RS232Raw Emulation Information
This document describes the rs232-raw pluggable, which connects an
emulated RS232 port to a host serial port.
Overview
The rs232-raw RS232 pluggable forwards the RS232 traffic between an MSX
device (UART) and a real serial port of the host operating system. It is the
primary way to connect a real ESP32 (running the ESP32-UNAPI firmware) to
openMSX, for instance through the SM-X WiFi device.
The host serial port is selected with the rs232-raw-port setting (default
COM1 on Windows, /dev/ttyS0 on Linux).
Tested RS232 devices
The pluggable has been tested with the following RS232 devices:
- I8251 UART (e.g. the MSXRS232 device)
- SM-X UART (the SM-X WiFi device)
- MSXRS232 device
- SM-X WiFi device
Compatibility note
The RS232Raw pluggable adjusts the serial port parameters (baud rate, data bits, stop bits, parity) when the emulated UART issues a speed or mode change. Other RS232 devices not listed above might need to be adapted to propagate UART speed updates to the pluggable; otherwise the serial port may operate at the wrong speed or with incorrect framing parameters.
When in doubt, test with one of the verified devices first.
IMPORTANT
This might not be time accurate, i.e.: hardware flow control might not work as expected. Nowadays most of the serial ports are USB converters, and there is a latency, so changes might be advertised later than when they happened, same when you set a signal line. This emulation exists only to allow use of software and hardware for evaluation, it should not be assumed that if an application runs with this emulation it will run on real hardware, if using for development, always validate on the real hardware.