July 23, 2021, 10:55:43 pm

JTAG header backwards?

Started by ninevoltz, February 28, 2020, 09:29:43 pm

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February 28, 2020, 09:29:43 pm Last Edit: February 28, 2020, 09:37:52 pm by ninevoltz Reason: added image
All of the Olimex diagrams of the 20-pin ARM JTAG header are backwards when compared to the standard ARM connector. Am I correct, or am I missing something?


Depends if you mean the one on the board or the one on the tool.

I've used multiple JTAG tools (not just Olimex) with multiple Olimex boards and they all worked so I think Olimex have it right.



March 02, 2020, 11:30:05 am #2 Last Edit: March 02, 2020, 02:29:33 pm by LubOlimex
The connector is fine, the information is improper since the image shows the schematic and the PCB pads (as seen at the bottom "ML20PADS") and it should show either the connector that is led out of the plastic box or the cable. The way it is now - it is not user-friendly and perplexing. Thanks for the notice I will make sure to fix it.
Technical support and documentation manager at Olimex


Thanks for clarifying. I've got a ULINK2 and an Olimex ARM-USB-OCD on the way. I had to design an adapter PCB for a project I'm working on and was hoping that my pinout wasn't going to be backwards. Sounds like I should be ok. Thanks!


March 02, 2020, 03:37:42 pm #4 Last Edit: March 02, 2020, 03:40:13 pm by LubOlimex
Now changed it to this: https://www.olimex.com/Products/ARM/JTAG/_resources/openocd-jtag-layout.png

Since I just overwrote the original image with the same name, now your original post looks funny :)
Technical support and documentation manager at Olimex