Hi everyone,
I recently purchased an Openlog Artemis (DEV-16832) and a SAM M10Q GPS breakout (GPS-21834) for use in a datalogging project. First of all, what an awesome product for out of the box datalogging!
I’d like to bump up the sampling rate for IMU data saved to a SD card to at least 500 Hz, ideally closer to 1kHz. I hope you guys can help or point me in the right direction to achieve this, or at least advise on what a realistic maximum sampling frequency with saving to a SD card could be.
Prior to purchasing the Artemis board, I’ve modified some of the SdFat library’s example “exfatlogger” code for an ESP32 paired with a LSM9DS0 IMU and generic SD card reader. With this setup I could save acceleration and gyro data to an SD card at a stable 250 - 270 Hz. In the source code for the Openlog Artemis board I see that SdFat and the same buffer technique is used for saving to an SD card. I’m planning on modifying the firmware to only keep the essential bits and pieces that I want to use to primarily log IMU data, with GPS data via interrupt or some other method at a slower rate.
For IMU data saved to SD only, is 500+ Hz possible? I’ve played with the settings in the default firmware and could select rate up to 250Hz without the GPS connected. From the forums I understand there is a 10Hz cap on the GPS sampling frequency. 10Hz is sufficient for my application, for now.
Where would be the best place to start modifying the source code to maximize the rate at which IMU data is saved to the SD card?
Cheers,
Jaco