Tomas Petlach

MC9S08QG8 clocks generation from internal reference

Discussion created by Tomas Petlach on Oct 5, 2006
Latest reply on Feb 4, 2008 by David Payne
Hi everybody,
I have 1 question about clock generation in MC9S08QG8 MCU. I set ICSC registers to clocks generation on output of PLL with internal reference. The clocks have the maximum value for this case, the divider is set to 1. One small problem is the difference between clock value after flashing and the value after switch off and on. Immediate after flashing the MCU, the bus clock value is 8 MHz, but after switch off and switch on the MCU, the value of bus clock changes 9 MHz. This value keeps until next flashing of MCU. The switching off and on has no effect on the 9 MHz value of the bus clock.
I would like to know, if I did some mistake in the program code, or if it is some bug of this MCU. I have to note, that I have this experience on two pieces of this MCUs with different programs and in both cases there was the same differencies in bus clock values after flashing and after switching.

Message Edited by Tomik on 2006-10-0505:07 AM