[Solved] Witty Pi 4 L3V7 auto power on and shutdown

Yes. This is actually a typical use case of Witty Pi 4 L3V7.

You need to turn on the "Auto-On when USB 5V is connected" option, and it is already ON by default.

You also need to set the low voltage threshold to 4.2V or even a little bit higher, so when USB power is off, it will trigger the shutdown.

Hello, thanks. I purchased the witty pi 4 L3V7. However I noticed an issue: if I connect it to a regular usb 3 port on my computer, the pi crashes. I suspect it's because the power draw is too high. I have a 7 inch touch screen connected to it. If I use a wall plug (official pi power supply), it it stable. 

However I really want it to work with the usb port on my computer. Is there a way to use the battery as a support if the power draw is too high? Or can I combine two usb cables into one Y cable to increase the amps? 

Thanks

@anagpo Witty Pi 4 L3V7 always gives higher priority to the USB-C power input, when USB-C is connected, the battery will not be drawn and will be charged instead. Y cable to get higher current from computer may work - Witty Pi 4 L3V7 doesn't limit that because it doesn't know how the 5V comes from, but it will depend on your computer: there is chance that even with two ports can not deliver enough current for your use case.

I have connected the power via the solder terminals on the witty pi, however I only connected V and GND. Would it make a difference if I also connect the data lines? I read something online about usb power negotiation, and I wonder if by connected the data lines I could unlock more current. I also read it may be possible to trick the host by shorting the data lines, but I am not sure.

@anagpo What you read about power negotiation is true, but Witty Pi does not do power negotiation, and the data lines are not connected on Witty Pi board. If you have the interest and skills, you may try those tricks, but still it depends on the implementation of the host - not all hosts accept this. If you are not sure how to do it, then better not to do it -- just to be safe.

Is there no way to use the battery as power while having usb c connected? Unfortunatly the combination of pi zero and hdmi screen draws up to 6W, which is too much, usb 3.0 can only give 4.5W