After using the Zero Boot System I got thinking of away of making it thinner and more pocketable. I thought I would move the battery from the back of the pi to between the pi and the screen. To do this I thought I could add the power bank board to the same PCB as the screen. Join me below to see how it came out
- 3.5″ waveshare screen clone
- Raspberry pi zero z
- Power bank board
- 1200 mAh
- Pass through headers
- Custom full sized USB PCB
With the old ZBS I had a PCB that attached to the screen and had the long pass through header on it. I came up with the idea of having the power bank board with all the buttons and switches plus a micro USB charger. I also left room for a battery, Which was a challenging since there wasn’t that much space or height to fit it in.
I manged to fit a 1200 mAh battery but I had to remove some of outer packaging and move up the power management board.
The next improvement came with getting rid of the USB hub that also lived on the bottom of the ZBS, This was something I kinda really didn’t want to do since I didn’t want to solder anything to the pi but it was the only way to slim it down.
I made a PCB that would cover the whole bottom of the pi but with a cutout where the GPIO went and extended to accommodate the full sized USB port. I took advantage of the test points on the button of the raspberry pi zero OTG, I put holes where I would normally put POGO pins in the PCB but this time I filled them with solder so it would be soldered to the PI.
The apps are written in pygame, It does take some time to load on the raspberry pi zero but its not all that bad.
The plan for software was for with each add-on I would have a separate SD card that would boot up into the app that would work with it. This would mean I would have to carry a few different SD cards with me. I decided to write an “app switcher” that would load when the pi was turned on, I could then pick the app for what ever add-on I had attached to the pi.
I also added a “hidden” app that would give you some system stats and have an update button, Just hit the app switcher text at the top of the app and wait for it to load. The update button does a “git pull” then if there isn’t any thing to pull down it goes red but if it does pull down changes it goes green, There is a restart button so the changes can take place.
Board files – https://github.com/facelessloser/pocketpi_mk2