfrom
pelgraine:fix/techo-lite-battery
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Fixes #1183 — T-Echo Lite incorrect battery voltage + headless env support#2287
pelgraine wants to merge 1 commit intomeshcore-dev:devfrom
pelgraine:fix/techo-lite-battery

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@pelgraine pelgraine commented Apr 10, 2026

The T-Echo Lite variant files were copied from the T-Echo without adapting to the Lite's different hardware. Three issues fixed, plus build environments added for the screenless Core variant.

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.

Headless builds (platformio.ini): Added LilyGo_T-Echo-Lite-Core base config and LilyGo_T-Echo-Lite-Core_repeater / LilyGo_T-Echo-Lite-Core_companion_radio_ble environments for the screenless T-Echo Lite variants — strips display-related flags, source files, and GxEPD2 dependency.

Tested on T-Echo Lite Base (screenless):
H747-01_01

Battery readings now match Heltec V4 comparison reference within 10mV - Heltec v4 read partially discharged battery as 3.51v, screenshots of T-Echo Lite readings below:

IMG_2110
IMG_2111
IMG_2112

@pelgraine pelgraine changed the title Fixes #1183 — T-Echo Lite incorrect battery voltage + headless (Core) support Fixes #1183 — T-Echo Lite incorrect battery voltage + headless env support Apr 10, 2026
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