1. Introduction
Most of us, when we think of spies, do not think of George Koval, the Soviet spy who obtained the most valuable information for Moscow on the Manhattan nuclear project in the United States, or Rudolf Abel, who worked for the USSR, or the famous Mata Hari, who worked for German intelligence, nor about Sydney Reilly, the British spy nicknamed "The King of Espionage." Most of us think about whom? Right. About James Bond - a character created by Ian Fleming, about whom many books have been written and as many films have been shot. By the way, it is believed that the image of Bond was copied from Sydney Reilly in the above list. So that's it. When we think about Bond, we, of course, think about spy gadgets, which, of course, were used by the most real spies. And perhaps the most popular spy gadget is the spy camera.
Therefore, I also wanted to try to build a small camera, based on the small and most popular single-board computer Raspberry Pi Zero W.
2. Concept.
I wanted to assemble a full-fledged mini camera that will work from a battery, capable of recording video with sound and playing it back, and which will have a display and buttons for convenient control. And all this should fit into a small case and be conveniently assembled and disassembled. I chose several modules that I want to place in the case and which were easily accessible to me.
- Raspberry Pi 1.54inch mini LCD touchscreen;
- Raspberry Pi Camera Rev 1.3;
- Microphone INMP441 MEMS;
- TP4056 charging module;
- Module step-up voltage from 3.7v to 5v.
- Audio module PAM8403;
3. Design
I tried to arrange the modules and design the case so that all the buttons and USB holes are at the top or side. I placed the battery and charging modules with a voltage converter on the bottom so that it would be convenient to install them inside. The niche for the battery is closed with a separate lid, so you will not need to completely disassemble the case in order to change it, moreover, this niche will allow you to install a large battery.
4. Hardware
- Raspberry Pi Zero W;
- Raspberry Pi 1.54inch mini LCD touchscreen;
- Raspberry Pi Camera Rev 1.3;
- Microphone INMP441 MEMS;
- TP4056 charging module;
- Module step-up voltage from 3.7v to 5v.
- Audio module PAM8403;
- 10KOhm Potentiometer;
- Power Switch;
- Screws 4pcs. M3x12;
- Screws 4pcs. M3x20;
- Screws 4pcs. M2x7;
- Accumulator 3.7V 1000mA;
Display module
I found such an interesting module with a display and buttons for the Raspberry Pi Zero. It has a 1.54-inch color touchscreen display with a resolution of 480x480, eight buttons and one joystick. The display and sensor work very well, even the smallest letters are readable. Therefore, I will use it for the project.
Very long pins were soldered on this module and the distance between the boards is 2 cm. This option did not suit me very much because I plan to make a compact device. Therefore, I had to unsolder them.
It is best to use PH3.5 2x20P surface mount pins. But I didn’t have these in stock and it took a long time to wait for delivery. Therefore, it was decided to take the usual classic Arduino single-row PH8.5 pins, glue them together, grind them with a file on top of 1.5 mm and bend the legs at 90 degrees. And I got a pin height of 7.5 mm. And I got a pin height of 7.5 mm and a distance between the boards 1 cm. This distance is enough for a cooling radiator if you have to use a Raspberry Pi Zero 2 that heats up as much as 75 degrees.
Pinout of the module.
TP4056 automatically completes the charging cycle when the voltage on it reaches 4.2V and the charge current drops to 1/10 of the programmed value. The module has an indication of the charging process. At the moment of charging, the red LED lights up, and when the battery is fully charged, the green LED lights up, the red one turns off. In addition to the TP4056 charging controller, two chips DW01 (protection circuit) and ML8205A (double MOSFET key) are added to the board, they serve to protect the battery from overdischarge, overcharge, overload and short circuit.
DC-DC module
I used a 3.7v to 5v step-up module. Unfortunately, I did not find any description either for this module or for the F1A9 microcircuit that is installed on it. Module dimensions 24x18mm.
5. Connection
6. 3D Print
Attention. This case is the first trial version in which errors may be present and which will allow me to correct all gaps and holes. Therefore, if you want to print it, consider this. |
I was printing parts with an Ender3 printer. The upper and lower parts of the case and the battery cover were printed with a layer height of 0.2 using supports and with a filling of 20%. The inner part of the case where the on / off button is attached is also only without supports. The buttons were printed with a layer height of 0.1 and 100% infill.
7. Assembly
Attention. Unfortunately, while writing this article, the delivery of some spare parts was delayed (microphone, audio module, potentiometer). As soon as they come to me, I will install them and supplement the article. |
1. Before assembling and slightly processed the edges of the buttons with sandpaper so that they would slide better. Then we put the buttons in our holes.
2. We put the display module and fasten it with screws m3x12 and stands m3x10.
Attention. I found that this module has thin tracks next to the screw hole. Although the board is covered with a solder mask and painted. It seems to me that this is very risky, because if you tighten it tightly, if the rack rotates, you can scratch the board and damage the tracks. Therefore, it is better to use nylon stands or did I just glue a piece of tape and cut a hole in it.
3. It is best to remove the memory card before installing the Raspberry Pi. We insert a 16cm long ribbon cable for the Raspberry Pi camera, bend it at 90 degrees and insert the module into the display.
5. I screwed the Camera module with four screws to the body and connected the ribbon cable.
6. Then I bent the ribbon cable and twisted the two parts of the case with the m3x20 screws. To understand how best to bend the train, I cut off a piece of paper of the same size as the train and bent it. This helped me calculate the curves.
7. Soldered the battery and put it in its place. Closed the lid and screwed it down with four m2x7 screws.
| {gallery} MiniZeroCam |
|---|
IMAGE TITLE: Front |
IMAGE TITLE: Back |
IMAGE TITLE: Front |
IMAGE TITLE: Back |
IMAGE TITLE: Up |
IMAGE TITLE: Switching-on |
8. Software
In order for the image to be displayed on the display and the touchscreen to work, drivers are needed. But the manufacturer already has a prepared original image of the Raspberry Pi OS (Raspberry Pi 1.54inch Game LCD) with built-in drivers on the website, which you just need to download and write to an SD-Card.
When you turn on and configure for the first time, although the display has a touchscreen, you still have to connect at least a keyboard. The first thing I would advise is to go to the terminal and install the on-screen keyboard. Here are the three options I found:
Matchbox-keyboard
sudo apt-get install matchbox-keyboard
sudo apt-get install florence
OnBoard
sudo apt-get install onboard
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