On Wed, Sep 25, 2019 at 8:01 PM David J Taylor via time-nuts < [email protected]> wrote:
> From: Adam Kumiszcza > > Hi again! > > My raspi is now in a new location. The GPS signal is fine, the window is > not south-facing, but the antenna is outside the window attached to a metal > windowsill, and there are no buildings nearby. > I'm coming back to the idea of distributing PPS signal. Do you think such a > contraption could work? > > https://botland.com.pl/pl/raspberry-pi-hat-komunikacja/11707-serial-pi-plus-max3232-interfejs-rs232-dla-raspberry-pi-7426787870194.html > > I mean, stacking it over the uputronics board and soldiering some pins. > The MAX3232 chip is the same as on these kind of devices: > > https://www.ebay.com/itm/MAX3232-RS232-to-TTL-Serial-Port-Converter-Module-DB9-Connector-MAX232/262241627343 > > Cheers, > Adam > =================================== > > Adam, > > You need to consider what cable you will use, how many devices you need to > feed, and what distance is involved. I've fed a couple of PCs from the > same > RS232 device, just the data out and CD (PPS) lines, of course. Not > paralleling the data into the GPS device. One PC is ~4m away, and the two > signals are fed over a twin-pair coaxial cable. Likely a 3-core > unscreened > cable would also be OK over such a short distance. The other PC is about > a > metre away. > > If you're talking about ten PCs I would have a number of TTL to RS232 > converters, each feeding 2-3 PCs, or a controlled impedance cable (50 or > 75 > ohms) with tap-offs along the cable and a termination at the far end. The > old thin-wire Ethernet comes to mind. > > But others here have more experience than me, though, and may be able to > recommend surplus units to do the job. > > Cheers, > David > It will be connected via a short cable (1,5 m or less) to one computer. The second will join much later, I will worry about splitting the signal then. Other computers would be in different rooms, so I would need another time source. My question was rather if stacking another board with serial port on it would be a good idea. I'm thinking of using PPS signal there directly via GPIO. And maybe NMEA, too. Cheers, Adam _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
