On Mon, Mar 28, 2011 at 9:46 AM, Lenny Story <[email protected]> wrote:
> Or can I do a rising edge PPs pulse that's active for 10ms then lowers ? Yes. It's the leading edge that matters but 10ms is more of a spike than a pulse. It should be longer, maybe at least 10X longer. It should be something easy enough to notice even on a DMM. There is a question about polarity and voltages. The RS232 standard has data inverted from what TTL uses with a 1 being negative but RS232 does not invert control signals So the PPS if gong into a serial port is not inverted. But the common ttl->rs232 level converter chip inverts the signals o you need to invert the control signals before level shifting. Not rocket science just a need to be careful. Now, if your pulse is long enough to be seen by eye you can verify by eye you are doing the conversion correctly. If you get it wrong then the computer sees what you thought was the trailing edge as the raising edge. A long 200ms pulse makes this error easier to see. -- ===== Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
