On 8/23/2011 15:27, unruh wrote:
On 2011-08-23, Uwe Klein<[email protected]> wrote:
unruh wrote:
But from his test, his system is labelling both edges.
so he has bounces on the line?
either that or rise/falltime is so low and noise so high
that receiver hysteris is not sufficient to supress multiple
HL/LH changes?
No, his test shows that the line changes and then 100ms later it changes
back and 900ms later it changes again (ie once per second it rises and
falls.) Ie, it is behaving exactly as it should if it were detecting a
pulse 100ms long.It is detecting both the rising and falling edge.
I just checked and the pulse is almost exactly 100 ms low going and 900
ms high (within about 1 ms) so it's 90% duty cycle high most of the time
with a swing low. The signal itself is clean down to microvolt levels.
The total voltage swing is about 12 volts (which would stand to reason
since I'm feeding the TTL level PPS output of the GPS board through one
channel of a MAX232 level shifter).
Therefore the machine is receiving a nice, clean PPS signal on DCD (DCD
pin was also verified yet again and is correct by hardware specifications).
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