I have a detailed question about one of the OpenOCD commands in the “sifive-freedom-e300-hifive1.cfg”…
The ftdi_layout_init command includes 0x0008 and 0x001b as parameters. I don’t get how this configures the FT2232HL part to place port A into MPSSE mode. The OpenOCD documentation says that “ftdi_layout_init command”:
“Specifies the initial values of the FTDI GPIO data and direction registers. Each value is a 16-bit number corresponding to the concatenation of the high and low FTDI GPIO registers. The values should be selected based on the schematics of the adapter, such that all signals are set to safe levels with minimal impact on the target system. Avoid floating inputs, conflicting outputs and initially asserted reset signals.”
When I look through the FT2232H documentation and FTDI Application Notes, there is no mention of “data” or “direction” registers. Also the hifive-a01-schematics aren’t wired up to use the ADBUS4 or BDBUS3 port bits which would seem like what the extra bits in 0x001b and 0x0008 respectively would be used for.
I’m pretty certain I’m not looking in the right documentation to understand this.
Could someone with more domain knowledge please just point me in the right direction so I don’t waste a lot more time on this?
Thanks in advance.