‘No signal’ during shutdown on Kano touch kit

Hi,
I am getting a ‘No signal’ message on a Kano touch kit during the shutdown process. Error message appears just before the lights turn off.
I have flashed the SD card with a fresh copy of the OS however still getting ‘No signal’ on shutdown. Any help would be appreciated.

Hi @Boshi,

Just to confirm - when you shut down, you get a “no signal” message on screen, and then the screen turns off too?

Likely just a little trickle of power going to the screen after the Pi has entered shut down (and is no longer sending a signal to the screen) - as long as it’s not staying on screen whilst the Pi is off, nothing to worry about.

Hope that helps

Chris

Hi Chris,

Sort of. The system will shutdown and the screen turn off however just before the LED’s at the back turn off the ‘no signal’ message appears for a second and then disappears.

Have you noticed this on other kits?

Just to let you know a replacement battery was sent to me as the original had failed. Could the battery be sending a signal when it shouldn’t?

Regards,

Foshia

Hi Foisha,

I checked with our engineering team, and they confirm that until the main Raspberry Pi board shuts down, there is still power going to the display driver board and screen, even when is no display signal being sent.

So you may get a second or two of the “no signal” message.

Best

Chris

Chris, can you ask engineering if any of the GPIO pins are used by the Touch Kit’s power board?

I understand the power board really only controls the battery and not the Pi itself. That is, holding down the button for 3 seconds at rest simply turns on the battery and screen via the splitter. This behavior is fine.

However after boot, when holding down the power for 10 seconds, does it simply cut power to the battery in the same way?

i.e. does the momentary button on the button send anything to any of the GPIO pins so that KanoOS or any OS that can read GPIO states can issue a proper shutdown?

This would be useful for a situation where the booted OS isn’t accessible via the console interface or remotely from the network.

Thanks in advance.

Hey @KanoGamer,

Just checked in with the engineering team - the GPIO pins are only used to transmit power to the Raspberry Pi board, and one bit of data that tells the Pi if the battery is running out of power.

A redesigned power HAT would be needed for anything more exciting! :wink:

Hope that helps!

Chris

Thanks for the super quick response, Chris!

Regarding that one bit of info where it tells the Pi the battery is low. How and what GPIO pin is it using to transmit that?

Is the a process running in the Kano OS to listen for this message?

If the current power board / hat doesn’t allow for a GPIO pin to be shorted/triggered, the next best alternative is to have a python script to listen for a state change on a GPIO pin from the low battery signal/message and then issue a proper shutdown.

Thanks!