08-23-2016, 08:29 AM
(06-18-2016, 12:45 PM)lospinos Wrote: I found this project for Raspberry Pi, a Stratum One NTP server using a GPIO expansion card.
http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html
The expansion card is available from:
https://store.uputronics.com/index.php?r...duct_id=81
I would like to use my Pine64 instead of the RPi.
Anybody here knows if the GPIO header has the same pinout as the RPi? Ideally, I want to buy this card and plug it into my Pine.
The PI-2-Bus header has the same basic pin-out as the 40-pin connector on the Raspberry Pi -- hence the label -- and most of the connections are the same or close equivalents. The expansion card here connects to pins 1, 3, 5, 8, 10, and 12 (and presumably one or more of the GND pins) and these are all the same: 1 is 3.3V, 3 and 5 are the TWI-1 bus (/dev/i2c-1), pins 8 and 10 are the serial port (UART2, /dev/ttyS2) and pin 12 is PB4 / GPIO36, which is used to receive the 1PPS, the 1 pulse per second synchronization signal.
Now I don't know if the Linux kernels support the use of 1PPS (yet), but disregarding the 1PPS for now, I have already managed to get a similar GPS card working, using the Adafruit Ultimate GPS HAT which has essentially the same UART connections, and using GPSD to receive and collate the data stream. GPS-receivers are not much different as they all emit NMEA-standard text on a serial line, and GPSD is good at handling the variety in the messages that they produce.
