November 21, 2016

JTAG

I have been meaning to learn about JTAG for a long time. My first exposure was via the 4 wire SWD interface on some ARM devices and the ST-LINK V2 that connects to them. This worked amazingly well with OpenOCD and Gdb.

Later I bought a Segger J-Link (on Ebay for about $12) which I have yet to use.

Segger J-link

These things cost $400 full price (if you intend to use it in a commercial way). The same unit for educational use sells for $70. Segger calls the 10 pin cable the "9 pin Cortex M adapter" and sells the board and cable for $70. It is 9 pin because pin 7 in a no-connect.

Note that with ARM you may have a choice of using JTAG or the simpler SWD interface.

JTAG and the BBB

You need to solder this thing on the back of the board first (20 pin connector)

JTAG and the Intel Galileo

Although the Galileo is an x86 system, it seems to use the 10 pin (aka 2x5) connector and pinout the same as the ARM. This is nice.
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Tom's Computer Info / tom@mmto.org