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GROVE GPS module with SIM28

Posted: 14 Jun 2018, 11:08
by dynamicdave
Has anyone managed to connect a Grove GPS module to a Wemos D1 Mini ?
The one I have uses the SIM28 GPS processing chip.

I believe the module uses a serial communication - but it could be I2C.

Product reference is: 113020003 from Seed Studio.

Any information/advice on connections and how to extract the NEMA strings would be appreciated.

Kind regards from David.

Re: GROVE GPS module with SIM28

Posted: 15 Jun 2018, 00:08
by TD-er
Apparently it is default configured for 9600 baud serial: ... 217502.pdf
So that's not to hard to get.

Currently there is no GPS plugin for ESPeasy.

Parsing NMEA isn't that hard, since it is just ASCII and at most 80 bytes per message.
You only have to decode a few of the available string types. The rest can be ignored.

One thing you have to realize and what's not mentioned very often, is that the DOP values in those strings (HDOP/VDOP) give some indication about the "dilution of precision", or in other words they are just 1 standard deviation in meters.
ESPeasy only outputs values in float. Those have about 6 decimals in precision, which means you can only get up-to 4 meters of resolution, even when the DOP values are 2 or 1.
For navigation probably close enough, but for use in a drone maybe a bit too course :)