Arduino Uno SPI Pin - C Programming Language

Introduction

The Arduino Uno board comes with an ATmega328 microcontroller that supports SPI (Serial Peripheral Interface) protocol. SPI protocol is used to communicate between two or more devices over short distances at high speed.

In this guide, we'll explore how to use the SPI pins on the Arduino Uno board using the C programming language.

SPI Pins

The Arduino Uno board has four pins for SPI communication:

| Pin | Name | Function | | --- | ---- | --------------------| | 11 | MOSI | Master Output Slave Input | | 12 | MISO | Master Input Slave Output | | 13 | SCK | Serial Clock | | 10 | SS | Slave Select |

Basic SPI Communication

The following code example shows how to initialize the SPI communication and send data to a slave device:

#include <SPI.h>

void setup() {
  // initialize SPI communication
  SPI.begin();
  
  // set the SS pin as an output
  pinMode(10, OUTPUT);
  
  // select the slave device
  digitalWrite(10, LOW);
  
  // send data to the slave device
  SPI.transfer(0x55);
  
  // deselect the slave device
  digitalWrite(10, HIGH);
}

void loop() {
  // do nothing
}

In this code, we first include the SPI.h library, which provides the necessary functions to communicate over SPI. We then initialize the SPI communication using the SPI.begin() function.

We set the SS pin as an output and select the slave device by setting the SS pin to LOW. We then send data to the slave device using the SPI.transfer() function. Finally, we deselect the slave device by setting the SS pin to HIGH.

Sending and Receiving Data

The following code example shows how to send and receive data over SPI:

#include <SPI.h>

void setup() {
  // initialize SPI communication
  SPI.begin();
  
  // set the SS pin as an output
  pinMode(10, OUTPUT);
  
  // select the slave device
  digitalWrite(10, LOW);
  
  // send data to the slave device
  SPI.transfer(0x55);
  
  // receive data from the slave device
  byte receivedData = SPI.transfer(0x00);
  
  // deselect the slave device
  digitalWrite(10, HIGH);
  
  // print the received data
  Serial.println(receivedData, HEX);
}

void loop() {
  // do nothing
}

In this code, we first include the SPI.h library and initialize the SPI communication.

We set the SS pin as an output and select the slave device. We then send data to the slave device using the SPI.transfer() function and receive data from the slave device using the same function.

Finally, we deselect the slave device, print the received data to the serial monitor using the Serial.println() function.

Conclusion

In this guide, we've explored how to use the SPI pins on the Arduino Uno board using the C programming language. We've learned how to initialize SPI communication, send and receive data over SPI, and select and deselect a slave device.

By understanding how to use the SPI pins on the Arduino Uno board, you can easily communicate with other devices over short distances at high speed.