meshtastic-firmware/variants/tlora_v2_1_16/variant.h

#undef GPS_RX_PIN
#undef GPS_TX_PIN
#define GPS_RX_PIN 15 // per @der_bear on the forum, 36 is incorrect for this board type and 15 is a better pick
#define GPS_TX_PIN 13

#define EXT_NOTIFY_OUT 2 // Default pin to use for Ext Notify Module.

#define BATTERY_PIN 35 // A battery voltage measurement pin, voltage divider connected here to measure battery voltage
// ratio of voltage divider = 2.0 (R42=100k, R43=100k)
#define ADC_MULTIPLIER 2.11 // 2.0 + 10% for correction of display undervoltage.

#define I2C_SDA 21 // I2C pins for this board
#define I2C_SCL 22

#define RESET_OLED 16 // If defined, this pin will be used to reset the display controller

#define VEXT_ENABLE 21 // active low, powers the oled display and the lora antenna boost
#define LED_PIN 25     // If defined we will blink this LED
#define BUTTON_PIN 12  // If defined, this will be used for user button presses,

#define BUTTON_NEED_PULLUP

#define USE_RF95
#define LORA_DIO0 26 // a No connect on the SX1262 module
#define LORA_RESET 14
#define LORA_DIO1 35 // Not really used
#define LORA_DIO2 34 // Not really used