[beagleboard] Re: using beaglebone black to control an valve

2014-02-08 Thread Lenny
Hi, 

can you give more information on your sensor, such as what kind of signal 
(digital/analog, what resolution is needed, really 500MHz signal 
bandwidth)? I am using the BBB PRU for some realtime feedback application. 
In principle, the PRU works at 200 MHz, so with one PRU, you can change the 
signal at the 15 available digital output pins once every 5 nanoseconds (or 
equivalently read them out that fast), but you would need to reserve some 
cycles for signal input. In my application, I used the integrated analog 
input of the beaglebone black, which drastically limits the input sampling 
frequency to slighly above 1MHz. If sampling at 1 MHz is enough for you 
(which i believe it should be, as I can hardly imagine a valve which can 
react within 1 microsecond), then the PRU can solve your problem. Of 
course, you would probably have to amplify the output from the Beaglebone 
as the output pins deliver only a few milliamperes of current. 

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[beagleboard] Re: using beaglebone black to control an valve

2014-02-07 Thread doog
you might search for Machinekit with LinuxCNC since it's already got those 
two realtime engines(Linux and BBB PRU's) installed on it and built for the 
BBB.
It's been designed to run RepRap style 3D printers and both home and 
industrial CNC machines. Heck, I'll find the link and post it

http://bb-lcnc.blogspot.com/p/machinekit_16.html

The PRU's are setup to control stepper motors but it could give insight as 
to their use for valve on/off control.

Doug

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