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tre2020067
Associate III
September 15, 2011
Question

beginner needs help understanding what Timer period and base are!

  • September 15, 2011
  • 2 replies
  • 513 views
Posted on September 15, 2011 at 03:08

What is a timebase and what is ?

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    2 replies

    Tesla DeLorean
    Guru
    September 15, 2011
    Posted on September 15, 2011 at 05:54

    TIM_Prescaler = N - 1; Divides the Bus/TIM clock down by N

    TIM_Period = N - 1; Divide that clock down by N, ie the *period* is N ticks.

    So assume your TIMCLK is ticking at 72 MHz, the *external* clock

    If TIM_Prescaler = 71; the timers *internal* clock will be 1 MHz

    If TIM_Period = 999; the 1MHz is divided by a 1000, so it becomes 1KHz

    Your update interrupt with fire every 1ms

    Now if you want to play with the channels, say in a PWM mode you can play with the output pins.

    If TIM_Pulse = 500; the channel will out a frequency of 1 KHz, with a 50/50 duty cycle. ie TIM_Pulse = N / 2

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    tre2020067
    Associate III
    September 16, 2011
    Posted on September 16, 2011 at 07:55

    thankyou!