74HC595 SPI 16 shift register

// demo sketch for connecting 74HC595 SPI 16 shift register to Z-Uno

// add library
#include "SPI.h"

ZUNO_SETUP_CHANNELS(ZUNO_SWITCH_MULTILEVEL(getLevel, setLevel));

// pin for RSK
#define RSK 9 

int levelLeds = 0;
byte dataForLevels[] = { 0x00, 0x01, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff };
 
void setup() {
  // wake up SPI 
  SPI.begin();
  // set RSK pin to outputs
  pinMode(RSK, OUTPUT);
  digitalWrite(RSK, LOW);
}
 
void loop() {
  // nothing to do
}

// setter functions
void setLevel(byte value) {
  if (value == 255) value = 99;                                         // on On set max brightness
  levelLeds = value;                                                    // save for getter
  SPISettings spi_settings = SPISettings(8000000, MSBFIRST, SPI_MODE0); // setup SPI
  SPI.beginTransaction(&spi_settings);                                  // Z-Uno specific call of beginTransaction
  digitalWrite(RSK, LOW);                                               // select 74HC595
  delay(10);                                                            // wait for initialization
  SPI.transfer(dataForLevels[levelLeds/14]);                            // write value
  delay(10);                                                            // wait for operation complete
  digitalWrite(RSK, HIGH);                                              // release 74HC595
  SPI.endTransaction();                                                 // stop SPI on pins
}

// getter functions
byte getLevel() {
  return levelLeds;
}