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Michal Demin posted a tutorial for the OpenOCD JTAG debugging support he added to the Bus Pirate.
Some time ago, I have added support to OpenOCD to be able to use Buspirate as JTAG interface. This how-to will show you, how to setup all the things necessary.
Things you will need:
– Computer with OpenOCD installed
– target with JTAG
– luck 🙂
robots, a new contributor to the Bus Pirate OpenOCD support effort, has taken charge and produced the first working toolchain. A patch for OpenOCD 0.3.0 that adds Bus Pirate support is here. The latest compatible OpenOCD firmware for the Bus Pirate is here, bootloader v4 required.
JTAG programming speed is a paltry 1.4kb/s, about a tenth the speed of a Wiggler. Due to the Bus Pirate’s slow serial port connection, there’s not a lot of room for improvement. We’re going to look at increasing the serial port speed and using interrupt-based data transfers to increase the speed.
We’re looking for additional testers and contributors, please let us know if it works for you.
Firmware is only half of the equation though, OpenOCD doesn’t yet support the USBPROG protocol over a (virtual) serial port like the Bus Pirate uses. There are about 8 instances of USB read and writes in the USBPROG OpenOCD patch than need to be changed to use a serial port, plus some serial port initialization functions. Any help and feedback is always appreciated, feel free to use the Bus Pirate OpenOCD support forum.
The current plan is to port the excellent work done by the USBPROG project to the Bus Pirate. Here are some tentative goals:
- Port the AVR/USB-based microcontroller code from USBPROG to the Bus Pirate. Modify the code to work through the PIC serial port.
- Add a Bus Pirate device to OpenOCD based on the existing USBPROG source code. Modify the code to write and read through a serial port.
- Add message header, checksum to the existing USBPROG protocol.
JTAG debugging support via OpenOCD is an exciting new feature. We hope to have a firmware for developers and testers in the next few days. Any help and feedback is always appreciated, feel free to use the Bus Pirate OpenOCD support forum.