I've encountered a few dead ends trying to use the FT4232H chip (minimodule) (with D2XX driver from ftdi) to program a Cortex-M0 which only supports SWD . but I've managed to get it working using the so called "resistor hack" instead of an SWD<->JTAG adapter.
Even if this works there are still some speed issues (can't go over 1300kHz adapter speed) so I'm trying to use buffers instead of a resistor in order to have a more proper JTAG<->SWD interface and see if it changes anything. The documentation of openocd is still a little poor, so there are a few things that I couldn't find on the internet .My questions are the following :
Q1-> in my cfg file I use the ftdi configuration variables, some of which I don't understand fully.
---> The SWD signals one needs to configure are SWDIO_OE and SWD_EN. I can't figure out what SWD_EN (swd enable ??) stands for
---> Also the bitMask system is not described anywhere, I figured it out by "reversing" the cfg files already present in openocd and looking up the pinout of the resepective adapters of these files, but I can't be sure a 100% .So if someone knows where that information is or how to get it please share !!
Q2-> I'd like to use both of the FT4232H's JTAG channels at the same time. I'm able to run them one at a time but when I run both at once an error occurs. Does anyone have any info on this kind of behaviour ?
If you require any further information I'd be glad to answer. Thanks in advance.