On Wed, Jan 30, 2019 at 2:54 PM Thomas Remmert <[email protected]> wrote: > > Hello, > I have a contact closure switch connected to P8_14. When the switch is > activated, P8_14 is brought to ground. I need to apply a time stamp when > this occurs with millisecond accuracy. > > 1) I have an adafruit GPS with 1 pps output. I see the NMEA strings and have > confirmed the 1 PPS is working. > > 2) I have NTP running with my local GPS and 1PPS source configured. (Maybe > chrony is a better choice?) > > 3) Just for testing, I am using the following python code: > > import Adafruit_BBIO.GPIO as GPIO > import time > import datetime > > GPIO.setup("P8_14", GPIO.IN, pull_up_down=GPIO.PUD_UP) > > #GPIO.add_event_detect("P8_14", GPIO.RISING, callback=my_callback, > bouncetime=1000) > > while True: > GPIO.wait_for_edge("P8_14", GPIO.RISING) > ttime = datetime.datetime.now() > print(ttime) > > > When I compare my time with a very expensive DAQ, my time stamp is always off > by 2-4ms and it is not a consistent offset. Does anyone have any other > thoughts at to how I might approach this? I am needing to get the timestamp > accurate to 1ms.
Use the pps driver, setup an overlay like shown: https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/PB-UART4-TESEO-LIV3F.dts#L63-L71 Then you can use the pps/gps tools... Regards, -- Robert Nelson https://rcn-ee.com/ -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAOCHtYhXrg5FUXpnqxXLY8a18Cmn2w-47SE86xXwQiXYWCjN%3DA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
