PaulZC
September 20, 2025, 1:18pm
5
Hi @praneeth ,
Another possibility would be to use SPI to communicate with the three NEO-F9Ps. SPI is ~10 times faster than UART or I2 C. It would leave the ESP32 UARTs free for your serial console and debug messages. Each GNSS needs its own Chip Select pin, but the ESP32 has plenty of GPIO available.
The posts linked below may help.
Best wishes,
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!
Dear Sparkfun
since years we are successfully working with your products, mostly Thing Plus MCU boards and also GPS with ZED-F9R.
with that setup in the end we are mostly able to work how we need (SPI interface between the two and also a third Dual-port shield parallel on SPI).
In last months we wanted to start use also the other variant of ZED-F9P.
so ordered two board (GPS-16481) and after a brief setup already stumble in SPI problems:
I soldered the DSEL jumper and connected all the SPI lines, also update all the ZED-F9P firmware via U-Center.
anyway in the end only one of the two works via SPI, the second doesn’t (maybe few time did..) but via I2C works fine.
Also checking in the forum find out that this was an issue (not sure if from Ublox or from your boards).
in the end thought that maybe just one of the two board was defective and so order two more (this time without SMA, GPS-15136).
unfortunately yet both of the two are showing the same SPI limitations, almost no one…
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