SD card module with Arduino Uno R3

Wiring for the SD card module (full size, SPI) on the Arduino Uno R3 (ATmega328P, 5 V logic), chosen with the same pin rules BoardPilot uses: default buses first, and no pins that are used for flash, USB, the debugger or booting.

Wiring

SD card module pin	Role	Arduino Uno R3 pin	Notes
GND	Ground	GND
3V3	Power	5V	Use 3V3 or 5V, not both
5V	Not wired to the board	not connected	Alternative 5 V input through the on-board regulator
CS	SPI chip select	~10 (PB2)
MOSI	SPI MOSI	~11 (PB3)
SCK	SPI clock	13 (PB5)
MISO	SPI MISO	12 (PB4)
GND2	Ground	GND

Check before you power it on

Supply: 5 V from the 5V pin.

Test code (Arduino)

// Library: SD (built in)
#include <SPI.h>
#include <SD.h>

void setup() {
  Serial.begin(115200);
  if (!SD.begin(10)) {
    Serial.println("No card: check wiring, the card format (FAT32) and power");
    return;
  }
  File f = SD.open("/test.txt", FILE_WRITE);
  f.println("Hello from the board");
  f.close();
  Serial.println("Wrote test.txt");
}

void loop() {}

Arduino board: arduino:avr:uno.

Questions

Which Arduino Uno R3 pins do I use for the SD card module?

GND → GND, 3V3 → 5V, CS → ~10 (PB2), MOSI → ~11 (PB3), SCK → 13 (PB5), MISO → 12 (PB4), GND2 → GND.

Does the SD card module work with the Arduino Uno R3 at 5 V?

Yes: the SD card module runs at 3.3-5 V and the Arduino Uno R3 uses 5 V signals, so no level shifting is needed.

BoardPilot checks this wiring in 3D as you build it, and finds crossed or missing wires on the real board.

Download BoardPilot

Full Arduino Uno R3 pinout · SD card module (full size, SPI): all pins and data

The SD card module on other boards

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