ESP32 datalogger with RTK Facet over Bluetooth before moving to F9P

GPS/GNSS Development Boards
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Hi all,

I’m planning to build an SparkFun Thing Plus - ESP32 WROOM datalogger that logs analog voltages and saves everything to a microSD card. For now, I’d like to get GNSS coordinates from a SparkFun RTK Facet (Rover mode) over Bluetooth or SiK Telemetry Radio V3 so I can log position + sensor data together. Later on, I’ll switch to a SparkFun GPS-RTK-SMA Kit ZED-F9P board inside the logger, and just use the Facet as a base station for RTK corrections (my goal is ~0.5 m accuracy always in an open field).

Has anyone connected an ESP32 to the Facet over Bluetooth? I’m wondering about reliability and whether there are any issues with logging speed or power draw. Any tips or sample code would be really helpful.

Thanks!

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Hi Romário (@Romario ),

How important is the ‘wireless’ link between the RTK Facet and the ESP32 datalogger? It would be much easier to use a UART link.

If your budget will allow, it would also be easier to integrate the GPS-RTK-SMA Kit from the start. There are Data Logging examples in our u-blox GNSS library that you can use as a good starting point. Most of them were written for and tested on the ESP32 WROOM Thing Plus. Also, using the GPS-RTK-SMA Kit from the start would make both I2C and UART interfacing possible.

If you do want to use the RTK Facet to get started, then you can use the Data Port to listen in on the UART data between the ZED-F9P and the ESP32. That may be easier than trying to use Bluetooth or SiK.

Both Bluetooth and SiK are possible, but I don’t think we have any ‘off-the-shelf’ datalogging code examples which you can use as a starting point.

I hope this helps,
Paul

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Also, this may help:

We wrote a stand-alone GNSS datalogger example for the SparkFun DataLogger IoT. I don’t know how important logging speed is for your application, but this hardware and example has some big advantages:

  • The datalogger SD card is connected to the ESP32 via SDIO. That allows much faster reads and writes compared to standard SPI.
  • The ZED-F9P GNSS can be configured for and connected via SPI. That allows much faster data transfers compared to UART or I2C.

The example was able to log ‘RAWX + SFRBX’ (raw GNSS signal data for post-processing) to SD card at 20Hz without losing a single byte. That’s about 50000 Bytes per second, streamed from the GNSS to the SD card…

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Hi Paul,

Thank you so much for your help.