interrupt of the timer

[cchechio]

Posted on June 30, 2014 at 02:32

Can I have a link or an code example to count the rising edges that have an input signal in a prefixed time?

I need the number of rising edges in a second.The frequency of the signal on a gpio input is in a range from 10 Hz to 70Hz.how count the number of rising edges until the timer is 0?I use stm32f4 discovery.

[Tesla DeLorean]

Posted on June 30, 2014 at 05:15

You could use one TIM in external counter mode, and use a second to define the integration period, this could trigger a DMA sample of the counter of the first, and subsequent measurements would allow you to compute the increments over the period. There may also be other gating options.

[cchechio]

Posted on June 30, 2014 at 10:46

Can I ask you an example?

[cchechio]

Posted on June 30, 2014 at 10:47where can I study this part?

[Tesla DeLorean]

Posted on June 30, 2014 at 16:52

There are several manuals for it, Data Sheet/Manual and Reference Manual. The timer section is a bit heavy going, but if you have familiarity with other micro-processor and timer designs it should give some perspective.

http://www.cs.indiana.edu/~geobrown/book.pdf

I don't really want to have to write everyone's code. I've posted some external counter examples. You could review the count every 1000 iterations of a 1ms SysTick interrupt? The kind of frequency you're talking about would seem easy to measure using PWM Input mode. Integration is perhaps more effective with faster clocks.

https://my.st.com/public/STe2ecommunities/mcu/Lists/STM32Discovery/Flat.aspx?RootFolder=https://my.st.com/public/STe2ecommunities/mcu/Lists/STM32Discovery/STM32F4%20Timer%20External%20Pulse%20counting&FolderCTID=0x01200200770978C69A1141439FE559EB459D75800084C20D8867EAD444A5987D47BE638E0F&currentview...