I have a Pogoplug (the marvell sheevaplug without the debug/SDIO board). I have built a USB to serial cable using a Nokia CA-42 cable which connects to the serial tx, rx and gnd. I can connect to the serial console using PuTTY from Linux Mint 6 XFCE so I know that the cable is wired up correctly.
I have been unable to get openOCD working. I see that openOCD typically uses the FTDI 2232 chip but my cable uses a Prolific PL2303 chip with a pid/vid of 0x67b/0x2303. I am fairly new to Linux and have tried playing with modprobe and udev rules, I feel like I’m getting close but no luck so far.
My question: is it possible to to get openOCD working with the PL2303 chip?
OpenOCD uses a JTAG connection to debug a target. This is a very different type of serial interface from “standard” serial connections with tx, rx and gnd.
The FT2232 chip is often used for USB to serial communications, but OpenOCD uses a different mode called MPSSE. The PL2303 chip cannot do this.
No, the JTAG interface uses 4 signals called TDI, TDO, TMS and TCK and also signals to control the target reset lines. The normal rx and tx are used here but in a different mode and as you can see more signal pins are needed.
If you are deeply into DIY electronics it is possible to make a openocd compatible jtag interface from a ft2232 chip.
It is reasonably simple to build an interface from a FT2232 module