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Subject: Re: jethead71: firmware/target/coldfire system-coldfire.c,1.2,1.3

Re: jethead71: firmware/target/coldfire system-coldfire.c,1.2,1.3

From: Jens Arnold <arnold-j_at_t-online.de>
Date: Sun, 05 Nov 2006 01:51:24 +0100

On 03.11.2006, Linus Nielsen Feltzing wrote:

> cvs_at_labb.contactor.se wrote:
>> More tweak to ColdFire default exception handler. iRiver
>> reboots on power press but x5 just shuts down. Haven't yet
>> thought much about why or how to make it reboot on x5 if it's
>> possible.

> The X5 shuts down because the KEEP_ACT signal goes inactive
> when the port pins are tri-stated at reset. It's the same with
> H300.

The reset from the UIE handler _does_ work on H300 without
cutting power, I just checked it on mine.

The UIE handler uses a special way to generate a reset: by
starting the coldfire watchdog timer but not servicing it.
This special trick is necessary because system_reboot() doesn't
work correctly when the UIE is entered from the debug interrupt
(i.e. the memory guard feature). This is because the debug
interrupt switches the coldfire into emulator mode, and there
are only 2 ways to get out of emulator mode: by issuing an rte
instruction, or by performing a reset.

Regards, Jens
Received on 2006-11-05


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