paul brule

MC9S08QG8  RTI frquency trim

Discussion created by paul brule on Feb 11, 2006
Latest reply on Feb 15, 2006 by Alban Rampon
I need the MC9S08QG8 RTI to keep time (count seconds) when it is running and also in stop3 mode. I have no problems doing this, however, I cant seem to trim the frequency. It appears the 1KHz RTI oscilator is independant of the internal reference oscilator. Am I right?
If this is the case, I can RTI every 8ms and count down 125 to increment seconds. By changing the counter preset (125) up or down I will able to trim for accuracy. My question is: How stable is this oscilator when it comes to temperature or PSU changes? I see no information in the data sheet for this oscilator, only for the ICS clock reference.