Hi Christian,
I assume you know the MLX90393 is only a magnetometer - not a full IMU? And it is not supported by the OLA…
The Logomatic v2 is a very old product: > 9 years. I have never used it. Please proceed with caution. It may be difficult to compile new code for it. A lot of things have changed since then.
My advice would be to start with the ESP32 Thing Plus C, which has a microSD card slot built-in. There are GNSS data logging examples already written for that board: https://github.com/sparkfun/SparkFun_u- … ta_Logging
Try I2C to begin with. If you need extra speed then you can change to SPI. The NEO and the GNSS library support both.
I would probably recommend the MMC5983MA magnetometer, but only because I have tested it at its full 1kHz sample rate. That was using SPI and the interrupt pin for “end of conversion”: https://github.com/sparkfun/SparkFun_MM … rement.ino
You will need to structure your code carefully, especially if you have the microSD, NEO and two Mags all on the same SPI bus. Writing the data to microSD could be a “bottleneck”. You may need to use interrupts to read and store the Mag data, store it to buffer, interleave the GNSS data, then have the loop write the data from the buffer to the SD card.
Good luck - sounds like a fun project!
Paul