Version francophone.

Build a USB to Serial cable to communicate with the Playstation

This cable connects a PSX to a computer. If you combine this with a cart flashed with unirom, you can interract with the PSX from your computer, upload executables, access the console's memory...

What you can use :

• An FTDI FT232RL module OR
• An Arduino Uno that supports 3.3V serial OR
• A Raspberry Pi 0,1,2,3,4 OR
• A Raspberry Pi Pico OR
• A CP2102 or CP2104

If you have these stuff lying around, this can help :

• A PSX SCPH-1040 serial cable, or half a cable
• A dead PSX motherboard that has a serial port, or just the SIO socket
• Dupont wires

Connection

You only need 3 wires from the PSX : Tx, Rx and Gnd.

PSX pins | FTDI pins
2        |     GND   
8        |     TX 
5        |     RX 

Which controller can be used

FTDI FT232RL

Connect PSX SIO pins 2, 5, 8 to the FTDI's Tx, Rx and Gnd. Done.

3.3V Arduino Uno

Some arduino unos have a jumper to use 3.3V instead of 5V levels. You can use such a board with an addintional resistor, like so :

Sources : http://www.psxdev.net/forum/viewtopic.php?f=47&t=760&p=19081

Raspberry Pi

Either over your local network or via a direct lan cable setup, you can use a rpi if you have one lying around.

Plug the PSX's serial output Rx/TX/Gnd to the GPIO14/pin 8 (Tx), GPIO15/pin 10 (Rx) and pin 6 (Gnd).

See here : http://wiki.arthus.net/?psxdev-rpi_serial_over_network

Raspberry Pi Pico

The new controller by Rpi foundation can be used with the Pico-uart-bridge firmware :
https://github.com/Noltari/pico-uart-bridge/releases

Use GPO 0/Pin 1 as Tx, GPO 1/Pin 2 as Rx and GPO 3/Pin 3 as Gnd :

CP2102 / CP2104

The CP2102 and CP2104 are reported to work at least in /slow mode (115200 bauds).

Others :

• CH341 is reported to work in /slow mode (115200 bauds)

From the PSX to the controller

Method #1 : Half SCPH-1040 cable

Hack the cable, connect things and voila :

Sources : http://www.psxdev.net/forum/viewtopic.php?f=62&t=349#p2592
http://www.psxdev.net/forum/viewtopic.php?t=497#p3556

Method #2 : Salvaged PSX serial port + full SCPH-1040 cable

Use a salvaged PSX SIO port from a dead motherboard, and use your precious serial cable without destroying anything :

Source : http://www.psxdev.net/forum/viewtopic.php?t=744&sid=ff1cc884ceaaa4267404e61e81130320#p6524

Method #3 : Dead or spare PSX motherboard + full SCPH-1040 cable

Same as above except you don't even have to hack the SIO port off the motherboard, just solder your wires directly underneath the SIO port.

Sources : https://thp.io/2020/psxserial.html

Notes & Sources

Port série pinout :
https://www.problemkaputt.de/psx-spx.htm#pinouts

Méthode 1 :
http://www.psxdev.net/forum/viewtopic.php?f=62&t=349#p2592
http://www.psxdev.net/forum/viewtopic.php?t=497#p3556

Méthode 2 :
http://www.psxdev.net/forum/viewtopic.php?t=744&sid=ff1cc884ceaaa4267404e61e81130320#p6524

Méthode 3 :
https://thp.io/2020/psxserial.html
Méthode 4 : http://www.psxdev.net/forum/viewtopic.php?f=47&t=760&p=19081