SPI on Arduino UNO: Setup, Wiring, and Your First Sketch

#include <SPI.h>

/*
Pin Description: 
CS  - Chip Select         : Pin-> 10
MOSI- Master Out/Slave In : Pin-> 11
MISO- Master In/Slave Out : Pin-> 12
SCK - Clock Signal        : Pin-> 13
*/

/*
Logic Analyser:
CH0: SCK
CH1: Enable/Chip Select
CH2: MOSI
CH3: MISO
*/


#define CS 10     //Chip Select

char sentValue[] = "SPI Demo: Hello from the Master!";

char receivedValue[255];

void setup() {

  Serial.begin(9600);  //Serial mode is used to check the received value in MISO, in case, the logic analyser is not present.

  pinMode(CS, OUTPUT); //Define the Chip Select Pin to Output (Master --> Slave)
  digitalWrite(CS, HIGH);   // Keep slave deselected, usually teh CS is active low (We need to check the slave datasheet for this information.)

  SPI.begin();

}

void loop() {

  SPI.beginTransaction(SPISettings(100000, MSBFIRST, SPI_MODE2));

  digitalWrite(CS, LOW);          // Select slave

  for (int x = 0; x < strlen(sentValue); x++)
  {
    receivedValue[x] = SPI.transfer(sentValue[x]);
    delay(1);
  }
  

  digitalWrite(CS, HIGH);         // Deselect slave

  SPI.endTransaction();
 
  for (int x = 0; x <37; x++)
  {
    Serial.print("Received: ");
    Serial.println(receivedValue[x], HEX);
  }
  delay(1000);

}