MAX485 to TTL Conversion Guide

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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

SideSignals
TTL/MCU sideDI, RO, DE, RE, VCC, GND
RS-485 bus sideA, B
Datasheet-confirmed behavior

Table

PinFunction
DITTL input to the driver
ROTTL output from the receiver
DEDriver enable, high = transmit
REReceiver enable, low = receive
ANon-inverting RS-485 line
BInverting RS-485 line
VCC5 V ±5%
GNDGround
Typical MCU hookup

Table

MCU UARTMAX485CSA+
TXDI
RXRO
GPIODE and/or RE
5 VVCC
GNDGND
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
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Files

Pins

Symbol

Layout

3D View

Name
Pin #
Type
Part Type
Terminal Order
Terminal Type
~{RST}
1
Unspecified
Terminal
INPUT
A0
2
Unspecified
Terminal
INPUT
D0
3
Unspecified
Terminal
bidi
SCK/D5
4
Unspecified
Terminal
bidi
MISO/D6
5
Unspecified
Terminal
bidi
MOSI/D7
6
Unspecified
Terminal
bidi
CS/D8
7
Unspecified
Terminal
bidi
3V3
8
Unspecified
Terminal
powerOut
5V
9
Unspecified
Terminal
powerIn
GND
10
Unspecified
Terminal
powerIn
D4
11
Unspecified
Terminal
bidi
D3
12
Unspecified
Terminal
bidi
SDA/D2
13
Unspecified
Terminal
bidi
SCL/D1
14
Unspecified
Terminal
bidi
RX
15
Unspecified
Terminal
INPUT
TX
16
Unspecified
Terminal
output

WeMos_D1_mini