[beagleboard] Using DMtimer pins to measure pulse width
I'm trying to use the timer pins (gpio2[2...5]) to measure pulse with on a BBB with the 25 MHz clock. The pin mud mode is correctly set to 2 and pull up/down are disabled and capture mode is set on the timers. When I connect a push button attached to 3.3v to one of the four timer pins I correctly get capture interreupts on low to high and high to low transitions and I can measure the timer difference between them without issue. However, if I set up a signal generator for 50 Hz 3.3v square wave and attach it to a timer pin, I get no interrupts at all. Looking on a 'scope at the timer pin, the pulse train amplitude has drop from 3.3 volts to about 1.3v. Does anyone have any ideas on what would cause such a drop in amplitude? Thanks for any suggestions. Bob Stewart -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups BeagleBoard group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[beagleboard] Using DMTimer pins to measure pulse width.
I'm trying to use the DMTimer pins (gpio2[2...5]) to measure pulse width using the 25MHz clock. I've successfully tested the software using a button connected to the 3.3v rail. The pinmux is set to mode 2 forcthose pins and pull up/down are disabled. The timers are set up in capture mode with interrupts enabled on the edge transitions. Using the button the interrupts occur and the time between the edges is derived from the captured timer values. However, when I connect a signal generator outputting a 3.3v amplitude square wave at 50Hz to a timer pin, no interrupts occur. Looking on a 'scope at the input to the timer pin the pulse train amplitude has dropped to about 1 volt. Can anyone suggest possible cause for this drop in amplitude? Thanks for any suggestions. Bob Stewart -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups BeagleBoard group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
