Another update on Scasagrande’s project, GPIBUSB Adapter rev4:
After working closely with a few individuals it was discovered that some of the pre-existing GPIB software (such as KE5FX’s tools) has some hardcoded serial port settings, one of which being the use of hardware flow control. After getting builds of the software tools with these disabled, some buffer problems were found using the default settings, under Windows, without the flow control. Running the software with WINE on Linux did not produce these issues. With some small tweaks to either the software or to Windows USB settings would fix the issue but that’s not very intuitive. A better long term solution would be to wire up the hardware flow control lines in the next hardware revision for use in a future firmware update.
That’s what I’ve done with the revision 4 PCB. In addition, I grounded a few unused digital lines on the micro to be able to, starting with rev4+, check what the hardware revision is in software. I also added two LEDs to the FT230X to allow it to signal on TX and RX.