8-bit MicrocontrollersのトピックSTOP2 mode wakeup, restore register content issue

STOP2 mode wakeup, restore register content issue

marmotte — Fri, 13 Nov 2015 15:39:41 GMT

Hi,

I use a MC9S08QE16CLC mcu, CW10.6 and processor expert.

My goal is to make S08 to enter STOP2 mode and exit by asserting IRQ pin ==> No problem to do that it works well

Before entering STOP2, I save to RAM the content of some registers I'd like to restore when MCU wakes up. This is where I get the issue.

in start08.c: The _Startup(void) is called after reset (and also wakeup) which itself call the Init(); function which ZERO-OUT all RAM content ==> the register content copy I stored in RAM before entering STOP2 is also initialized/erased.

Is there a way to prevent my stored datas to be initialized by Init() function in the StartUp code?

How can I proceed?

Thanks and Sorry for my poor english.

Re: STOP2 mode wakeup, restore register content issue

kef2 — Mon, 16 Nov 2015 10:43:33 GMT

In PRM file you can replace READ_WRITE with NO_INIT. This will prevent initialization variables, which are placed in specified memory segments.

You can also split RAM segment into two segments, READ_WRITE part and NO_INIT part like below.

In PRM SEGMENTS:

/*RAM = READ_WRITE 0x0100 TO 0x047F;*/

RAM = READ_WRITE 0x0100 TO 0x037F;

NIRAM = NO_INIT 0x0380 TO 0x047F;

in PRM PLACEMENT add

NOINITRAM INTO NIRAM;

In C code:

#pragma DATA_SEG NOINITRAM

// data in NOINITRAM won't be initialized by startup code

int v1, v2, v3;

#pragma DATA_SEG DEFAULT

Re: STOP2 mode wakeup, restore register content issue

marmotte — Thu, 19 Nov 2015 09:15:45 GMT

Thanks a lot for your help, it now works as expected.