James Botte

RS08: Accuracy of programmed trim

Discussion created by James Botte on Jun 16, 2007
Latest reply on Jun 29, 2007 by James Botte
I need to program the RS08's DCO to a particular frequency using the "Enable Trimming/DCO Output Frequency (Hz)" field in the Communications Setting box. My question is: what is the accuracy of that setting?

I understand the DCO itself is +/- 2% over the temperature and voltage range of the device (and the resolution of the trim is +/-0.2%), but what is the accuracy of the algorithm that determines the untrimmed ICSOUT frequency of the chip and sets the trim value in Flash? So, for instance, if I were using the setting of "10000000" (10MHz) for the DCO at a particular voltage and temperature, what accuracy can I expect from the setting calculated (presuming no DCO drift from when the setting was calculated)? I need this value for my worst-case timing calculations to ensure that I don't violate the restictions that I have for the application I am working on.

FYI, I am currently using Codewarrior v5.7.0 that includes v6.1 of the debugger/programmer and USB connected SofTec DEMO9RS08KA2 board.