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PiSupply / PiJuice

Resources for PiJuice HAT for Raspberry Pi - use your Pi Anywhere
https://uk.pi-supply.com/collections/pijuice/products/pijuice-portable-power-raspberry-pi
GNU General Public License v3.0
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will PiJuice work with witty3 and PI4? #798

Open pedrosk opened 2 years ago

pedrosk commented 2 years ago

This is a quite newby question.

at the moment I am powering my Pi in the filed from a 12V + Solar panel charger via 5V USB load output. 

[bat] <----> charge controler <---> Solar panel
                                | USB power port
                                v
                            PiJuice
                                v
                               Pi4

This works Ok at the moment accept I am thinking on using the load port on the charge controller and connect like this:

charge controller load port 12V --> witty3 ---> PiJuice with 12000 battery --> PI4

It might be a strange set up. The idea is that I am building a bee monitoring station and may need more than just the bare 2A that the USB port gives. Witty3 can take up to 12V- 28V which would be great! and combined with PiJuice and large backup battery I think I could survive maintenance, changes and bad weather for much longer.

According to the manual on page 38 they use PIN3 GPIO SDA 1, PIN5 GPIO 3 SCL 1, PIN 7 GPIO 7, PIN 11 GPIO 0 and reading PIN8 TXD.

image

The full manual can be found here:

Also would there be a conflict between their RTC and yours? I think using two RTC would be a mess....

For the RTC they say this:

Before installing the software, please check whether you have 1-Wire interface enabled. This is
important because 1-Wire interface uses GPIO-4 by default, which will conflict with Witty Pi. If you
need to use 1-Wire interface, please assign it to a different GPIO pin.
You can assign different GPIO pin to 1-Wire interface in /boot/config.txt file, find the
“dtoverlay=w1-gpio” text and replace it with:
dtoverlay=w1-gpio,gpiopin=18
If you don’t need 1-Wire interface for now, you can disable it:
#dtoverlay=w1-gpio

The only reason I am looking into this solution is 1) PiJuice can NOT use regular 12V input that is in solar applications but HAS excellent UPS properties. Tested a good number solutions and PiJuice is top 2) WITTY 3 runs off solar panel but LACKS the UPS capability.

I am a total newbie and did not power it all together.

I would like to ask is it is safe! I would not want to hurt my PiJuice (I really like it!) Also should Pijuice be on top of the PI4 and have Witty on top or should Witty be on top of the PI4 and Pijuice on top?

Any suggestions are welcome and really appreciated.

Thanks

Ed

tvoverbeek commented 2 years ago

Could work. There is a conflict between the PiJuice RTC and the WittyPi 3 RTC. First connect the PiJuice and the RPi 4 and use the CLI or GUI to change the PiJuice RTC address to e.g. 0x6A (0x68 and 0x69 are used by the WittyPi 3. Also change the EEPROM address to 0x52 so there is no interference of the device tree fragment in the EEPROM. The WittyPi RTC has a higher accuracy than the PiJuice RTC. For the PiJuice it is better to be on top. However the Pi4 might need extra cooling (since it is at the bottom of the stack) dependent on its workload.