Box for RFID DOMINATOR 2.0
In May 2023, the design of the PCB (printed circuit board) for the RFID DOMINATOR 2.0 stopwatch, which is intended mainly for Airsoft or Paintball games with the DOMINATION game mode, saw the light of day. Subsequently, in August 2023, physical PCB samples from JLCPCB were also released. It was an upgrade of the original version 1.0, which fixed several errors. In addition to the functionalities of the older version 1.0, the new PCB slightly offset the RFID reader, which with its module touched the LCD 2004A display module. However, there are several significant changes in the new version, namely access to the I2C converter potentiometer for controlling the contrast of the LCD character display even during the game without the need to disassemble the LCD display.
This was a critical error, as the LCD display set for the summer months had a problem in the winter and vice versa, and the constant removal of hardware was annoying. The display was not readable with the preset contrast for a different season. Also, with the hardware disconnected, it was not possible to see the change immediately, so the display had to be disconnected and reconnected several times until the appropriate contrast was set. This was definitely not a suitable thing to solve in the middle of a game.
The newer PCB also offers the possibility of programmatic implementation of the DOMINATION game mode for up to 4 teams simultaneously and, depending on the firmware, it also allows operation for standard 2, 3-team versions in terms of software (the excess LEDs are simply not used and do not even have to be mounted on the PCB). The Arduino Nano controller with AVR ATmega328P, the 2004A display, the RC522 RFID reader, and the buzzer with a 7.62 mm pitch have remained unchanged. LEDs with a diameter of 5 mm are still used. The resistor values have been adjusted to achieve approximately the same luminous intensity for all LEDs.
Virtually any application can now be built on the working hardware. In addition to the standard DOMINATION mode, which calculates times for all teams from zero to practically 99 hours, 59 minutes and 59 seconds, it is possible to implement the opposite game mode in the future, namely COUNTDOWN, or other forms of game modes, e.g. with only one time. Support for AT commands for the device is also in preparation, through which it will be possible to obtain information about the device configuration and the possibility of configuring functionalities, e.g. the game mode with which the device will start, while more than one can be stored in the device.
Also the possibility of disabling the buzzer in the game, setting its frequency at which it emits sound, etc. Also the possibility of displaying and editing system data with export in one step, if the user requires identical functionality on another device, then in short, Copy-Paste style, he configures a new device to which he ported the firmware with identical functionality also in terms of system settings, which are stored in the EEPROM memory. The same export can also be saved, for example, in a .txt file for future use.
After more than a year since the PCB was created, the entire Airsoft/Paintball community has finally received a box for the RFID DOMINATOR 2.0! The box was custom-designed for the proportions of the RFID DOMINATOR 2.0. The PCB itself is 104x101 mm with a thickness of 1.6 mm. After adding components and mounting on pin strips, the total thickness of the PCB with components is approximately 45 mm. The entire mounted PCB is mounted on the front wall of the box, and is attached via 4 M3 screws at the corner positions of the LCD character display module.
An additional spacer column above the LCD display module with a height of 6 or 8 mm is used between the display and the box. Depending on the height, the display can be slightly below the edge of the box (8 mm variant), or the box can protrude slightly (6 mm variant). This distance also affects the distance of the RFID reader from the box, but in both cases it works reliably and reads RFID cards, wristbands, or key fobs correctly with the supported ISO/IEC 14443-A standard, which run at 13.56 MHz on contact.
The box has a cutout for a 20x4 (2004A) display, 4 mounting holes for an LCD display. There are 4 more holes for the LEDs, which are their light guides that prevent mutual glare, and there is also a small sound pipe for an active/passive buzzer, which is used to notify the insertion of an RFID card with a change in the game logic. The height of the box also takes into account the ICSP header on the Arduino Nano V3.0, so that it can be conveniently closed.
Since the Arduino Nano is in the center of the PCB, the box contains a section with a reduced profile that allows the power cable with a MiniUSB connector to be fed to the Arduino. The thickness of the box walls is 2 mm. The box width is 124 mm, length 123 mm and depth 46.8 mm with the back cover folded. The box is closed from the back with 4 M3 screws in the corners of the box.
As you can see, the back cover also has a circular cutout, which allows you to continue accessing the potentiometer for controlling the display contrast even during the game, without having to disassemble the case. A screwdriver with a cross-head profile and a diameter of 3 mm is suitable for this. Another improvement of the case is the possibility of using integrated guides for the strap / belt. The strap itself can use a self-retracting buckle, as in my case, but it is also possible to use, for example, a strap with a ratchet.
The cutouts are on the outside of the box and allow the strap to be threaded through even after the box is completely assembled. A 25 mm wide strap is compatible, which allows the device to be temporarily mounted in a non-invasive manner on a tree, fence, beam, or pipe. The strap has a clamp with a pressure spring mechanism, which holds the current position after the strap is pulled, so the DOMINATOR can be mounted anywhere the strap can be pulled.
The same mounting method is also used by, for example, camera traps and trail cameras. The box is made of PLA filament. The device seems really sturdy and I believe it would handle a fall with minimal damage. In addition to the black (plastic) screws that I use, you can also use brass ones, which are often available in this M3 size, but they will shine quite brightly on the box. I use screws with a semi-round head. There is a recess under the screws in the mounting holes on the PCB for the box, so the screws, even with a semi-round head, do not significantly exceed the level of the box line. You can also use a countersunk head for M3 screws to achieve a flat, solid surface.
The box was designed and printed by Mr. Badin. I am very satisfied with his work, everything fully fit my existing hardware for the first time. The gentleman also performed all the necessary measurements on the installed PCB. He performed a test and final print, including 3D modeling of the box. I would definitely use him in the future for box design for other projects. You can find his references on Printables, where you can also contact him if you are interested:
https://www.printables.com/@mbadin_1412087
More about the RFID DOMINATOR project, including the test DEMO firmware, can be found at:
https://martinius96.github.io/Airsoft-DOMINATOR-RFID/
The PCB for RFID DOMINATOR 2.0 can also be used to build other projects. It is possible to put an Ethernet shield ENC28J60 on the Arduino Nano, which scales directly to it, and build any application based on a server or client. Instead of diodes, these GPIOs can be used for inputs or outputs, and any number of I2C devices and sensors can be connected to the I2C port.
