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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 '18 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 '18 at 7:29
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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

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