RogerSchaefer

MC9S08SH8 with 20MHz bus clock???

Discussion created by RogerSchaefer on Oct 6, 2008
Latest reply on Oct 7, 2008 by RogerSchaefer
Hello,
The flyleaf page of the MC9S08SH8 data book says that with the internal clock source the MPU should "support bus frequencies from 2 MHz to 20 MHz".  When I tried setting the ICSTRM to get 20 or 16 MHz the chip failed.  No problem setting to 8 MHz.  When I tried to load a simple test program into the chip at a 12 MHz it seemed to work.  At 8 MHz the ICSTRM value for this particular chip was $BC and to get 12 MHz the value need was $3E.
 
The little test program  sends out a message at 9600 baud and blinks a LED works at 12 MHz but now I can no longer communicate with the chip with my OSBDM.  Does anyone have any idea why that may be?
 
Has anyone got the faster bus frequencies with the SH8?
 
Roger

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