MAX485 to TTL Conversion Guide

Thought for 28 sec

MAX485CSA+ is not an RS-485-to-TTL converter in only one direction - it is a TTL/CMOS UART to RS-485 transceiver.

What it does

Table

Side	Signals
TTL/MCU side	`DI`, `RO`, `DE`, `RE`, `VCC`, `GND`
RS-485 bus side	`A`, `B`

Datasheet-confirmed behavior

Table

Pin	Function
`DI`	TTL input to the driver
`RO`	TTL output from the receiver
`DE`	Driver enable, high = transmit
`RE`	Receiver enable, low = receive
`A`	Non-inverting RS-485 line
`B`	Inverting RS-485 line
`VCC`	5 V ±5%
`GND`	Ground

Typical MCU hookup

Table

MCU UART	MAX485CSA+
TX	`DI`
RX	`RO`
GPIO	`DE` and/or `RE`
5 V	`VCC`
GND	`GND`

Important note

The datasheet says MAX485CSA+ operates from a single 5 V supply, with logic thresholds:

VIL = 0.8 V
VIH = 2.0 V

So a 3.3 V MCU can usually drive its logic inputs, but the chip itself is still a 5 V device.

If you want, I can also give you:

a MAX485 to Arduino/ESP32 wiring table
a half-duplex DE/RE control example
or help find a 3.3 V RS-485 transceiver instead.

ESP32 wiring table

Add termination parts

3.3V transceiver option

DE RE control

SCL/D1

3V3

SDA/D2

~{RST}

Reviews

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