Reset Button

[Romonaga]

Hello,

On the Rasberry Pi boards close to the USB ports they have a place where you can solder a header so you can make a reset button to take the Pi out of hibernation.  This is useful as it can be used to wake up the PI from shutdown -h, without the need to constantly unplug the power supply.

In examining the Tinkerboard I found what appears to be a spot between the HDMI and power port that are unlabeled. In reviewing the schematics it is very unclear what these pads are for.

The pads closest to the edge have about 5 volts coming off of it.  When i short these pads with a wire to simulate a button press it appears the Tinkerboards starts an orderly shutdown.  After it powers off, and I short the pads again the Tinkerboard powers up.

The other 2 pads have just a little over 2 volts coming off and shorting these pads seem to have no affect.

Does anyone know the true use of these pads?

[frankwu100]

Here is my guess after test.

Debian:
Power Btn: hold will "force power off", once trigger "Power" button event

Android: 
Power Btn: hold will show "Power Off" panel, once will "lock screen"
Volume Up Btn: trigger "Volume Up" button

[Romonaga]

Here is my guess after test.

Debian:
Power Btn: hold will "force power off", once trigger "Power" button event

Android: 
Power Btn: hold will show "Power Off" panel, once will "lock screen"
Volume Up Btn: trigger "Volume Up" button

Thank you, my testing validates your findings. I was able to prototype a board that was a able to test the functionality. It also appears that the power off feature performs a clean shutdown of the device. I must say I am very please to see this functionality.

Well this can be done, it requires some code and the use of a GPIO pin. Nice to have this feature directly. Time to send my board designs to fabrication.

[mcerveny]

Beware bad solder joints on switch ground pins that have bad PCB design. There is missing thermal relief (thermal pad) in copper pour ground (see IPC-2221A: Generic Standard on Printed Board Design, Section 9.1.3: Thermal Relief in Conductor Planes).

            

[tonymac32]

I can verify the power button, never tried the other. Good catch on the thermal relief, mcmerveny.

[JGX]

Here is my guess after test.

Debian:
Power Btn: hold will "force power off", once trigger "Power" button event

Android: 
Power Btn: hold will show "Power Off" panel, once will "lock screen"
Volume Up Btn: trigger "Volume Up" button

Hi,

I am currently using the TB under Android OS, which is new for me.

I soldered a momentary switch between HDMI and input.

In my project, I want the TB to monitor some relays through GPIOs.
The main relay will have to be disabled when the switch is pressed for sleep or shutdown.
Till now, I don't really understand the command generated by pressing this switch (under Android) neither the state in which the TB is after pressing the switch.
1- short press seems only to switch off the screen, a kind off lock screen. If you press again the switch the screen lights up. GPIOs' state are not affected.
If you press again the switch too soon, some screen lines are troubled and misaligned

2- longer press but less than 4s pops up the Android power menu. You can then shutdown or reboot the TB. GPIOs are also resetted unless you cancel the window of course.

3- >4s press generates a reset. The displayed screen during reset is horrible

And I am not sure of the exact state of the TB after a short switch action.
If anyone can give me some explanation regarding what this switch does as a command, in particular under Android, I would really appreciate.

[JGX]

Apparently this thread is not followed so much.

HEY ASUS GUYS, DO YOU FOLLOW THE FORUM?
I think that ON/OFF/RESET management is a crucial issue and should deserve some replies from you!!!

Now, I have installed a momentary switch with wires soldered in the PCB's power pads.
Note that solder a 2.54connector in this hole is not easy. Looks like the protection avoids soldering too much.

Config is Android + RPI official 7" touchscreen.
If I press once shortly, it produce lockscreen.
And if I press again less than 20s after, the screen is on again but with a lot of display errors (shifted pixels).
If you wait a bit (around >20s), everything is OK.
Seems that you must wait around 20s between 2 actions on the switch.

Any idea how to avvoid this?

[Edi_veder]

I will have to find a way to make it work for my car headunit project...

I'm worry about the on and off 12v power from acc power source during start sequence of my engine car, maybe a simple capacitor could feed enough power during this moment to get relay open (jumper take off)

[Edi_veder]

I made my test and it's really useless how the board is working or I did't understand.

if the jumper could be drive by a simple relay, it could be so simple with a relay. Getting OS to shutdown is fine, I just have to get the circuit close (jumper on the two pins), but when I open circuit (jumper take off) The OS is not starting.

Can I change this by internal setting???

[Im4Tinker]

If you have the board powered and turned off, when you short the pins again the system will start. Just like a smartphone's power button.