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Author Topic: JTAG interface?  (Read 164 times)

grmpf

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JTAG interface?
« on: August 24, 2019, 05:37:42 PM »
Does the Teres-I support JTAG hardware debugging?. I.e. is there a possibility to connect an adapter in order to attach it to some JTAG HW debugger (Segger, OpenOCD,..)?

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Jörg

grmpf

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Re: JTAG interface?
« Reply #1 on: August 27, 2019, 11:51:57 PM »
Ok, apparently there is no "sure, yesss!". I digged a little bit into the schematics and the device tree. Pins PB0..PB3 seem to be jtag0 MS,CK,DO,DI. What I can read from the schematics they are routed to the main board CON4 lines 16..13. Is CON4 connected to anything?

There is also a "JTAGSEL0" PIN on the Allwinner A64 which is connected to the power button board. What purpose is it for?

The jtag1 pins are used for the micro SD card. Those lines have some pullup resistors - does anybody know if these make the use for jtag impossible?

For the Teres-II mainboard that may come at some time in future I vote for a special JTAG breakout connector.

LubOlimex

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Re: JTAG interface?
« Reply #2 on: August 28, 2019, 03:39:39 PM »
The hardware connection would be the easy part....

I haven't seen someone succeed in the JTAG debugging of A64.
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grmpf

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Re: JTAG interface?
« Reply #3 on: August 28, 2019, 09:51:25 PM »
Too bad :( the A64 manual in fact does not tell too much about JTAG either.