Mulitiple SPI devices. (NFC Shield v2, and SD shield V2)

Projects Networking, Protocols, and Devices
1

hei, i'm trying to use 2 devices NFC Shield v2, and SD shield V2 at the same time using arduino Uno board. Both modules uses SPI communication, i'm change the ss pin of SD shield to pin7 and the NFC shield still at pin10. i'm combine the NDEF library for NFC shield and SD library, but the result is the NFC shield didn't found. Can anyone help me?

Thx before.

2

Can anyone help me?

Without seeing your code? Without links to your hardware? No.

3

This is the code, i'm trying to read the NFC UID number, and store it to SD Card.
and this is the link to the hardware
http://shieldlist.org/itead-studio/sdcard

#include <SPI.h>
#include <PN532_SPI.h>
#include <PN532.h>
#include <NfcAdapter.h> 
#include <SD.h>

const int chipselect=7;
PN532_SPI pn532spi(SPI, 10);
NfcAdapter nfc = NfcAdapter(pn532spi);

int hold=0;
void setup(void) {
  Serial.begin(9600);
  
  Serial.println("NDEF Reader");
  nfc.begin();
  
}

void loop(void) {
  

nfc.begin();
  if (nfc.tagPresent()==1)
  {
    NfcTag tag = nfc.read();
   // Serial.println(tag.getTagType());
    Serial.print("UID: ");Serial.println(tag.getUidString());

    SD.begin(chipselect);
    File dataFile = SD.open("datalog.txt", FILE_WRITE);
  // if the file is available, write to it:
    if (dataFile) {
                   dataFile.println(tag.getUidString()); 
                   dataFile.close();
                   Serial.println("SAVE SUCCES");delay(100);
                  }  
             else {
                   Serial.println("error opening datalog.txt");
                  }  
  }
  else if(nfc.tagPresent()==0) { Serial.println("Scan a NFC tag\n");}

  delay(1000);
  
}
4

You should disable all other SPI devices before starting any of them. The code below disables the SD card SPI before starting the NDEF reader so the SD card won't corrupt the SPI bus during the startup.

void setup(void) {
  Serial.begin(9600);

  // disable SD before starting NFC
  pinMode(7, OUTPUT);
  digitalWrite(7, HIGH);

  Serial.println("NDEF Reader");
  nfc.begin();
5

i'm trying to disable other SPI devices by put the SS pin to HIGH, but it didn't even work.

The connection is Arduino->NFC->SD.
i try to disconnect the MISO of the SD Shield from the board, and the NFC did work well, but when the MISO pin connected to the board. NFC didn't found.

6

According to the links you posted:
D10 is the SPI slave select for the SD card.
D10 is the SPI slave select for the NFC card.

Did you do a little pin bending and jumpering? Other wise, these two won't work together. They have the same slave select pin.

7

i'm already change the ss pin of the NFC to D9..

and now i'm found that the problem is the NDEF library, when i'm combining with NDEF library it does error. but i try to combining SD library with NFC PN532 original library, it work fine.

But what i want is using NDEF library, and i don't know where's the problem in NDEF library.

8

I would change the SD shield slave select instead. Install the SD card on top of the NFC shield, first bending D10 just enough on the SD shield so it doesn't insert into the NFC shield, then install a jumper wire from D10 to D4.