MCF51QE128 - Low Power Modes - stop4, stop3

Parker — Fri, 09 Nov 2007 00:13:58 GMT

Hi,

I am pretty new to the QE128. Right now I am wondering, if there are some code examples somewhere in the net. I only found some examples in this document here (http://www.freescale.com/files/microcontrollers/doc/user_guide/QE128QRUG.pdf?fsrch=1) but nothing to the low-power modes.

How can I put the CPU to stop4 mode? Right now I am doing all my work in ISR's and the CPU is in a "while(1)" loop. Now I want to put it to stop4 or even stop3 if possible.

But how does it work? I tried the following code for stop4:
SPMSC2 &= ~ 0x80; // LPR
SPMSC2 &= ~ 0x01; // PPDC;
asm { mov3q #4,d0; bclr.b d0,SOPT1; stop #0x2000; }
but after that my ISR's are not executed any longer...

Does somebody have any idea what the reason could be?

Ciao,
Uli

Re: MCF51QE128 - Low Power Modes - stop4, stop3

leopard86 — Tue, 30 Mar 2010 17:37:14 GMT

It is an old post but I'll give an answer to help out people working on stop modes:

PPDC is a write once bit, so must be set in the __initialize_hardware procedure.

Care must be paid if you're working with the debugger attached or detached. If it is attached XCSR[ENBDM] is set to 1, hence if calling STOP3 and STOP2 will go into STOP4 mode instead. I currently have problems with the debugger detached (Flexis DEMOJM, P&E Multilink cyclonepro via USB) because when calling a stop3 or stop4 I get a Reset.

Bye

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MCF51QE128 - Low Power Modes - stop4, stop3

Re: MCF51QE128 - Low Power Modes - stop4, stop3