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Fez Hydra Help please


#1

Hi all

I am trying to connect 4 ESCs (and down the line 4 brushless motors) to a Hydra (quadcopter attempts, what else).

There are only 3 PWM pins. My bad. I am clueless as to my options now. I am a seasoned C# progeammer and a sterter electronics/gadgeteer enthusiast.

I would appreciate ideas how to overcome this limitation.

HELP!

Thanks


#2

You could try to generate the pulses in software, or low level C++(See RLP), but the simplest solution would be this:
http://www.ghielectronics.com/catalog/product/363

I don’t think the driver is complete yet. See http://www.tinyclr.com/forum/topic?id=6860&page=4#msg68587


#3

Thanks! This looks Promising.

IS it possible to use simpler extender boards like this one http://www.ghielectronics.com/catalog/product/361 or this one http://www.seeedstudio.com/depot/grove-expansion-net-gadgeteer-compatible-p-1084.html?cPath=203?

I have no problem playing with soldering, if needed…

Any other original ideas to use with existing HW?

I’m a bit frustrated…

Thanks


#4

Unfortunately there will be no way to do the timing accurately enough on the first module. That module is only for “slow” IO, like leds and relays, where timing isn’t crirical.

It would be possible with the second module, but again, you will have to generate very acurate timing inside the Hydra. C# will not be good enough for this and you will have to use low level C, see RPL, which is a pain to develop and debug.

The module that I pointed you to already contains 16 PWM channels, so you just tell it where the servo must point and the module does the rest.

I have done a C driver for the Panda which could drive 12 servos, or more. I had jitter problems every time the garbage collector ran, and it just was a pain. I can point you to the code, but keep in mind that it used peripherals that where specific to that chip. The Hydra will have something similar, but you will have to dig into the CPU’s low level datasheet.

In the end there is the easy(expensive) way and the hard(cheap) way. Take your pick… :slight_smile:


#5

Thanks for your time and extensive replies.

The module you suggested it is.

Cheers.