I'm trying to get Zimodem to work with an ESP-12F NodeMCU board, a MAX3232 module and a BBC Micro, as described on this website: https://www.northdevonretroarchive.co.uk/getting-the-bbc-micro-online-via-wifi/

I've verified that my BBC Micro serial port, my serial cable and my MAX3232 module are working correctly by wiring the MAX3232's TX and RX together, the BBC then successfully receives characters it sends via the serial port.

It's my understanding that the ESP-12F should be identical to the ESP-12E except for having a more optimised antenna design, and also the 12F is available with a USB-C port instead of micro-USB which is important for me as all my chargers are USB-C now.

Trying it with the modified precompiled binary supplied on the North Devon page, I am able to see the initialisation message on the BBC Micro, but the NodeMCU does not seem to accept anything transmitted from the BBC Micro.

Attempting to compile it myself, while the Arduino IDE outputs what appears to be a valid compiled .bin file, if I attempt to flash this to the NodeMCU and hook it up to serial, I don't get any response out of it at all.

I managed to compile Zimodem 4.0.2 myself and upload it to the NodeMCU board, my mistake was I wasn't selecting the "Generic" board, but even so, it just stops after the initialisation message.

My PC is Windows 11, running Arduino IDE 2.3.2, I've tried compiling Zimodem both with the latest version 3.1.2 board package and I also tried it with the older 2.7.4 version recommended by the Zimodem README.

Can anyone suggest what I might be doing wrong or what additional steps I might need to take to get this to work?