Auto-detection of Raspberry Pi is a PiStack node or not?

[herry13]

Is there any simple way to probe whether a Raspberry Pi is a PiStack node or not? Perhaps by sending a signal through GPIO and evaluate the response.

[herry13]

Currently I use an extra Raspberry Pi as a top-of-the-rack node that controls the PiStack boards through USB-RS232 interface. I think this Pi can do auto-probe by:

1. detecting if there's /dev/ttyUSB[0-9]
2. do C.get_hw_version(0..15) to auto-detect the boards

By doing this, we'll have somekind of plug-n-play capability.

[pjb304]

in stackdaemon.py there is a detect_hat function that checks to see if a hat is detected, if there isn't then it throws an exception. This is done using the EEPROM on the pi stack

[pjb304]

In the latest version of the comms.py there's a search function which will return a tuple of (Number of pi stacks found, [id1, id2...]. Whilst 15 is the highest ID that can be set using the DIP switches, I've now implemented a few commands that enable you to persistently set an id prefix (ie. change the 4 MSBs in the ID), so the max is now 255.

The search command is defined as search(self, start=0, stop=256) so you can specify the min and max IDs that it looks for.

There is now also the commands to tell the pi stack to always power on a specific pi at boot time so the control pi can also be powered from a pi stack board. set_pi_on_startup(self, dev_id, pi_id, status=True)

Hope they do what you are after :)

[pjb304]

For the set_pi_on_startup you'll need to be on pistack firmware v4

[herry13]

Thanks, I'll have a look on detect_hat function. It would be nice if the fruit-monitor can generate a monitoring status that the Raspberry Pi is a PiStack node, and if it does then fruit-config can auto-start the PiStack-daemon.

[herry13]

pistack firmware v4

Is this the firmware that you send to me few days ago?

[pjb304]

That makes sense, feel free to refactor the code if it makes it easier. This was thrown together quickly to test the hardware.

Yes firmware v4 is the one I sent you.