The goal of the project is to study the fundamentals of development for Arduino, the development of technologies for the manufacture of printed circuit boards, the soldering of elements, and the construction of the housing at home. For those who want to repeat or use solutions for their projects, the source code can be downloaded here Github.
The main components of the phone:
- ATmega328P-MU microcontroller;
- GSM module SIM800C;
- Touch TFT display 320×480;
- 3000 mA / h LiPo battery
- Phonebook – 8 numbers;
- SMS messages – 5;
- USSD requests;
- Battery level, GSM signal level, date and time;
- Bluetooth 3.0;
- USB 2.0;
- IDE Arduino – UNO compatibility;
- Games: Breakout, Tetris;
- Case material – beech;
- Dimensions – 120 x 60 x 13.5 mm
The schematic diagram and the printed circuit board are designed in KiCad. An inexpensive CNC3018 CNC milling machine and a set of drills were used to drill the PCB. Metallization of holes in a homemade galvanic bath using copper hypophosphite technology.
Photomasks are printed on a laser printer on the film Lomond Universal Film 0710421.
Apply film photoresist ALPHA 350, illuminate with ultraviolet light, develop and etch with ferric chloride.
Apply a solder mask, illuminate the photomask with ultraviolet light and show the correct recipe.
We cover the contact pads with chemical tin, cut the contour on a milling machine.
It turns out a printed circuit board with an accuracy of 0.1 mm, vias 0.4 mm, the pitch of QFN microcircuits 0.5 mm.
The elements are sealed with HERAEUS F10 solderless solder paste in a conventional household oven with convection.
USB ISP-ASP programmer through the SPI connector is poured into the Arduino bootloader microcontroller.
The result was a “sandwich” – a board, a battery, a display with dimensions no larger than iPhone 5.
The body is made of beech on the same CNC3018 milling machine, along contours with a selection of the KiCad project.
We grind the buttons, the light guide for the LEDs, the hole under the micro USB.
We connect USB to the computer, through the Arduino IDE we upload the BuratinoPhone firmware.
The idea of the sketch. Library Adafruit_FONA with the addition of functions of reading and writing to the SIM card. Library TFT display ILI9488.