Quelltext der Seite WSAL21648 – RS485 RS232 HAT/en

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'''Documentation notice:''' This technical documentation was independently rewritten from an archived supplier source. Check technical details and commands against the product version and manufacturer documentation before use.

== Summary ==
The Waveshare RS485 RS232 HAT is an isolated expansion module for the 40-pin GPIO interface of Raspberry Pi boards. It uses a multi-chip combination of SC16IS752, SP3485 and SP3232 to enable both RS485 and RS232 communication via SPI (up to 921600 baud). The module features built-in power isolation, ADI magnetic coupling, TVS, fuse and protection diodes, as well as indicators for supply voltage and serial communication status.

== Related products at JW Tech ==
* [https://shop.jw-tech.eu/p/WSAL21648 WSAL21648 – Isolated RS485 RS232 Expansion HAT for Raspberry Pi, SPI Control]

== Technical overview ==
* Based on the 40-pin GPIO interface, suitable for the Raspberry Pi series.
* Uses SC16IS752 (UART expansion chip), SP3485 (RS485 transceiver) and SP3232 (RS232 transceiver) in a multi-chip combination.
* Communication rate: 300 to 921600 baud.
* Operating voltage: 3.3 V / 5 V.
* Dimensions: 65 mm × 56.5 mm; via diameter: 3.0 mm.
* RS485 supports manual or automatic transmit/receive switching, configurable via DIP switch.
* Built-in TVS (transient voltage suppression), resettable fuse and protection diodes guard against overvoltage, overcurrent and static discharge.
* Onboard indicators for power supply and serial communication simplify status checks.
* Leads out the SPI control interface for easy access from main control boards such as Arduino.
* Provides complete supporting information manuals (C and Python sample programs and user manuals).

'''Commands and examples – verify before use:''' 
<syntaxhighlight lang="text">
sudo nano /boot/config.txt
dtoverlay=sc16is752-spi1,int_pin=24
sudo reboot
ls /dev
wget http://www.airspayce.com/mikem/bcm2835/bcm2835-1.71.tar.gz
tar zxvf bcm2835-1.71.tar.gz
cd bcm2835-1.71/
sudo ./configure && sudo make && sudo make check && sudo make install
sudo apt-get install wiringpi
wget https://project-downloads.drogon.net/wiringpi-latest.deb
sudo dpkg -i wiringpi-latest.deb
gpio -v
sudo apt-get update
sudo apt-get install python-pip
sudo pip install RPi.GPIO
sudo apt-get install python-serial
sudo apt-get install python3-pip
sudo pip3 install RPi.GPIO
sudo apt-get install python3-serial
sudo apt-get install p7zip-full
</syntaxhighlight>

== Notes and version constraints ==
* The exact pinout of the IRQ pin depends on the actual soldering method; int_pin must be adjusted accordingly.
* For Ubuntu Bullseye systems, 'apt-get' must be replaced with 'apt'; only Python3 is supported and wiringPi is absent.
* On the Raspberry Pi system dated 2020-05-27, gpiochip3 did not become gpiochip2.
* For the C and Python demos, an additional RS485-to-serial-port module connected to channel 1 is required to see the effect; test.py requires channel 1 and channel 2 to be connected.
* If RS485 communication is abnormal: Check whether A and B of the 485 lines match the controlled 485 devices, first use a USB-to-RS485 device to communicate with the module to ensure the Raspberry Pi settings are correct, and check the parity bit settings of the serial communication parameters.
* The config.txt file cannot be changed directly on the Raspberry Pi; it must be edited via a card reader on a computer.

== Source and revision record ==
* [https://www.waveshare.com/wiki/RS485_RS232_HAT RS485 RS232 HAT - Waveshare Wiki]
* Source revision: 84536
* Captured: 2026-09-03T03:09:25+00:00
* SHA-256: <code>2b46fb951a3ba97f75cc014bdb039837a033776effd9335470f8bee0e309c559</code>