41. SPI Dice Roll

Build a task, where the SPI Master microcontroller will read data from the slave microcontroller and print it on a serial terminal (e.g., Putty, Arduino IDE).

The Slave microcontroller is a dice roller, which returns any random number between 1 to 6.
The code of Arduino as a slave is given below.

The user will press a push button switch connected to the master microcontroller, and the random number will be read and printed on the Serial terminal.

Remember: Arduino Dice roller uses only SPI Mode 2.

Slave Code (Arduino Dice roller)

#include <SPI.h>

void setup() {
  pinMode(MISO, OUTPUT);  // Set MISO as OUTPUT to send data to the master

  // Enable SPI in slave mode
  SPCR |= _BV(SPE);

  // Send SPI data in mode 2
  SPI.setDataMode(SPI_MODE2);

  // Attach SPI interrupt
  SPI.attachInterrupt();

  // Generate a random number and store it to transmit during SPI communication.
  SPDR = random(1, 7);
}

ISR(SPI_STC_vect) {
  // Generate a random number and send it.
  SPDR = random(1, 7);
}

void loop() {
}