> > *Dear Wulf man, * > *Thanks for the input. So do you recommend that external ADC and > communicate through PRU with SPI, GPIO?* > > *and do you have some good ADC IC in mind?*
He's left to go out of town, and possibly wont be able to reply for a few days. So here is one of my concerns with the general path you're on Rathin. You're using the PRU's right now to interface with the on board / die ADC. It only has 7 channels, and it seemed like you said this is not enough in the end, but is possibly good enough right now to experiment with. I'm seeing a problem with that. Let's just assume for a minute that you intend on using the PRU's to interface with these external ADC(s) later. How are you going to do that ? So we have potentially, I2C, SPI, and *maybe* UART to work with as a communications medium. Assuming the Beaglebone is still an option at this point. The first problem I'm seeing is: how do you intend to communicate with the external ADC in question ? There is no PRU interface or protocol to interface external devices that I'm aware of. This means you'll have to implement the bus interface / protocol in software through the PRU. e.g. bit bang. Which is completely possible, but it is a hurdle. The second potential problem I'm seeing here is that let us assume for a minute ( again ), that you intend to now stop using the PRU because of the above. So now your bus communications are directly through the peripherals, and through Linux it's self. Using Linux( or any OS ) will have some latency overhead. Passed that, now that you're no longer using the on board ADC, you're going to have that bus to contend with as well. SPI, I do believe can handle this - bandwidth wise, but this is where I get in a little over my head. I2C, I'm not too sure about, and UART has a maximum theoretical ceiling of 3Mbit/s. Plus, since I have not looked into it. I'm not even sure if there is such a thing as an ADC with a UART bus interface. Anyway, I only mention this because I know you have a time constraint. Not to make you worry about. But you should be mindful of these things, *and* perhaps others I personally have not thought of yet. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
