constexpr uint8_t RST_PIN = 9; // Configurable, see typical pin layout above
constexpr uint8_t SS_PIN = 10; // Configurable, see typical pin layout above
MFRC522 rfid(SS_PIN, RST_PIN); // Instance of the class
MFRC522::MIFARE_Key key;
// Init array that will store new NUID
byte nuidPICC[4];
void setup() {
Serial.begin(9600);
SPI.begin(); // Init SPI bus
rfid.PCD_Init(); // Init MFRC522
for (byte i = 0; i < 6; i++) {
key.keyByte[i] = 0xFF;
}
Serial.println(F("This code scan the MIFARE Classsic NUID."));
Serial.print(F("Using the following key:"));
printHex(key.keyByte, MFRC522::MF_KEY_SIZE);
}
void loop() {
// Look for new cards
if ( ! rfid.PICC_IsNewCardPresent())
return;
// Verify if the NUID has been readed
if ( ! rfid.PICC_ReadCardSerial())
return;
Serial.print(F("PICC type: "));
MFRC522::PICC_Type piccType = rfid.PICC_GetType(rfid.uid.sak);
Serial.println(rfid.PICC_GetTypeName(piccType));
// Check is the PICC of Classic MIFARE type
if (piccType != MFRC522::PICC_TYPE_MIFARE_MINI &&
piccType != MFRC522::PICC_TYPE_MIFARE_1K &&
piccType != MFRC522::PICC_TYPE_MIFARE_4K) {
Serial.println(F("Your tag is not of type MIFARE Classic."));
return;
}
if (rfid.uid.uidByte[0] != nuidPICC[0] ||
rfid.uid.uidByte[1] != nuidPICC[1] ||
rfid.uid.uidByte[2] != nuidPICC[2] ||
rfid.uid.uidByte[3] != nuidPICC[3] ) {
Serial.println(F("A new card has been detected."));
// Store NUID into nuidPICC array
for (byte i = 0; i < 4; i++) {
nuidPICC[i] = rfid.uid.uidByte[i];
}
Serial.println(F("The NUID tag is:"));
Serial.print(F("In hex: "));
printHex(rfid.uid.uidByte, rfid.uid.size);
Serial.println();
Serial.print(F("In dec: "));
printDec(rfid.uid.uidByte, rfid.uid.size);
Serial.println();
}
else Serial.println(F("Card read previously."));
// Halt PICC
rfid.PICC_HaltA();
// Stop encryption on PCD
rfid.PCD_StopCrypto1();
}
/**
* Helper routine to dump a byte array as hex values to Serial.
*/
void printHex(byte *buffer, byte bufferSize) {
for (byte i = 0; i < bufferSize; i++) {
Serial.print(buffer[i] < 0x10 ? " 0" : " ");
Serial.print(buffer[i], HEX);
}
}
/**
* Helper routine to dump a byte array as dec values to Serial.
*/
void printDec(byte *buffer, byte bufferSize) {
for (byte i = 0; i < bufferSize; i++) {
Serial.print(buffer[i] < 0x10 ? " 0" : " ");
Serial.print(buffer[i], DEC);
}
}
```
---
### Author:  [@glv](https://discourse.processing.org/u/glv)
#### Post date: [September 5, 2021, 8:21pm UTC](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108/2 "2021-09-05T20:21:35Z")
Hello,
Your Processing Code is flashing with this simple test code from Arduino:
```auto
void setup()
{
Serial.begin(9600);
delay(1000);
}
void loop()
{
Serial.println("7320574163");
delay(1000);
Serial.println("21110723902");
delay(1000);
}
```
To get you started:
Most of those `Serial.print()` statements are intended for the Arduino serial monitor for development; only send the required data to Processing for processing.
Do not use the Arduino serial monitor or plotter when making a serial connection to Processing or other software\devices when using a single COM port.
_Edited comment about delay()_
I always add a `delay(1000)` at end of setup() in Processing to allow the Arduino to reset before receiving data. Watch the lights on the Arduino to get familiar with these.
This may not apply to this example.
There are many serial examples in this forum; start simple and build on that.
Reference:
> **[Serial / Libraries](https://processing.org/reference/libraries/serial/index.html)**
>
> Send data between Processing and external hardware through serial communication (RS-232).
`:)`
---
### Author:  [@angoldini01](https://discourse.processing.org/u/angoldini01)
#### Post date: [September 13, 2021, 5:33pm UTC](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108/3 "2021-09-13T17:33:19Z")
Hello,
I added the delay as you requested, but unfortunately I have still the same problem :/.
Would love to hear other tips 😃
Anna
---
### Author:  [@glv](https://discourse.processing.org/u/glv)
#### Post date: [September 13, 2021, 6:07pm UTC](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108/4 "2021-09-13T18:07:35Z")
Hello,
Did the code example I provided for Arduino work with your Processing code?
You should see output similar to what I have.
The delay() was related to this:
> [@Processing to Arduino Serial Library Example](https://discourse.processing.org/t/processing-to-arduino-serial-library-example/11143/5):
>
> I modified the existing “SimpleWrite” example to: save and check for the state of mouseOverRect() print state to console only writes serial data once a delay() to wait for Arduino to reset once connected to it; in my case, it is an Arduino Mega 2560 R3. I kept the spirit of the original example intact and left it as a “Simple Write” program. My edit of “SimpleWrite” example so it only sends data once: /\*\* \* Simple Write. \* \* Check if the mouse is over a rectangle and writes the status …
I edited my last post on this.
`:)`
---
### Author:  [@angoldini01](https://discourse.processing.org/u/angoldini01)
#### Post date: [September 13, 2021, 7:50pm UTC](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108/5 "2021-09-13T19:50:40Z")
Yes I can see the number of the rfid chip in the compiler of processing. But the square is not changing the colors. When I scan the rfid chip the color of the square in processing should change depending on the rfid chip number. Any ideas why that is? 😄 #beingveryhelpful
---
### Author:  [@jafal](https://discourse.processing.org/u/jafal)
#### Post date: [September 13, 2021, 10:53pm UTC](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108/6 "2021-09-13T22:53:48Z")
Hi
Try background in draw function
---
### Author:  [@glv](https://discourse.processing.org/u/glv)
#### Post date: [September 13, 2021, 11:21pm UTC](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108/7 "2021-09-13T23:21:49Z")
Hello,
When I run the Arduino example I provided and your Processing code the rectangle changes color from black to white as expected and repeats every 1000 ms.
Can you share a screen grab of what you are seeing on the serial monitor of the Arduino IDE when you start Arduino and scan a card?
`:)`
---
### Author:  [@angoldini01](https://discourse.processing.org/u/angoldini01)
#### Post date: [September 16, 2021, 8:27am UTC](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108/8 "2021-09-16T08:27:04Z")
I’m glad it works from your side!
Yeah of course,I can send you a screenshot, here is what I see:
---
### Author:  [@angoldini01](https://discourse.processing.org/u/angoldini01)
#### Post date: [September 16, 2021, 8:48am UTC](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108/9 "2021-09-16T08:48:14Z")
I wish it was that easy, but that’s not working neither
---
### Author:  [@angoldini01](https://discourse.processing.org/u/angoldini01)
#### Post date: [September 16, 2021, 9:28am UTC](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108/10 "2021-09-16T09:28:56Z")
Here is one photo with the processing screen on
---
### Author:  [@glv](https://discourse.processing.org/u/glv)
#### Post date: [September 16, 2021, 10:47am UTC](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108/11 "2021-09-16T10:47:13Z")
Hello,
Your Processing code is looking for this:
```auto
if (finalRead.equals("7320574163")) {
state = 1;
}
```
You are sending this:
That is why it is not working.
I previously made this suggestion:
> [@glv](#):
>
> Most of those `Serial.print()` statements are intended for the Arduino serial monitor for development; only send the required data to Processing for processing.
You have to decide what to do:
- Modify your Processing code to look for the String you are sending with the Arduino code you are using as is:
`"data: 49 CD 4A A3"`
- Modify your Arduino code to send a String to match your Processing code.
The data seems to be correct:
The example I provided [here](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108) sends the correctly formatted String data and Processing is receiving it and it working as expected.
I kept it simple as this is your project.
Give this some more thought.
Try to get it working as is.
Clean it up later.
`:)`
---
### Author:  [@angoldini01](https://discourse.processing.org/u/angoldini01)
#### Post date: [September 16, 2021, 1:19pm UTC](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108/12 "2021-09-16T13:19:53Z")
Thank you so so much, it is finally working!!! 😍
---
### Author:  [@RichardDL](https://discourse.processing.org/u/RichardDL)
#### Post date: [September 16, 2021, 1:51pm UTC](https://discourse.processing.org/t/arduino-rfid-and-processing-connection/32108/13 "2021-09-16T13:51:22Z")
I don’t know if your Processing code is using the printed output from that printDec function, but it’s confused. Clearly printHex prints the numbers 0…255 as 2 digit hex values with leading zero where required. printDec is a copy of printHex with HEX changed to DEC, but without rethinking the requirement and logic for leading zeroes. The result is this:
00 01 02 03 04 05 06 07 08 09 010 011 012 013 014 015 16 17 18 19 … 99 100 101 … 255