PSA USB-C FTDI serial adapter and XMODEM issues

[Massimo]

In the past few days I was banging my head trying to make xmodem work between my PC with Tera Term and my Z80 SBC (Tom Szolyga’s) and no matter what it wasn't having it.

Well it turns out it was the specific adapter I was using: USB-C FTDI marked YP-05.

Another board which looks identical but uses mini-usb works just fine.

Mind you the terminal was working fine in any case, just xmodem was having issues with the USB-C one.

The caveat at least in my specific case is that prior to switching adapter I modified my board to actually use RTS/CTS and not CTS/DTR. In other words I cut the trace from the DTR pin on the header to SIO/2 pin 16 (DTRA) and wired it to SIO/2 pin 17 (RTSA) and also added a 100k pull down resistor to CTS.

Basically I copied what other SIO/2 board do but I don't know if it's strictly necessary and if xmodem would've worked with the stock configuration.

A couple of issues are still pending for me: when I power the board the serial adapter seems to freak out and it disconnects for a second which means I have to reset the board to get the prompt which renders moot the presence of the DS1233 power supervisor.

The other issue is that the same setup that works perfectly with Tera Term still doesn't work with minicom on Mac, but that seems to be something more specific also tied to drivers