I've found some separate instructions for connecting an SD reader/writer and also instructions for connecting a RFID reader and Piezo Buzzer. I would like to use both modules and the piezo buzzer together on the same Arduino. See below for the pin wiring details from each instruction I found:

SD Reader/Writer

  • 3.3v goes to 3.3v on the Arduino UNO (for power)
  • GND goes to Ground on Arduino UNO
  • D0 goes to pin 12 on Arduino UNO
  • D1 goes to pin 11 on Arduino UNO
  • CLK goes to pin 13 on Arduino UNO
  • D3 goes to pin 10 on Arduino UNO

RFID Reader

  • SDA - Digital 10
  • SCK - Digital 13
  • MOSI - Digital 11
  • MISO - Digital 12
  • IRQ - unconnected
  • GND - GND
  • RST - Digital 9
  • 3.3V - 3.3V

Piezo Buzzer

  • Red - Pin 8
  • Black - GND

Is using the same pin for more that one module ok?

  • What RFID reader do you have / what interface does it use? SPI?
    – chrisl
    Dec 14, 2018 at 22:09
  • (1) I'm currently using this RFID reader, but I'm going to change to ID-20LA which has a better range (2) I'm thinking of buying this SD module
    – Chris Snow
    Dec 15, 2018 at 7:29

1 Answer 1


pins 11 MOSI, 12 MISO and 13 SCK are SPI bus. You can connect more devices to the bus. A 'slave select' ('cable select') pin determines which device will communicate. In your table both devices use pin 10 for this. You must change one.

I recommend to wire SD reader D3 to pin 4 and in sketch use SD.begin(4).

Note: some cheap SD card adapters block other devices on the bus and can be used only as single device on the bus

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.