ST72F324BJ4T and WFI Instruction for Power Saving - call it in RAM

tom_evans · ‎2006-01-10

Posted on January 11, 2006 at 01:18

tom_evans · ‎2006-01-10

Posted on January 11, 2006 at 01:18

Is anyone using WFI to save power?

We're running the ST72F324 (16k FLASH) at 6.9MHz.

From the data sheet we expected about 2.1mA when executing WFI in FLASH. What we measured was 3.5mA!

We changed from executing ''WFI'' in FLASH to writing ''WFI RET'' into RAM and calling it. The WFI current is now 1.4mA. BIG difference, and it matches the data sheet value too. Watch out for this if trying to lower the current.

I'm now trying ''Active Halt'', and am getting 430uA (should be 230, trying to find the problems with that now).

Any suggestions for finding ''missing current'' in Active Halt mode?