How to log your moves to an SD Card?
- Update your firmware to the latest Beta. At the time of this writing it is RC_007_40.
- Insert your microSD card that came with your spectrum ST4. Many cards will work that are formatted FAT32, but getting every card to work may not be possible. Stick with the SD card that came with the spectrum. We test these before they go out.
*Another reminder, add a "tape tail" to any card you put into the spectrum to make fishing it out easier!
- Insert the microSD Card.
- Power on the spectrum.
- Set up a programmed move.
- On the return to start, the spectrum is writing the full move to the SD card under the LOG folder.
- Naming convention is: "LOG/ST4Log_versionMajorversionMinor_fileIndex"
How do I read the file?
- Pull out the card (powering down is better, but not required). Important Note - Once the card is removed, you will have to power cycle the spectrum for it to log moves again!
- Put it in a reader on your computer.
- Open the SD card and the LOG folder.
- Pick out the last file and open it.
- In that file you will see a header with the filename and a row for each of the frames positions.
What does it look like and how can I interpret the numbers?
Each row in the file is a value of the motor position at each frame. There are 5 values in each row: frame number, Pan Value, Tilt Value, M3 Value, M4 Value.
For example, here are the first few rows of a log file (attached as an example):
Each Axis has a physical constant associated with it:
These values are the how many clicks or ticks per value for that axis.
From our example:
f0 (frame 0) has a pan value of 18145
f1 (frame 1) has a pan value of 18129
We don't care about absolute values, we only care about changes. Between frame 1 and frame 0 we have 18129-18145=-16
Since this is Pan we use 3275.420875 as our constant and divide the value. This is -16/3275.420875 = -0.0048848684216803 degrees of pan change between frame 0 and frame 1.
This is lots of math, but check out the attached excel example if that's your thing.