Unruh wrote: [] > Garmin defines the leading edge as the transition from 0V to 5V on > the PPS line. Now serial has two levels -12V and +12V. with > capacitive coupling, the garmin signal would be something like -2.5V > to 2.5 V which really is way out of spec for the serial port. (Or > with the typicallysmall duty cycle, more like -1V to 4V)
You do /not/ capacitor-couple RSR232 lines! Directly couple. Serial has more than two important levels - read up on hysteresis levels of typical receiver chips, particularly those used in PCs. I.e. the levels where a logical "0" changes to a logical "1" is not +12V or -12V, and it may not be the same level where a logical "1" changes to a logical "0", if you see what I mean. Cheers, David _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
