I am attempting to use a Mega2560 with two MFRC522 readers and want to have two possible correct solutions in order to "solve the puzzle" and release a lock. For example, I have 4 RFID tags: A, B, C, D. How do I code so tags A and B on readers 1 and 2 will release the lock, AND tags C and D on readers 1 and 2 also release the lock? I imagine it has something to do with the const String correct IDs, or the solutions is an if statement, not Boolean...but I can't figure it out. Any ideas?
/**
* "Object Placement" Puzzle
*
* This puzzle requires the player to place one or more items in the
* correct location, at which point an RFID tag embedded in the object
* is detected by a sensor.
* When all sensors read the tag of the correct object, the puzzle is solved.
*
* Demonstrates:
* - SPI interface shared between several devices
* - RFID library
*/
// DEFINES
// Provides debugging information over serial connection if defined
#define DEBUG
// LIBRARIES
// Standard SPI library comes bundled with the Arduino IDE
#include <SPI.h>
// Download and install from https://github.com/miguelbalboa/rfid
#include <MFRC522.h>
// CONSTANTS
// The number of RFID readers
const byte numReaders = 2;
// Each reader has a unique Slave Select pin
const byte ssPins[] = {39, 41};
// They'll share the same reset pin
const byte resetPin = 49;
// This pin will be driven LOW to release a lock when puzzle is solved
const byte lockPin = A1;
// The sequence of NFC tag IDs required to solve the puzzle
const String correctIDs[] = {"dd5d21b0", "d8c23b0", "d3823b0", "4d1f22b0"};
// GLOBALS
// Initialise an array of MFRC522 instances representing each reader
MFRC522 mfrc522[numReaders];
// The tag IDs currently detected by each reader
String currentIDs[numReaders];
/**
* Initialisation
*/
void setup() {
#ifdef DEBUG
// Initialise serial communications channel with the PC
Serial.begin(9600);
Serial.println(F("Serial communication started"));
#endif
// Set the lock pin as output and secure the lock
pinMode(lockPin, OUTPUT);
digitalWrite(lockPin, HIGH);
// We set each reader's select pin as HIGH (i.e. disabled), so
// that they don't cause interference on the SPI bus when
// first initialised
for (uint8_t i=0; i<numReaders; i++) {
pinMode(ssPins[i], OUTPUT);
digitalWrite(ssPins[i], HIGH);
}
// Initialise the SPI bus
SPI.begin();
for (uint8_t i=0; i<numReaders; i++) {
// Initialise the reader
// Note that SPI pins on the reader must always be connected to certain
// Arduino pins (on an Uno, MOSI=> pin11, MISO=> pin12, SCK=>pin13)
// The Slave Select (SS) pin and reset pin can be assigned to any pin
mfrc522[i].PCD_Init(ssPins[i], resetPin);
// Set the gain to max - not sure this makes any difference...
// mfrc522[i].PCD_SetAntennaGain(MFRC522::PCD_RxGain::RxGain_max);
#ifdef DEBUG
// Dump some debug information to the serial monitor
Serial.print(F("Reader #"));
Serial.print(i);
Serial.print(F(" initialised on pin "));
Serial.print(String(ssPins[i]));
Serial.print(F(". Antenna strength: "));
Serial.print(mfrc522[i].PCD_GetAntennaGain());
Serial.print(F(". Version : "));
mfrc522[i].PCD_DumpVersionToSerial();
#endif
// Slight delay before activating next reader
delay(100);
}
#ifdef DEBUG
Serial.println(F("--- END SETUP ---"));
#endif
}
/**
* Main loop
*/
void loop() {
// Assume that the puzzle has been solved
boolean puzzleSolved = true;
// Assume that the tags have not changed since last reading
boolean changedValue = false;
// Loop through each reader
for (uint8_t i=0; i<numReaders; i++) {
// Initialise the sensor
mfrc522[i].PCD_Init();
// String to hold the ID detected by each sensor
String readRFID = "";
// If the sensor detects a tag and is able to read it
if(mfrc522[i].PICC_IsNewCardPresent() && mfrc522[i].PICC_ReadCardSerial()) {
// Extract the ID from the tag
readRFID = dump_byte_array(mfrc522[i].uid.uidByte, mfrc522[i].uid.size);
}
// If the current reading is different from the last known reading
if(readRFID != currentIDs[i]){
// Set the flag to show that the puzzle state has changed
changedValue = true;
// Update the stored value for this sensor
currentIDs[i] = readRFID;
}
// If the reading fails to match the correct ID for this sensor
if(currentIDs[i] != correctIDs[i]) {
// The puzzle has not been solved
puzzleSolved = false;
}
// Halt PICC
mfrc522[i].PICC_HaltA();
// Stop encryption on PCD
mfrc522[i].PCD_StopCrypto1();
}
#ifdef DEBUG
// If the changedValue flag has been set, at least one sensor has changed
if(changedValue){
// Dump to serial the current state of all sensors
for (uint8_t i=0; i<numReaders; i++) {
Serial.print(F("Reader #"));
Serial.print(String(i));
Serial.print(F(" on Pin #"));
Serial.print(String((ssPins[i])));
Serial.print(F(" detected tag: "));
Serial.println(currentIDs[i]);
}
Serial.println(F("---"));
}
#endif
// If the puzzleSolved flag is set, all sensors detected the correct ID
if(puzzleSolved){
onSolve();
}
// Add a short delay before next polling sensors
//delay(100);
}
/**
* Called when correct puzzle solution has been entered
*/
void onSolve(){
#ifdef DEBUG
// Print debugging message
Serial.println(F("Puzzle Solved!"));
#endif
// Release the lock
digitalWrite(lockPin, LOW);
delay(500);
exit(0);
}
/**
* Helper function to return a string ID from byte array
*/
String dump_byte_array(byte *buffer, byte bufferSize) {
String read_rfid = "";
for (byte i=0; i<bufferSize; i++) {
read_rfid = read_rfid + String(buffer[i], HEX);
}
return read_rfid;
}