PetitFatFS was handy in a recent build. I was creating a box that could be placed on marine equipment to collect vibrations data, but to capture the modes of interest it had to read accelerometer data and write it to a microSD card at >=660[Hz]. I don't have a programming background and thus had trouble creating code which fit onto the tiny memory of the microcontroller being used. PetitFatFS worked beautifully, and saved a ton of headache on my end. It added the step of creating the storage files on the microSD card prior to inserting it, but that was acceptable for this project.