Hi,
I’m working on a “stopwatch” based on multiple photons. I need them to be exact synchronized (within 10-20 ms). I might not have internet connection, but they will all be on local wifi.
I have thought about synchronizing time from a master unit (raspberry or greater), but as distance to master may varies and there is different network latency I don’t think this will work.
Instead I’m thinking to connect a GPS module to each Photon. Is it possible to set the integrated RTC with time from the GPS unit with that precision and later read the time including ms from the Photon?
The different time stamps will be transmitted via Wifi to a database on the master unit.
Any suggestions or do I need a more sofisticated uP?
@lubker - I have been working on proving out the instructions for running the local cloud on a Raspberry Pi 3 setting that up as an access point. I finally have it all working and can say that Photons do a time sync against the local cloud. I don’t know what sort of latency you will have between the Photon and RPi3.
I am using the stock spark-server and spark-protocol. There is one small patch to perform in the spark-protocol code noted in my instructions. There is a lot of patches floating out there. At this point it is sufficient for the device to connect to the local cloud and obtain the cloud time – from the RPi3.