Datalogger

Since the new gui layout is just about finished, and Rbe has redone the Devo12 pages, I thought I'd tackle the next item on my list.

So I've started work on a data-logger.

Here is an example of the configuration screen:



My plan is that the configuration is done per-model. There will be a directory 'datalog' which contains a bunch of files (datalog1.txt, datalog2.txt, ...) Each file will be 4kB and they will be filled in series (write 4k of data to datalog1.txt then switch to datalog2.txt)
The logs will be written periodically in 'append' mode (so restarting the Tx or switching models will not overwrite previous data.
There will be a button to reset the log files and start writing from the beginning.

The idea is that you can select which data you want to capture from the above config page.

I'm not yet sure how to write the data. If I write it in csv format, it'll be easy to work with, but will potentially use up a lot of space.
I can write binary data in a much more compressed manner, but then you'll need some application to extract it into a usable format.

We are again limited by the filesystem code in that I cannot create or resize files on the Tx, so all files need to be pre-created. i could use a single big file instead of many small ones, however then resizing the file needs special toos.

Will be nice to have datalogger view screen, there we can select (by one or several items) and display data as graphs with different colors.

Is it possible to export data from binary to csv format by any means (over USB or anything else)?

RandMental wrote: I see an option to export / replay this file via ppm-out into
a simulator (Phoenix) to see you flight and the reason for that "crash"!

I think you couldn't use for that, since it would be sampled with limited frequency, so it wouldn't play back the command changes between those samples...

I think the most likely use for datalogging is in conjunction with telemetry. For the FPV folks, it could provide maps of the flight. For others, it would contain things like battery state.

I'm not sure the Tx is really a useful place to look at the data, but it could be done.
You can't convert to csv on the fly, but it would be easy to have an app that could do so.

My guess is that the value of more data outweighs the readability of it. Also If we want to view it on the Tx, binary will require a lot less code.

I'm a bit skeptical about the possibility of playing back a log on the sim whatever fine the sampling is.
The physics are different and the conditions like wind differ too, so the same commands would result in a very different behaviour. The model in the sim would probably crash very soon...

for the joystick, I currently use 8-bits per channel and it seems to be sufficient. So that provides 680 samples per 4kb file for 6channels. At 100msec sampling rate, that provides ~1 minute of flight time. But any session won't be limited to a single 4k file, so this may be workable. It wasn't really my purpose though. Initially the sample rate will likely be limited to 1sec.

FDR wrote: I'm a bit skeptical about the possibility of playing back a log on the sim whatever fine the sampling is.
The physics are different and the conditions like wind differ too, so the same commands would result in a very different behaviour. The model in the sim would probably crash very soon...

Yes I agree, as a playback it wouldn't make much sense other than to analyze your stick movements to see what if anything you were doing wrong.

I've checked in support for the data-logger for the Devo6/Devo8/Devo12

I thought I'd get it out there for testing and feedback while I work on the Devo10 interface (this is another feature that won't be available on the 7e)

Notes:
You can only change the selected elements when the logger is not running.

There is currently no way to toggle it from the main screen

The data is written in a binary format, and does not include the header information. This means if you run a custom firmware with different capabilities, you'll need to also alter the parsing script to be able to decode the log.

The log is in datalog.bin. If this file isn't available, logging will be disabled. The default is 16kb but it can be as large as you like.

There is a script in utils/datalog2csv.py that can be used to convert the binary data into a csv.

I will supply a compiled python (exe) version with the release so users don't need python to use it

Empty place after Timer4


TelemRPM1 only (TelemRPM2???)


What is the Time? Other GPS options (Altitude, Speed)?


Wiil be nice to group all telemetry options at the top of the list.

Oops. I noticed the space before, but forgot to address it (fixed). the Time is RTC, I've renamed it. The GPSLoc previously included the altitude and speed. now it is separate. I also added loading/saving as well as paging on the scrollbar.

Also, I chose not to put the GPS stuff at the top because very few folks will actually use it. The RTC is at the end to keep the code simple due to it being conditionally available.

Sample rate??? After 60sec empty space.