Spencer Ryan

QG8 - Set clock rate to 1MHz / Power usage?

Discussion created by Spencer Ryan on Jan 19, 2012
Latest reply on Jul 19, 2013 by Pavel Sadek

Hi Guys,


I'm coming from V2 Coldfire land where (to me anyway!) setting the CPU frequency was simple.


I'm prototyping with a QG8 and I'm not sure how to set the clockrate properly. Processor expert is equally as confusing about what fields mean what.


The biggest issue I'm seeing is that at 3.3V with nothing else hooked up to the part (BDM removed) and it executing code the chip is drawing a little over 2mA, which seems really high. I'm using the internal clock source.


The datasheet says that at ~1MHz it should be using somewhere around 0.5mA, but I'm not sure that is possible without using an external clock or crystal.


Any tips are much appreciated!



Thank You,