Cant run a basic NFC Code with NFC reader (PN532)

Projects General Guidance
1

Hi folks,

i am using a Arduino Uno R4 wifi together with a PN532 from Elechouse (NFC Module v3)

The NFC Module is set up as I2C: "ON" = up/1, "KE" = down/0.

It is connected as:
PN532 GND to Arduino GND
PN532 VCC to Arduino 3.3V
PN532 SDA to Arduino SDA
PN532 SCL to Arduino SCL

I am using this code:

#include <Wire.h>
#include <PN532_I2C.h>
#include <PN532.h>
#include <NfcAdapter.h>
PN532_I2C pn532_i2c(Wire);
NfcAdapter nfc = NfcAdapter(pn532_i2c);
String tagId = "None";
byte nuidPICC[4];
 
void setup(void) 
{
 Serial.begin(115200);
 Serial.println("System initialized");
 nfc.begin();
}
 
void loop() 
{
 readNFC();
}
 
void readNFC() 
{
 if (nfc.tagPresent())
 {
   NfcTag tag = nfc.read();
   tag.print();
   tagId = tag.getUidString();
 }
 delay(5000);
}

Serial monitor is only showing:
19:17:11.557 -> System initialized
19:17:13.039 -> Didn't find PN53x board

What am i doing wrong here?

3

The Elechouse website has what appears to be a very good user guide for that module. Yet you did not follow it. Could you explain why?

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4

i did it previously with 5v. same result. 3.3v was just a test and i missed to go back to 5v but still same result: Didn't find PN53x board

5

You failed to mention that. That would have been useful information to include up front. Other useful information that would help:

  1. Did you also try an I2C scanner sketch? If you did, what were the results?
  2. Did you examine the module schematic to ensure that it has pullups on the I2C lines? The weak pullups on an Uno are often not enough.
  3. How did you connect to the board? Wires soldered to the board? A header soldered to the board and Dupont connectors to that? Or something else?
6

Thanks so far. I tryed now something different by connecting the SCK, MISO, MOSI, SS, VCC and GND to the Arduino and running it as SPI. Seems to be working. So that case is solved.