Solder a 2x20 male GPIO header to the Raspberry Pi Zero. There will be more soldering in this guide, so if you don't have much experience with soldering, watch this video first:
Start by placing the stacking header onto the Pi Zero, then place four standoffs. Make sure the standoffs you use are the same size as the stacking header.
Put the JuiceBox Zero in place, and fasten to the standoffs down with screws.
Again, refer to the raspberrypi.org video from Step 1 to learn how to solder.
Make sure you use a JST‑compatible, single‑cell lithium‑ion battery.
When you're using a JuiceBox Zero with your Pi, you need to stop using the micro usb port on the Pi. Trying to power the Pi Zero directly could damage the Pi Zero or the JuiceBox Zero. So place a USB cover (or kapton) tape over the USB charging port on the Pi.
Now you're ready to test it out! The JuiceBox Zero comes with a slide switch to power the Pi on or off. Simply slide the switch into the ON position.
Connecting the JuiceBox Zero to a power supply will both power the Pi and charge the battery. This allows your project to run continuously.
The low battery LED will light up when the battery voltage reaches 3.2V. At this time, the GPIO16 pin will go HIGH. So in order to safely shutdown the Pi when the battery is low, we'll run a script in the background that listens for a rising edge on pin 16, then shuts down the Pi.
So first, use your editor to create a new file called
safeshutdown.py in the
/home/pi directory. Add the following:
import os import RPi.GPIO as GPIO GPIO.setmode(GPIO.BCM) shutdown_pin = 16 GPIO.setup(shutdown_pin, GPIO.IN, pull_up_down=GPIO.PUD_DOWN) def shutdown_callback_function( shutdown_pin ): os.system("shutdown -h now") GPIO.add_event_detect( shutdown_pin, GPIO.RISING, callback=shutdown_callback_function, )
Refer to the JuiceBox Zero Github Repository for more details.
Now, edit the crontab by typing the following in a shell:
sudo crontab -e
And add the following to the end of the file:
@reboot python /home/pi/safeshutdown.py &
This will cause the
safeshutdown.py script to run in the background when the system boots. It will listen for a rising edge on pin 16, and then shutdown the Pi safely!