Adafruit launched it's PiTFT not long ago and I bought one immediately from Pimoroni. Soon after that Adafruit published a tutorial entitled DIY WiFi Raspberry Pi Touchscreen Camera. I had a good read through it and on the final page the final paragraph was;
The package could be slimmed down considerably; there’s a huge amount of empty space between the PiTFT and Raspberry Pi (even more with a Model A board). Advanced makers could squeeze a slim LiPo battery and a 5V boost converter in there, connecting to the expansion header at the right edge of the TFT board instead of the side-protruding USB power connector. The result would be similar in size to some consumer point-and-shoot digital cameras.
Hmmm OK, Challenge Accepted!
But let's see if we can fit in a charger too, and attach some lenses while we're at it. Modern cameras feature both as standard, no reason why the SnapPiCam shouldn't......
Thanks for voting for the SnapPiCam in the Raspberry Pi Contest, we made First Prize!
The SnapPiCam kit is available from The LittleBox Company.
Step 1: Parts
1 x Raspberry Pi Camera
1 x Adadfruit PiTFT
1 x Adafruit LiPo Charger
1 x Adafruit 1200mAh LiPo
1 x Pololu Step-Up/Step-Down DC Converter
1 x Slide Switch
1 x Compact Micro SD Adaptor
1 x 8gb Micro SD Card
4 x M3 45mm Button Head Screws
4 x M2 8mm Screws
8 x M2 6mm Screws
2 x Nylon M2.5 6mm Screws
2 x M3 4mm Nylon Spacers
4 x M3 Microbabrs
2 x M2.5 Microbarbs
12 x M2 Microbarbs
25 x Laser-Cut Acrylic Parts
1 x Raspberry Pi Mini Sticker
1 x 8x Zoom Lens
1 x Fish-Eye Lens
1 x Telephoto Lens
Step 2: Power
Before I started with the build I hooked up the electricals to a DC Power Supply. By doing a few calculations using the data from the DC Supply we can work out an estimated run-time.
To calculate the power consumption of the electrical components in watts we multiply Volts by Amps.
V x A = W
5.2 x 0.51 = 2.652
The electricals consume power at 2.652 watts per hour. Next we calaulate the battery's capacity.
V x A = W
3.7 x 1.2 = 4.44
The battery holds 4.44 watts based on 3.7v. The Lipo will supply ~4.2v when fully charged, and it's lowest rating is 3.7v. I've gone with the lower value as not to over-estimate the run-time.
Now we know the battery's power capacity and the electricals consumption rate we can approximate the run-time with a simple division.
4.44 / 2.652 = 1.674
We can expect a run-time of 1.6 hours, or 96 minutes. An hour and a half.
Step 3: Starting Point
I began by taking measurements of the Raspberry Pi. From that I could estimate the overall width and height of the camera frame. I wanted all the ports such as HDMI, USB and the SD Card all to be accessible even with the components fully enclosed. I also left space for a screw in each corner.
The overall width of the camera worked out at 101mm and with height was 67mm. The depth of the camera depends on how many layers of 3mm acrylic it would take to enclose everything in.
Next I needed to model the LiPo Charger and the DC DC Converter as both of those would be going at the front. The PiTFT needs to face backwards so the Raspberry Pi will be in a down-position with the camera and charger in front.
Cut-outs in the acrylic layers will hold the components. I'll also use recessed Microbarb brass inserts as bolt anchor.
I want to attach some lenses to the front. I bough a few different ones off eBay. The small ones are magnetic and need a washer to attached themselves, but the 8x Zoom has a latching system. I'll have to use interchangeable lenses to handle the two types.
The battery is ~5.5mm thick. It should fit nicely between two 3mm layers. I'll make cut-outs for the battery in the layers and add thinner layer each side of those to box the battery in.
There will also need to be holes for the GPIO and channels for the wires and cables. I'll also need an On / Off switch.
Step 4: Putting it together
I went through several versions before arriving at the final design. Before connecting all the wiring I did a test build to make sure it all fitted together.
I've used Microbarb brass inserts instead of nuts. They are a super bit of engineering. Some of the holes for the inserts have been engraved so the Microbarbs will sit flush with the acrylic so the layers will be flat togeher.
Step 5: Wiring
I had to remove the wires from the LiPo to make it easier to assemble. The FFC for the camera needs to be bent at some nastey angles. You can really only bend the cable once, after that the tracks will probably break and then it will need replacing. You can use the standard cable that comes with the camera.
Two pins connect to the PiTFT on pin 2 (+5v) and pin 9 (GND). Before you connect them to the power check the volatages are correct. You'll find the DC DC Converter needs adjusting. I set mine at 5.2v.
Step 6: Power Up
A neat trick If you have setup a DropBox account on the camera is using your phone as a Wi-Fi hot-spot to upload your photos to DropBox even while out and about. It makes transfering images back from the camera so much easier.
The LiPo can be set for different charge rates, I left mine as is at 500mAh, most PC USB ports won't give out much more than 500mAh anyway. I didn't want to overheat the battery while it's in an enclosed space either. Charge time is about 3 hours.
Step 7: The Results
In what can be described as a typically windy British Day in Derby I ventured out to take a few test shots. The Photos are as follows;
1 | No lens
2 | Fish-Eye
3 | 2 x Telephoto
4 - 7 | 8 x Zoom Lens
8 | Fish-Eye Selfie.
All the photos are unedited.
There are several change I want to make to the design when I get the time; the process of swapping between the magnetic lenses and the 8 x zoom lens is way too complicated to do outside. I'll change the four M2 screw for a single M3 Thumb Screw and have knotches to stop it from rotating. I'll also consider using black acrylic for the lens assembly to stop any light seaping into the picture like what can be seen on the photos taken with the 8 x z00m lens. There is room to the left of the AV socket to fit in a tripod mount, I ran out of time but it will be featured in any future versions. Finally the three polycarbonate sheets, the two for the battery enclose and the back-plate, will be swapped out for 1mm acrylic.
A set of the SnapPiCam plans can be downloaded for free from The LittleBox Company