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.
--
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