The GPIO.setmode(GPIO.BOARD) makes it use pin numbers, but you can use GPIO.setmode(GPIO.BCM) to use GPIO numbers instead.

The DAC/AMP might only provide the first 10 pins on top, but it's not clear from photos if they actually prevent you connecting to the other pins underneath?

Yeah, they do. The DAC covers all 40 pins, while the amp takes the first ten and passes them through to the headers on top of the whole stack. I'm pretty sure it's passing  pins 1 - 10 through as shorting 5 and 6 with the script configured to use them did shut it down. I don't get that if /a/ GPIO pin can be utilised to do a thing, then why couldn't /another/ GPIO be used to do the same thing, providing it's (apparently) unused?

Well yeah, if GPIO is supposed to be general purpose then any unused pin should work.

It seems counter to the point of this to take all pins, only use some, and pass through ones that can't be properly used. What about sending a message to IQaudio seeing if they're willing to help?

Failing that, maybe you can de-solder the connector and replace it with several smaller ones, including a right-angle connector for the unused ports? Or I guess cables would be easier at the expense of compactness.

That's a fair idea, I'll send them a message. There must also be some kind of inbuilt shutdown script, as there's a software power button within the Kodi interface. If I can find that, I might be able to add in the backlight commands, which would be half the battle won.

> There must also be some kind of inbuilt shutdown script

Heh, so yeah, that's a really simple solution - that loser Xen would have pointed it out ages ago if he were here.

You can use systemd to hook into system events (like shutdown), so you can create simple service like this one with Before=shutdown.target:

[Unit]
Description=/etc/rc.local.shutdown Compatibility
Before=shutdown.target

[Service]
ExecStart=/bin/true
ExecStop=/etc/rc.local.shutdown
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

Where /etc/rc.local.shutdown is a script containing the original echo 0 > /sys/class/backlight/rpi_backlight/bl_power (prepended with #!/bin/bash line) and once you've enabled that service, any time the system is shutdown - whether via Kodi or command line or the button - it triggers the script and turns off the backlight.

Okaaaaay... I've created a shutdown file here:
 

/storage/.config/shutdown.sh

And created this script, putting in the backlight command under the poweroff option.
 

case "$1" in
  halt)
    # your commands here
    ;;
  poweroff)
    # your commands here
    ;;
  reboot)
    # your commands here
    ;;
  *)
    # your commands here
    ;;
esac

This works with the software power off, but will mean I need to flick the power switch (which'll be mounted in an under counter cupboard) to get it to turn back on. So, not ideal, but it'll work for now. :)

If I'm understanding what you want to do there is a pin available on the RPi to reset the board/power. Connect a button, press it, and it'll act a soft on type button by resetting the RPi from its shutdown state.

Ah, that'd be damned useful, providing it's somewhere between 1 & 10 and isn't 5!

It's totally separate. It's called "run". Different location on different versions of raspberry pis but the newer ones have it.

Found this which seems useful, I'll have a read before bed:

https://www.raspberrypi.org/forums/viewtopic.php?t=218600
 

That's the one. When you momentarily connect Run to Ground it resets.
On previous models the pin next to Run was also ground, so you could just use those two pins. But on the latest 3B+ (?) the pin next to Run isn't ground, so you need to use a ground on the GPIO header. Which can be any, even if it's used by something else. Ground is ground.

Brilliant. Yeah, the GPIO ground advice is on that site too.

Now I just need a 2 pin header and some soldering skills. :/

It's a doddle. But understandably daunting if you don't solder much. You can probably buy a big bag of headers on ebay for 99p.

Watch a few video tutorials on soldering headers. Bluetack is useful.

Ok, I dug out an old circuit board from a long unused modem and found a set of headers on there that I could remove. I watched a lot of youtube videos on soldering and unsoldering and have discovered that many americans can't pronounce solder. Preferring to leave the 'l' out and making it 'sodder'. :|


Anywho, after a bit of practicing, I unsoldered them, took two out and soldered them onto the Pi. It's not the neatest or straightest, but they're in.

The circuit does work, I've just got to test it now with the whole thing assembled. :)

Edit - Yay, the software switch powers it off and the push switch powers it back on. It's working, but there's room for improvement, but that can all be done later, for now it's something I can give to the builders and say stick this in the wall for me.

I wonder if you can script anything on that Run pin... If that can be used to shutdown/sleep the Pi, that'd be ideal.

Thanks for your help with getting this far PB and Ant. Tonight's job is getting the momentary switch hooked up. It's got 4 poles and didn't come with a wiring diagram, so a little more experimentation is taking place. :)

The kitchen project is continuing, albeit slowly, which is why I've not updated this for a while. If anyone's interested in seeing what it's like let me know and I'll post a link to a google drive file with pictures of how the whole thing's going, but although the Pi is working it won't be installed for a good few days as yet.

I want to see.

Alrighty then. Concept art at the top of the folder, which is what it all should look like by the end of this week. :)

linky
 

Where's the pi thingy?

It's in a box at the moment. The electricians are doing their 2nd fit this week, so it'll go in then. It's going to sit above the work top where they've put a clock on the 3d drawings. There's 3 double power sockets going along there and it'll sit above the middle one. The power leads are going to go to a double socket hidden in the cupboard underneath, so we won't have any cable clutter. The screen and case I've got don't have an easy way of mounting it all into a recess, so I've got a tablet mounting bracket kit; all it contains is 2 small U shaped bits of plastic that screw into the wall and you drop your kit into them.

The screen needs the protection of the case I've got it mounted in, but it's only ~5mm thick, so isn't going to stand out too much. I would have preferred to have it flush in the wall or something like this, but that's hideously expensive for what it is.