Communicate 2 PN532 with each other

Projects Programming
1

Hello everybody!

My goal is to send the information of an array of 4736 elements (1byte each element) from one PN532 to another. Is it possible to send that amount of information? I am using an Arduino UNO for each PN532 module.

// Sends a NDEF Message to a Peer
// Requires SPI. Tested with Seeed Studio NFC Shield v2

#include "SPI.h"
#include "PN532_SPI.h"
#include "snep.h"
#include "NdefMessage.h"

PN532_SPI pn532spi(SPI, 10);
SNEP nfc(pn532spi);
uint8_t ndefBuf[128];

void setup() {
    Serial.begin(9600);
    Serial.println("NFC Peer to Peer Example - Send Message");
}

void loop() {
    Serial.println("Send a message to Peer");
    
    NdefMessage message = NdefMessage();
    message.addUriRecord("http://shop.oreilly.com/product/mobile/0636920021193.do");
    //message.addUriRecord("http://arduino.cc");
    //message.addUriRecord("https://github.com/don/NDEF");

    
    int messageSize = message.getEncodedSize();
    if (messageSize > sizeof(ndefBuf)) {
        Serial.println("ndefBuf is too small");
        while (1) {
        }
    }

    message.encode(ndefBuf);
    if (0 >= nfc.write(ndefBuf, messageSize)) {
        Serial.println("Failed");
    } else {
        Serial.println("Success");
    }

    delay(3000);
}

What changes should I make to this code to be able to send the elements of an array? Thank you very much for your help.

2

Theoretically NDEF record payloads are limited in size to 232–1 bytes (the payload length field of the header is four bytes) - of course your Arduino will not support a 4 gigs record, but you should be fine with 4736 bytes.

look at the API for NdefRecord

the type could be TNF_UNKNOWN, which indicates the payload type is unknown but the NFC Forum explains this should be treated similarly to the "application/octet-stream" MIME type.

3

Is there any example where the master sends an array of several elements and the slave receives the data and saves it in another array? I'm new to this and I still don't understand how to do it.

4

explore the examples

(I own only one PN532 so can't play with it the way you want)

5

Okay, thank you.

6

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