A friend from NIST recently told me about a Raspberry Pi Stratum-1 NTP server project, and that reminded me of the experiments I did with the Navspark dual GPS+Beidou receiver module. Navspark is a small, Arduino-compatible module that besides GPS can also receive data from China’s Beidou 北斗 satellite navigation system , that is currently being built. I thought it would be fun to build a Beidou-powered Stratum-1 NTP server to see how does it compare to GPS.
To have a really good really good, satellite-powered reference clock, I have to have access to a 1-pulse-per-second (1PPS) signal from the receiver. The pure USB-connected receivers don’t really seem to do that yet (looks like plenty of opportunities there!), instead I have to use separate hardware for it.
The Navspark module has a 1PPS pin (GPO3 below), and the only other pin I’ll really need is a serial pin to receive the NMEA stream of the satellite lock data (TXD1 below).
I while back I’ve exchanged some of my points earned from posting projects to a MediaTek LinkIt One on the Hackster.io Store. This is my first project with that, trying to do something different than what I can do with the hardware I (literally) amassed so far. Being an expat and traveller, GPS / location sensing is always a timely topic, so set out to build something around that.
It was a long typhoon day when I started experimenting with the LinkIt one, and and as rainy days go – I’ve felt it would be great to know how far am I from home? Of course there’s a GPS in every single smartphone these days, but a dedicated device can still evoke a different feeling. So the idea for Dorothy came about.
Basic version: where are are you?
The basic idea is connect the GPS module and a Grove LCD RGB Backlight screen, and colour-code the distance from home. The LCD speaks I2C, so can directly connect it up to the I2C socket on the LinkIt One.
I have signed up to support it for two main reasons: it’s a Taiwanese project (Skytraq, the company behind Navspark is in in Hsinchu city in Taiwan), and I haven’t seen anything about Beidou before.
They barely made the campaign, but it’s not for the lack of quality. There were a lot of updates during and afterwards as well as the project was developing. Those were good behind the scenes information, got to see what parts of hardware development are more troublesome than others.
The Navspark board
The rewards just shipped this week, and since for this campaign I’m a “local”, I got it pretty early. I got my Navspark GPS/Beidou (BD) version in a big envelope, together with an antenna, some pin and a jumper.