Generating 100us timer base & cnt

Discussion in 'Embedded Systems and Microcontrollers' started by Vindhyachal Takniki, Nov 4, 2014.

  1. Vindhyachal Takniki

    Thread Starter Member

    Nov 3, 2014
    1. I have STM32F205 running at 120Mhz with external 16Mhz crystal.
    Prefetch , Data & Instruction buffer on. timer is clocked by 60Mhz

    2. task is to toggle 10 pins with a base count of 100us.
    i.e User will enter number in multiple of 100us & I have to toggle the pins.

    3. I have timer base of 100us & accordingly I am toggled the pins. In interrupt only 10 variables are incremented. So ISR is very small.

    4. System works fine initially but on long run (1 hour or so), I saw some latency keep on adding.

    5. This probably due to small time base i.e 100us. It adds jitter & theoretically Cortex-M3 core should always be able to service an interrupt request within 15 cycles
    . Is it due to these cycles which accumulate over period of time & generate error.

    6. Any possible solution/advise/technical point