I have a 2 Resistor Voltage Divider with an OPAMP feeding of 4S battery and its output connected to PIJUICE ZEROs battery Jack. (this battery is a Part of a powerbank) This way PI JUICe thinks there is a 1S battery connected to it and can sense how much voltage/percentage is left in the powerbanks 4s battery.
The PIJUICe is powered from the powerbanks USB Socket. PI is connected to PIJUICe using GPIO header, powered through the PIJUICE.
The OPAMP can supply something like 20 mA, so it is good for sensing the voltage and turns out to be enough to power PIJUICE itself (i wonder how much this PIJUICE ZERO consumes) but it is definitely not enough to power the PI through the OPAMP (somebody already tried ?![:)]( "Smile")
) ) so the powerbanks USB socket must be turned on to provide wattage to PIJUICE before trying to turn on the PI.
This whole complicated design is because somebody bought this powerbank to use with a solar panel and PIJUICE ZERO to power PI zero. While i might not like this design, i have to make it work now.
the PIJUICE is configured to turn on the PI every few hours, PI runs for a while and shuts itself down.and stays so until started again by PIJUCE. al least this way it is supposed to work work.
The powerbanks PCB has a button i can solder a wire to. the button has Batteries 15.xx Volts over it,. shorting it toggles powerbanks USB output on and off. I could connect a MOSFET there to toggle the Powerbanks USB Socket On/Off by one of PIJUICES IO PINs.
now i need something like USER FUNCTION on the PIJUICE, to give a pulse to the mosfet, look if PIJUICEs the USB power input has power then turn the PI on or try again or alike.
the same in reverse to switch the PI Off and then the Powerbanks USB Socket (ok this could also be done by the PI because it is already on , but this does not resolve the turn on sequence problem.
Any ideas of the simplest solution?
yes an ATTINY would do (perhaps also replacing the "V-sense" OPAMP after Voltage divider) but also consumes like 15mA and needs own programming.all to complicated. A 555 Timer + perhaps an OPAMP or some logic feedng a follow up System event to PIJUICE after the USB was turned on. to make PIJUICE actually turn on the PI, would also do. but something really simple? i mean we already have an STM running on the PIJUICE and tons on components on its PCB. Even few multicolor LEDs can make any Christmas tree standout. Ii was even considering soldering to a LED and using its flashing pulses to turn on the Powerbank. Am i missing something, and it is much easier to acheive than i think?.
Thank a lot for your Ideas and help!
The PIJUICe is powered from the powerbanks USB Socket. PI is connected to PIJUICe using GPIO header, powered through the PIJUICE.
The OPAMP can supply something like 20 mA, so it is good for sensing the voltage and turns out to be enough to power PIJUICE itself (i wonder how much this PIJUICE ZERO consumes) but it is definitely not enough to power the PI through the OPAMP (somebody already tried ?
) ) so the powerbanks USB socket must be turned on to provide wattage to PIJUICE before trying to turn on the PI.This whole complicated design is because somebody bought this powerbank to use with a solar panel and PIJUICE ZERO to power PI zero. While i might not like this design, i have to make it work now.
the PIJUICE is configured to turn on the PI every few hours, PI runs for a while and shuts itself down.and stays so until started again by PIJUCE. al least this way it is supposed to work work.
The powerbanks PCB has a button i can solder a wire to. the button has Batteries 15.xx Volts over it,. shorting it toggles powerbanks USB output on and off. I could connect a MOSFET there to toggle the Powerbanks USB Socket On/Off by one of PIJUICES IO PINs.
now i need something like USER FUNCTION on the PIJUICE, to give a pulse to the mosfet, look if PIJUICEs the USB power input has power then turn the PI on or try again or alike.
the same in reverse to switch the PI Off and then the Powerbanks USB Socket (ok this could also be done by the PI because it is already on , but this does not resolve the turn on sequence problem.
Any ideas of the simplest solution?
yes an ATTINY would do (perhaps also replacing the "V-sense" OPAMP after Voltage divider) but also consumes like 15mA and needs own programming.all to complicated. A 555 Timer + perhaps an OPAMP or some logic feedng a follow up System event to PIJUICE after the USB was turned on. to make PIJUICE actually turn on the PI, would also do. but something really simple? i mean we already have an STM running on the PIJUICE and tons on components on its PCB. Even few multicolor LEDs can make any Christmas tree standout. Ii was even considering soldering to a LED and using its flashing pulses to turn on the Powerbank. Am i missing something, and it is much easier to acheive than i think?.
Thank a lot for your Ideas and help!
Statistics: Posted by noJuicer — Tue Oct 14, 2025 12:55 am