The inverter is required because the Motorola GPS receiver uses TTL and the PC serial port uses RS232.
RS232 uses a positive voltage of +3 to +25 volts to indicate a logic zero, and a negative voltage of -3 to -25 volts to indicate a logic one. Brian KD4FM Bruce Griffiths wrote: > Hal Murray wrote: > >>> Well, I plugged my Oncore UT+ into my PC and it didn't work until I >>> put a level shifter in... no damage but no data either. So far I've >>> been lucky in that every device I tried that needed a level shifter >>> wasn't damaged by the lack of one. >>> >>> >> The normal MAX232 type level shifters include an inverter. >> >> So even if the voltage levels work without a level shifter, the signal will >> be upside down. >> >> >> >> > To play safe, if one isnt sure that an inverter is required or not an > exclusive OR can be used so that the signal can be inverted or not as > required. > > Bruce > > _______________________________________________ > 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. > > _______________________________________________ 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.
