7seg_vending_machine.ino

#include <SPI.h>

#define PIN_SCK 13
#define PIN_SDI 11
#define PIN_LATCH 10
#define SCROLL_SPEED 10

const byte digits[] PROGMEM = {
  0b10000000,  // 1
  0b01000000,  // 2
  0b00100000,  // 3
  0b00010000,  // 4
  0b00001000,  // 5
  0b00000100,  // 6
};

void setup() {
  randomSeed(analogRead(0));
  pinMode(PIN_LATCH, OUTPUT);
  SPI.begin();
  SPI.setBitOrder(LSBFIRST);
}

void loop() {
  for (int j = 10; j > 0; j--) {
    for (int k = 0; k < 10; k++) {
      for (int i = 0; i < sizeof(digits); i++) {
        digitalWrite(PIN_LATCH, LOW);
        SPI.transfer(pgm_read_byte_near(digits + i));
        digitalWrite(PIN_LATCH, HIGH);
        delay(SCROLL_SPEED * j);
      }
    }
  }

  digitalWrite(PIN_LATCH, LOW);
  SPI.transfer(0);
  digitalWrite(PIN_LATCH, HIGH);
  delay(1000);
}