Newbie Questions (which Linux, PRU, eMMC pins...)

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1

I’m a beginner with the BeagleBone Black, but I have significant AVR and C/Linux experience.

I want to use the BBB as an embedded controller, so I won’t be using any video output.
I will want to use:

  • PWM outputs
  • i2c bus
  • analog inputs
  • a 3.3V serial port for PPP
  • few plain digital outputs, no fancy timing.

I would like to run a Java JRE (no flames please!)

I have a few questions:

  • What’s the best Linux distribution to use, given that my main criterion is support for the BBB’s hardware resources?

  • I would like to measure the frequency on some digital inputs, which will be in the range 0-1KHz. I think the best way to do that is via the PRU, using the timer and some interrupts. Is that the best way, and are any of the resources I list above dependent on the PRU (e.g. the PWM) or do they all have dedicated hardware? (I realise that pins are shared – I mean the PRU and its peripherals) (I can also do this using an outboard AVR via i2c, but if the BBB can do it why not…)

  • Are there any other implementations of the BBB hardware? – for instance I’d be interested in one with fewer connectors, the headers not soldered in and/or a smaller form factor.

  • I’m booting off the eMMC. Does that mean that I can’t use any of the MMC1 pins?

Thanks,
Tom

2

I'm a beginner with the BeagleBone Black, but I have significant AVR and
C/Linux experience.

I want to use the BBB as an embedded controller, so I won't be using any
video output.
I will want to use:
- PWM outputs
- i2c bus
- analog inputs
- a 3.3V serial port for PPP
- few plain digital outputs, no fancy timing.
I would like to run a Java JRE (no flames please!)
I have a few questions:

  - What's the best Linux distribution to use, given that my main criterion
is support for the BBB's hardware resources?

It comes with a Linux distribution on it, Angstrom. It has good
support for the hardware resources. If you are already familiar with
another distribution, then use that one. If not, why not stick to the
Angstrom image?

I've downloaded the Oracle JRE and run it on Angstrom several times
without issues.

  - I would like to measure the frequency on some digital inputs, which will
be in the range 0-1KHz. I think the best way to do that is via the PRU,
using the timer and some interrupts. Is that the best way, and are any of
the resources I list above dependent on the PRU (e.g. the PWM) or do they
all have dedicated hardware? (I realise that pins are shared -- I mean the
PRU and its peripherals) (I can also do this using an outboard AVR via i2c,
but if the BBB can do it why not...)

The eCAP hardware on the chip is perfect for this, but I am not aware
of any standard drivers for it as all the existing eCAP drivers I've
seen are only for the PWM function.

There are folks who have used the quadrature encoder successfully, but
I don't think that'll do exactly what you want.

https://groups.google.com/forum/#!topic/beagleboard/0ewLcdUtA_E

Overall, I'd guess that using the PRU would be the simplest method for now.

  - Are there any other implementations of the BBB hardware? -- for instance
I'd be interested in one with fewer connectors, the headers not soldered in
and/or a smaller form factor.

You can contact CircuitCo for customized versions---they've done many.

  - I'm booting off the eMMC. Does that mean that I can't use any of the
MMC1 pins?

Yes.

3

Thanks Jason, that’s very helpful.

Tom