MCP23017 I2C 16 input/output port expander

// demo sketch for connecting MCP23017 I2C 16 input/output port expander to Z-Uno

// add library
#include "Wire.h"

//set up channel
ZUNO_SETUP_CHANNELS(ZUNO_SWITCH_MULTILEVEL(getLevel, setLevel));

int levelLeds = 0;
byte dataForLevels[] = { 0x00, 0x01, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff };

void setup() {
  Wire.begin();                             // wake up I2C bus
  Wire.beginTransmission(0x20);             // set I/O pins to outputs
  Wire.write(0x00);                         // IODIRA register
  Wire.write(0x00);                         // set all of port A to outputs
  Wire.endTransmission();
}
 
void loop() {
  // nothing to do
}

// setter functions
void setLevel(byte value) {
  if (value == 255) value = 99;             // on On set max brightness
  levelLeds = value;                        // memorize for getter
  Wire.beginTransmission(0x20);
  Wire.write(0x12);                         // address bank A
  Wire.write(dataForLevels[levelLeds/14]);  // value to send (bit 1 means LED is ON, map to 8 LEDs)
  Wire.endTransmission();
}

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