JTAG connector for ARM7

Community PCB Design
1

Hi,

I use a JTAG programmer from Olimex, it works decently well, though it requires a huge connector on the PCB.

For now I have to opt the connector out whenever I design smaller boards. This is not ideal because I lose a big chunk of the debugging capabilities of the ARM7. I’ve been considering using a smaller connector, and build a different harness to interface with the JTAG programmer…

I’m sure this is somebody’s else issue too. How did you handle it?

Thanks!

2

You could just use a smaller connector. Or, have the standard connector on a sort of stub that can be cut off the PCB when it is no longer required. Another option is to use pogo pins in a fixture that contact pads on the underside of the PCB.

Leon

3

leon_heller:
You could just use a smaller connector. Or, have the standard connector on a sort of stub that can be cut off the PCB when it is no longer required. Another option is to use pogo pins in a fixture that contact pads on the underside of the PCB.

Leon

I’m definitely going to use a smaller connector. The pogo pins seems interesting. I just wish the jtag programmer came with less pins, most of them are grounds anyways!

4

They are needed for grounds on the cable to ensure signal integrity. Details are in the ARM JTAG specification.

Leon

5

There is a new standard for Cortex M debug connectors, which uses some 0.05 inch pitch connectors, and exploits SWD. However, they still have the normal pinout which would work for ARM7TDMI as well. You’ll have to make an adapter board.

http://infocenter.arm.com/help/index.js … 13634.html

I have also homebrewed a 20pin to 8pin (2mm pitch) adapter I used for awhile.