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Re: [avr-libc-dev] [bug #37772] wdt_enable() doesn't work for a list of
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From: |
Joerg Wunsch |
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Subject: |
Re: [avr-libc-dev] [bug #37772] wdt_enable() doesn't work for a list of chips |
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Date: |
Mon, 19 Nov 2012 10:33:15 +0100 |
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User-agent: |
Mutt/1.5.20 (2009-06-14) |
As Anton Voloshin wrote:
> My bad. LDI takes 1 cycle, and it's not even here. The reason is that OUT
> instruction enables interrupts here, and interrupt can occure before the
> second STS instruction.
On tiny/mega AVRs, re-enabling interrupts is always delayed by one
instruction, that is, the STS instruction right after the OUT is still
executed with interrupts disabled. This has been the way all the
time, and GCC relies on this in the function epilogue as well. (On
Xmega AVRs, this has been changed in hardware, so GCC emit a different
epilogue there. However, the Xmega watchdog handling is different
anyway.)
Curious, are you experiencing this on real hardware, or are you using
a simulator?
--
cheers, J"org .-.-. --... ...-- -.. . DL8DTL
http://www.sax.de/~joerg/ NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)