UhClem

GPS receivers typically put out NMEA strings. Those would be a lot more useful to look at than your post processed graph.

It isn't hard to use assembly but it is rarely worth the effort. The compilers do a good job. The trick with writing better assembly language code is to first figure out if the effort is worth it. Is it in some critical bit of code that has...

Not shown in that diagram is the connection between the ground pins of the two systems. That is important because one is generating an analog voltage with respect to its ground while the the other is measuring a voltage with respect to its...

SD card write times can vary and with large files it gets worse. The best method for dealing with this is to separate the SD writing process from the data collection using buffers. The data collection process stores data into buffers and when a...

The specification has something about this. 4.13.1.7.2 (version 8 of the spec) says that the maximum FAT write time shall be less than 750ms. A little later in 4.13.1.8.2 it has a table for various speed classes. All of which show an average time...

Unfortunately, the SD specifications say: What triggers a license requirement? I don't know. Maybe it is hiding in one of those documents or somewhere else on the web site. But people have been writing code to these specs for a couple of decades.

I prefer to write my data logging programs differently. Data collection is driven by interrupts and the data gets packed off to a data buffer. Multiple buffers some power of two times 512 bytes in size. When a buffer is full, the foreground task...

For more than you ever want to know about your sensor noise, there is Allan Variance. It does require that you collect samples at a uniform and known rate of course.