MAX485 RS-485 module with ESP32

Supply 5 V Bus GPIO

Pins and ESP32 wiring

Pin	Role	ESP32 pin	Notes
RO	Output (the part drives it)	D25	Receiver out, 5 V when powered from 5 V: use a divider before the ESP32 RX pin
RE	Input (the ESP32 drives it)	D26	Receiver enable, active LOW. Usually tied to DE and driven by one GPIO
DE	Input (the ESP32 drives it)	D27	Driver enable, HIGH to transmit
DI	Input (the ESP32 drives it)	D32	Driver in. Connect to an ESP32 TX pin (3.3 V is a valid HIGH)
VCC	Power	VIN	Needs 5 V: use VIN
B	Not wired to the ESP32	—	RS-485 line B. To the bus, never to the ESP32
A	Not wired to the ESP32	—	RS-485 line A. To the bus, never to the ESP32
GND	Ground	GND

Suggested wiring for the 30-pin ESP32 DevKit, avoiding flash, input-only and strapping pins. BoardPilot checks it for you as you wire.

This module is sold for 5 V. Its outputs may be 5 V: use a level shifter or a voltage divider on ESP32 inputs.

Maxim MAX481/MAX483/MAX485 datasheet, Supply 4.75 to 5.25 V; RO, RE, DE, DI, A, B pin functions; input HIGH threshold 2.0 V

Part data: CC BY 4.0, free to reuse with credit to BoardPilot.