December 20th, 2016 by

Software demodulation & new motors

It’s been a while since the last update, because a lot of stuff has been happening.

On the code side, IQ demodulation is done. This has been a major task for a while, with some troubles achieving phase correctness and correct buffer handling. The working code proves that 7 MHz is enough to do demodulation for our needs. There is still some room for improvement, such as using Timer1/Timer3 input capture to get more accurate measurement of tachometer/sample times. Some optimization could also be done, if we need to increase the sampling rate (unlikely at this stage). Current CPU usage is around 60%.

We also got some new motors with built-in controllers. This reduces our work load considerably. They also have much better regulation than our previous controllers, meaning faster starting and more stable rotor speed. The electrical noise is also considerably lower and the motors run quieter.

Circuit boards for our most recent analog front end design have also arrived, and all components except the operational amplifiers we need! This may have something to do with the holiday pressure on the postal system. Hopefully they arrive before New Year’s Eve. We should also have some new toys from Atmel in the mail. More on those in a future post!

Finally, some pictures:

Current electronics stack and new motor with rotor attached.

New power card + motor connector. Uses off-the-shelf regulator modules.


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