martinius96@gmail.com
RFID Domination Timer - stopwatch for Airsoft | Paintball
User entities in a color-coded RFID Domination Timer project:
Team RED
Team GRE
Referee
Eraser
RFID Domination Timer description:
Domination Timer is a device (stopwatch) for Airsoft sports, Paintball with an Arduino microcontroller (Uno / Nano) with an AtMega328P AVR chip. The stopwatch includes an LCD character display measuring 16x2 (16 characters x 2 lines), or 20x4, on which the times of individual teams are displayed. There are 2 teams in the game - RED team and GRE team that play against each other and occupy the imaginary point that is formed by this device - Domination Timer. At the beginning of the game, the display shows the times 00 hours, 00 minutes, 00 seconds for RED team , GRE team . Each member of the team is equipped with a card, bracelet or key fob, which communicates on the frequency 13.56MHz with an RFID reader, if it is within range. Keychains and bracelets can be color-coded (green, red according to team and function ...), which allows them to be distributed more efficiently to players, but also their archiving and storage. If the RED team occupies a point, the team player attaches his card to the reader, thus occupying the point. This action triggers a buzzer that announces a change in the point. Then the RED team's LED at this station will light up and the display will start adding time for that team. If a GRE team occupies a point and a member of that team attaches the card to the reader, a buzzer sounds again, that team's LED lights up, RED's team time is paused, and team time counts. GRE, which occupied the point. If the card / key fob is attached by the organizer (referee), both times are paused until one of the teams inserts the card. This type of card is thus suitable for starting a break, but can also be used at the end of the game, when it is necessary to stop time to evaluate the game. If the card is attached by Eraser, both times are stopped and reset to the initial value of 00 hours, 00 minutes, 00 seconds at the same time. Used to restart the game, initialize a new game. Project RFID Domination Timer for Airsoft is suitable for events, facilities (arenas), or Airsoft teams. Huge advantage of the Domination Timer system is that the system can be cloned using same firmware for multiple RFID Domination Timers, so you can create as many Timers as you want that will react to same cards. The NXP RC522 reader works at a frequency of 13.56MHz, registers RFID tags at approx. 3 centimeters (almost physical contact with the reader is required), compatible ISO / IEC 14443-A tag format. The given tag standard also includes ISIC, bus cards, which function as NFC cards and can communicate their physical address - UID to a reader within range.
LCD 20x4 output for RFID Domination Timer:
Compatible control hardware for RFID Domination Timer:
Arduino Uno
Arduino Nano
AtMega328P - DIP28
AtMega328P - SMD
Peripherals for RFID Domination Timer:
LCD character display 16x2 / 20x4
I2C converter for LCD display
RFID reader NXP RC522
RFID chips of ISO / IEC 14443-A standard
Buzzer
2x LED diodes
How RFID Domination Timer works (hardware side):
The NXP RC522 RFID reader communicates with the microcontroller (Arduino / stand-alone AtMega328P chip) via the SPI bus with a clock signal (CLK) of 4 MHz. The reader responds to the distance of the chip about 3 cm from the antenna, while it has a configurable gain of the antenna in the range of 18 to 48 dB (48 dB is used in the final application). Reads the UID (identifier) of RFID cards in range, forwards this identifier to Arduino. Arduino compares the read card address in a multi-condition, applies digital states to diodes, runs a universal counter controlled by the millis() function, which is responsible for counting both times. Based on the fulfilled condition, the counter will be applied to the given team to which the UID belongs. The time is sent via the I2C bus to the 20x4 character display, where it is plotted on a specific line - only the specific position is overwritten for the fastest possible time recovery. Listing of all adjustments to the display takes up to 30ms at the I2C bus speed of 100 kHz - Standard speed, which is used. In case of serious interest, it is possible to create firmware in machine code for AtMega328P to measure for other types of RFID readers: RDM6300, PN532, Wiegand W26, increase of I2C bus clock signal up to 400 kHz (Fast Speed).
Where to use RFID Domination Timer project:
RFID Domination Timer project is, in terms of its versatility, suitable for implementation in Airsoft actions, and with the possibility of cloning the firmware, it is possible to place X DOMINATOR points in the game field with identical firmware, which players can play with the same RFID cards. DOMINATOR is also suitable for teams, sports grounds and playgrounds, which can use this device to expand the services and game modes offered for different numbers of players. If RFID cards, bracelets or key fobs are color-coded, it is very easy and universally distributed to players based on their team. Their archiving is also simple. Using cards, bracelets or key rings is easy and can handle all ages in Airsoft games. The RFID chip itself is protected in a plastic case, it does not mind dirt, water, it is fully maintenance-free. It has no battery, the chip activates the RFID reader, which charges it with the transmitted electromagnetic field and allows it to send a UID if it is within range of the RFID reader. DOMINATOR is suitable for game modes with the same number of players in both teams, e.g. DOMINATION, Capture Point (Points for multiple cloned DOMINATOR points). It is mainly used for Airsoft sports, Paintball games.
Demonstration of functionality - RFID Domination Timer:
Printed circuit board - (PCB) - RFID Domination Timer - GERBER / production by photo route
PCB production in China
PCBs can be made in Slovakia at PB Spoj , where they can produce double-sided PCBs. Production can be realized, for example, in China, where they can produce double-sided PCBs from GERBER design. One of the most popular and cheapest manufacturers is JLCPCB, where GERBER files can be uploaded directly as a .zip archive. The PCB is visualized, the layers, PCB dimensions, double-sided PCB are set automatically. Production takes 1-2 days. This manufacturer used to be famous for the action of producing 10 pieces of PCBs for $ 2. Today, JLCPCB allows you to produce 5 pieces of this PCB for RFID DOMINATOR for 6.96 €, 10 pieces for 10.16 € (currently as of January 2021, prices are rising). Transport - the cheapest alternative is available for 7.44 € up to DHL with delivery in 3-5 working days, while the cost of transport is 23.16 €. JLCPCB will automatically apply a € 8 discount coupon for shipping, which will be assigned to you after registration. Thus, with the cheapest shipping alternative with delivery within 25 days, this shipping is free with the coupon on the first purchase. An interesting manufacturer of PCBs is also AISLER, which offers PCB production from 3 pieces with a price of about 7.6 € per piece with free shipping, or offers the possibility of delivery for a surcharge via UPS. It is also possible to use other available manufacturers, for example: PCBWay, AllPCB, NextPCB, SeeedStudio, which have the technology for PCB production by machine method from GERBER files.
Pin headers in PCB design:
Spacers in the design PCB:
Part dimensions:
Table connection of terminals - RFID Domination Timer - fully corresponds to the wiring diagram:
| Arduino Uno / Nano (AtMega328P) | NXP RFID RC522 |
| GND | GND |
| 3V3 | 3V3 |
| D9 | RST |
| D10 | SDA (SS) |
| D11 | MOSI |
| D12 | MISO |
| D13 | SCK |
| Arduino Uno / Nano (AtMega328P) | I2C converter for LCD display |
| GND | GND |
| 5V | Vcc |
| A4 (Hardware SDA) | SDA |
| A5 (Hardware SCL) | SCL |
| Arduino Uno / Nano (AtMega328P) | Buzzer |
| GND | GND |
| 5V | Vcc |
| D5 | IN |
| Arduino Uno / Nano (AtMega328P) | LED diodes |
| GND | GND |
| D4 | IN (RED) |
| D3 | IN (GREEN) |
Wiring diagram - RFID Domination Timer:
Program for reading UID addresses of RFID cards for Domination Timer
The program is used to read the identifiers (UID) of RFID tags, cards that will be used in the program for RFID DOMINATOR - this source code does not represent RFID DOMINATOR or its logic! . The UID RFID card is written to the serial (UART) monitor - the used speed is 9600 baud / s (characters per second). The statement should be saved and rewritten in a clear .xls (EXCEL) document, which will facilitate the management of assigned RFID cards to specific teams and entities for the final RFID DOMINATOR application, whose machine code is tied to the supplied UID cards. To successfully upload the source code for loading UID cards, you need to import the MFRC522 library into your Arduino IDE. MFRC522 library in version 1.4.8: Github repository - download the .zip archive and copy the contents of the archive to Arduino / libraries (the folder is most often located in the Documents, or according to your own installation in another location).
Example of stored UID RFID cards - Excel document .xls:
Excel (.xls) template for writing UIDs - Online Google Spreadsheets: 
/*|---------------------------------------------------|*/
/*|Title: Reading UID of RFID cards |*/
/*|Description: Reads via RFID reader RC522 address |*/
/*|of RFID card that is attached and printed |*/
/*|to the UART interface. |*/
/*|The recorded UID cards will be used for DOMINATOR |*/
/*|Author: Bc. Martin Chlebovec |*/
/*|E-mail: martinius96@gmail.com |*/
/*|License: MIT |*/
/*|Revision: 12. Marec 2021 |*/
/*|---------------------------------------------------|*/
// Template - Google SpreadSheet: https://docs.google.com/spreadsheets/d/1EHpdJi8v84eJ-6ExEPT6JuPkxI9Tfbm8v85zGRFvJ1Q/edit?usp=sharing
/*
* Typical pin layout used:
* -----------------------------------------------------------------------------------------
* MFRC522 Arduino Arduino Arduino Arduino Arduino
* Reader/PCD Uno/101 Mega Nano v3 Leonardo/Micro Pro Micro
* Signal Pin Pin Pin Pin Pin Pin
* -----------------------------------------------------------------------------------------
* RST/Reset RST 9 5 D9 RESET/ICSP-5 RST
* SPI SS SDA(SS) 10 53 D10 10 10
* SPI MOSI MOSI 11 / ICSP-4 51 D11 ICSP-4 16
* SPI MISO MISO 12 / ICSP-1 50 D12 ICSP-1 14
* SPI SCK SCK 13 / ICSP-3 52 D13 ICSP-3 15
*
*/
#include <SPI.h>
#include <MFRC522.h>
#define SS_PIN 10
#define RST_PIN 9
MFRC522 rfid(SS_PIN, RST_PIN); // Instance of the class
void setup() {
Serial.begin(9600);
while (!Serial);
SPI.begin();
rfid.PCD_Init(); // Init MFRC522
rfid.PCD_SetAntennaGain(112); // set to max (00001110)
rfid.PCD_DumpVersionToSerial();
}
void loop() {
if (rfid.PICC_IsNewCardPresent() && rfid.PICC_ReadCardSerial()) {
Serial.print(F("Card UID: "));
dump_byte_array(rfid.uid.uidByte, rfid.uid.size);
Serial.println();
Serial.print(F("PICC type: "));
MFRC522::PICC_Type piccType = rfid.PICC_GetType(rfid.uid.sak);
Serial.println(rfid.PICC_GetTypeName(piccType));
rfid.PICC_HaltA();
rfid.PCD_StopCrypto1();
}
}
void dump_byte_array(byte *buffer, byte bufferSize) {
for (byte i = 0; i < bufferSize; i++) {
}
Serial.print("Code of RFID card is: ");
unsigned long kod = 10000 * buffer[4] + 1000 * buffer[3] + 100 * buffer[2] + 10 * buffer[1] + buffer[0]; //finalny kod karty
Serial.println(kod);
}
Program optimization for RFID DOMINATOR:
UID numbers of RFID cards for RED, GRE, Referee and Eraser inserted into fields that can be easily scaled to expand the number of players assigned to a particular group. Entire arrays are stored in the microcontroller's flash memory as row-only segments, so the arrays do not have to run in RAM to take up the RAM used by DOMINATOR. The standard RFID DOMINATOR program for 10x UID for RED and GRE team and 2x UID for Referee and Eraser takes up 9512 bytes of flash memory, i. 30% and 501 bytes of RAM, i. 24%. Static strings (const) of a variable stored in PROGMEM. Used F macro for static reports on the UART monitor or on the LCD character display.
I2C Scanner - a program for reading the address of the I2C converter for the LCD display
Expected output of I2C Scanner:
The Wire library is built into the Arduino IDE, no installation is required. The program can be compiled and verified communication via I2C bus with LCD character display. I2C converter should be connected to Arduino to hardware I2C outlets (SCL to A5, SDA to A4) before loading the program, it is enough even without display. The retrieved display address must be provided for a successful build for Arduino along with the UID of the RFID cards.
#include <Wire.h>
void setup()
{
Wire.begin();
Serial.begin(9600);
while (!Serial); // Leonardo: wait for serial monitor
Serial.println("\nI2C Scanner");
}
void loop()
{
byte error, address;
int nDevices;
Serial.println("Scanning...");
nDevices = 0;
for(address = 1; address < 127; address++ )
{
// The i2c_scanner uses the return value of
// the Write.endTransmisstion to see if
// a device did acknowledge to the address.
Wire.beginTransmission(address);
error = Wire.endTransmission();
if (error == 0)
{
Serial.print("I2C device found at address 0x");
if (address < 16)
Serial.print("0");
Serial.print(address,HEX);
Serial.println(" !");
nDevices++;
}
else if (error==4)
{
Serial.print("Unknown error at address 0x");
if (address < 16)
Serial.print("0");
Serial.println(address,HEX);
}
}
if (nDevices == 0)
Serial.println("No I2C devices found\n");
else
Serial.println("done\n");
delay(5000); // wait 5 seconds for next scan
}