firmware/variants/m5stack_coreink/variant.h

// Primary I2C Bus includes PCF8563 RTC Module
#define I2C_SDA 21
#define I2C_SCL 22

// 7-07-2023 Or enable Secondary I2C Bus
//#define I2C_SDA1 32
//#define I2C_SCL1 33

#define HAS_GPS 1
#undef GPS_RX_PIN
#undef GPS_TX_PIN
// Use Secondary I2C Bus as GPS Serial
#define GPS_RX_PIN 33
#define GPS_TX_PIN 32

// Green LED
#define LED_INVERTED 0
#define LED_PIN 10

#include "pcf8563.h"
// PCF8563 RTC Module
#define PCF8563_RTC 0x51
#define HAS_RTC 1

// Wheel
//  Down 37
//  Push 38
//  Up 39
//  Top Physical Button 5

#define BUTTON_NEED_PULLUP
#define BUTTON_PIN 5

// BUZZER
#define PIN_BUZZER 2

#undef RF95_SCK
#undef RF95_MISO
#undef RF95_MOSI
#undef RF95_NSS
#define USE_RF95

#define RF95_SCK 18
#define RF95_MISO 34
#define RF95_MOSI 23
#define RF95_NSS 14
#define LORA_DIO0 25
#define LORA_RESET 26
#define LORA_DIO1 RADIOLIB_NC
#define LORA_DIO2 RADIOLIB_NC

#define USE_EINK
// https://docs.m5stack.com/en/core/coreink
// https://m5stack.oss-cn-shenzhen.aliyuncs.com/resource/docs/schematic/Core/coreink/coreink_sch.pdf
#define PIN_EINK_EN -1   // N/C
#define PIN_EINK_CS 9    // EPD_CS
#define PIN_EINK_BUSY 4  // EPD_BUSY
#define PIN_EINK_DC 15   // EPD_D/C
#define PIN_EINK_RES -1  // Connected but not needed
#define PIN_EINK_SCLK 18 // EPD_SCLK
#define PIN_EINK_MOSI 23 // EPD_MOSI