Software bricks SAMA5D2 Xplained Ultra board? How to unbrick it?

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Crank
Posts: 3
Joined: Fri Jun 29, 2018 5:50 pm

Software bricks SAMA5D2 Xplained Ultra board? How to unbrick it?

Sun Jul 29, 2018 3:05 pm

Hi,

I'm in a really big hurry with this one so quick replies are appreciated. Here's the problem I'm having currently:

I'm writing bare metal firmware for SAMA5D2 and when I added FPU register saving/restoring to stack in the task switching IRQ routine, the board hung up. Nothing new there so far as it seems like a simple bug to fix. BUT when I powered down everything and plugged the power back in, my IDE+programming device doesn't recognise the SAMA5D2 anymore? I just get an error "Failed to set halt mode debug - is DBGEN enabled?".

What's going on? How can couple of assember lines of code brick the whole unit?

I tried switching to a bare new SAMA5D2 board, and disabled the offensive assembler lines (and their placeholders in the task's initialized stack) and everything worked as it should. When I enabled the assembler lines of code, the bare new SAMA5D2 board got bricked too! Now I have no dev-boards left which work.

I'm not uploading anything to the onboard FLASH. The firmware is always uploaded and run in the SDRAM. Nothing uses/tampers with the FLASH.

I'm using JTAG to program the device.

How do I get the boards working again?
blue_z
Location: USA
Posts: 1745
Joined: Thu Apr 19, 2007 10:15 pm

Re: Software bricks SAMA5D2 Xplained Ultra board? How to unbrick it?

Mon Jul 30, 2018 11:52 pm

Crank wrote:BUT when I powered down everything and plugged the power back in, my IDE+programming device doesn't recognise the SAMA5D2 anymore? I just get an error "Failed to set halt mode debug - is DBGEN enabled?".
You're not clear as to what this "programming device" is.
Is this "JTAG" a SAM-ICE, J-Link or the EDBG?
That message seems to be related to this "JTAG" rather than something that the SAMA5 SoC outputs.
Have you simplified the board connections, i.e. boot the bare board without this "JTAG" and any batteries, and monitor the serial DBGU port?

Crank wrote:How can couple of assember lines of code brick the whole unit?
You're not separating your assumptions from an accurate description of the situation.
You have only mentioned that the "JTAG" is nonresponsive and no other symptoms.

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