BeagleLogic logic analyzer on PocketBeagle

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1

I recently got the BeagleLogic logic analyzer (https://github.com/abhishek-kakkar/BeagleLogic) running on the PocketBeagle under a linux 4.9 kernel. It pretty much works as-is. However, only 4 of the 20 pins that can be configured as pruin produce any results. My (limited) understanding is that the black and pocket processors are the same (AM335x) so I would have expected R31 in the assembly code to be able to read all pins. Anyone have experience with getting the PRUs on the Pocket to read pins other than {p1_2, p1_4, p1_35, p2_35}? All my pins were configured as pruin when I was testing. Maybe some mapping that is different between the Pocket & Black?

2

fyi - you may want to also post about this on the beaglelogic google group:
https://groups.google.com/forum/#!forum/beaglelogic

thanks,
drew

3

Hello,

did you make any progress or anything to share? I use the beagle-logic on the BBB, but it could be interesting on the PB too. Any website/blog or git?

cheers

4

All,

BeagleLogic, the software, will run on the PocketBeagle for sure, but the pins will be limited as only a very limited number of PRU1 pins (the pins marked pr1_pru_r31_xx) are broken out on the expansion headers. The way BeagleLogic works is that PRU1 samples the pins while PRU0 writes samples to RAM. Therefore the R31 of the PRU1 is the one it can read. Theoretically if one can tweak the firmware and the kernel driver, one could get it to sample the PRU0 pins instead, so you could have the PRU0 pins available.

I have designed a board prototype that converts the BeagleLogic to a standalone logic analyzer - https://theembeddedkitchen.net/announcing-beaglelogic-standalone/694 but is not released yet, although I do hope to make it available for sale in the near future. There’s a link you can sign up to on the blog page, and I’ll send you updates as and when it happens.

Thanks
Kumar Abhishek

5

Thanks for the info. That explains a lot. However, I see in the system reference manual for the pocket there are eight pr1_pru1_pru_r31_xxx pins. Any idea why only 4 were working in my test? Sounds like PRU1 should be able to see 8.

https://github.com/beagleboard/pocketbeagle/wiki/System-Reference-Manual#67_PRUICSS

6

from an overall cost perspective, for hobby needs, it would be great if a Pocketbeagle could be made that connects via USB to a host computer and does like a six/eight channel capture. At 25 dollars for a pocket beagle, even if adding a cape for voltage protection, that seems like it would well less then a board based on the full fledge BeagleBone black (with ethernet, etc). So if there a tweaks that could be made, it would a real advantage.

Charles