ColdFire/68K Microcontrollers and ProcessorsのトピックRe: RAM status during Watch dog timer

RAM status during Watch dog timer

MFC52259 — Fri, 17 Jul 2009 19:36:03 GMT

Hello,

I am using Cold fire MCF52259 in our project.

I wanted to know the status of variables declared in RAM

during the Watch dog timer reset.

Will the variable restore its value on next power ON?

Re: RAM status during Watch dog timer

admin — Sat, 18 Jul 2009 02:29:55 GMT

Based on my understanding of how CPU and RAM work, I can tell you that RAM contents will be preserved during watchdog reset. Of course, you'll have to make sure that startup code doesn't overwrite the variables you want to preserve.

Message Edited by scifi on 2009-07-17 08:30 PM

Re: RAM status during Watch dog timer

mjbcswitzerland — Sat, 18 Jul 2009 03:03:09 GMT

Regards

Mark

Re: RAM status during Watch dog timer

admin — Mon, 20 Jul 2009 16:47:16 GMT

mjbcswitzerland gave link to excellent explanation for SRAM.

But, content of DRAM isn't guaranteed to be preserved due to suspending of the refresh.

Note, that the start-up code regularly include some memory test, which overwrites the SRAM or DRAM content.

Re: RAM status during Watch dog timer

AloysiusJegan — Mon, 20 Jul 2009 19:18:12 GMT

Yevgenit,

Is it not possible to stop memory test during soft reset?

Jegan

Re: RAM status during Watch dog timer

admin — Mon, 20 Jul 2009 19:50:42 GMT

I believe, any good start-up code has a few defines, which customize the behavior, including enable/disable memory test.

See the source code of your system start-up module. It's possible, that on-chip SRAM isn't tested at all.

Re: RAM status during Watch dog timer

AloysiusJegan — Mon, 20 Jul 2009 20:11:18 GMT

Yevgenit,

Thanks for your input.

Jegan