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MCF51QE128 micro External Crystal refernce Bus clock issue

Question asked by Balamurugan Venkatesh on May 20, 2016
Latest reply on Jun 20, 2016 by vicentegomez



I'm working on the MCF51QE128 micro and it is found that the micro when set to derive its Bus clock from the external crystal of 32.768 KHz the FLL derives an clock frequency in terms of decimal values (as per the reference manual which is Okay). But the problem or issue we are facing currently is that, when the FLL derived clock has been used to derive the counter values for the hardware timers there is an variation in the timing of the hardware timer interrupt's for the same count value from one hardware board to the another hardware board (Crystals and Software are similar on both boards). For e.g. say if the counter is configured to interrupt every 2 ms it would interrupt at 1.880ms. The behavior seems to be weird because the interrupts occur at 2 ms in one board with the same driver and configurations but 1.880 ms on an another board. Please provide some insights to this issue.


Thanks Balu.