I've been working on a new project with my raspberry pi 3b+ to turn in into a NFC jukebox/bluetooth speaker and I used the NXP EXPLORE-NFC header to take on the NFC scanning part.

I've connected it using jumper cables so it does't take all 26 ports. It just uses the MOSI, SCK, MISO and one normal GPIO port on the raspberry together with the 5v and grounds.

After installing the nfcrdlib library from the element14 website it seems to work perfectly with the nxppy python wrapper in my python scripts. However, while my OLED screen also works perfectly without the NFC board, as soon as I try them together, all of my I2c addresses seems to be active and my screen stops working. It seems as though the library automatically also initialised all the I2c headers even though none of them are connected and I'm using the board in SPI mode.

Does anyone know if there is a modification we can do in the library to turn this off? Or any other way around it?

Since this board can work both in SPI and I2C mode, I would assume there is a way to use this board in combination with another I2c device as long as I'm using the SPI connection for the NFC board.

Any help or advice is appreciated

  • 1
    It seems as though the library - what library? perhaps you're doing it wrong™ – Jaromanda X Jan 28 '19 at 3:49
  • The nfcrdlib from the element14 website I mention in my post. – Revam Jan 28 '19 at 8:48
  • Sorry. Didn't read very well – Jaromanda X Jan 28 '19 at 9:23
  • It sounds like you have a short to ground on one of the I2C SDA or SCL lines. – joan Jan 29 '19 at 8:40
  • Hi joan, thank for your response. The thing I experience however is that when i connect both the nfc card and the screen there is no issue with the screen. But as soon as I initialize the nfc reader element with the nxppy python wrapper (using nxppy.mifare() ) the screen stops working and the reader is working perfectly. So i assume that the nfcrdlib library (which nxppy uses) is setting some pins to high or low, which makes it so all i2c adresses read active. So I was thinking more software related than hardware. What do you think? – Revam Jan 29 '19 at 11:38

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