Name: I2C Digital IO Board
Type: Adpater Board
Version: 1.0.0
Author: Dubravko Penezic
Copyright: Creative Commons BY-NC-SA v 3.0
Implemented function:

• PCF8574(A) 8 input ports with or without pull-down resistor
• PCF8574(A) 8 output ports with transistor controlled ground (GND)
• 2x RGB LED 5050 and 2 LED 0805 possible
• Input/output pads available
• Selective input or output mode for all 8 pins
• connectivity for LCD & KYB V 1.0.0 with option to put analogue line instead of INT line to connectivity bus
• selectable I2C address
• selectable pulling resistors for I2C bus

PCB Top image:

PCB Bottom image:

LCD_Keypad_DL_V1_0_0.ino

/*
Author: Dubravko Penezic
 
Version: 1.0, 2012
 
This code is example how to use DpI2CIOPCF8574 library.
 
Source code is provided as is, without any warranty.
 
Distributetd under CC BY v 3.0
 
http://pcb.daince.net/doku.php?id=arduino_code
*/
 
// Library contain Wire.h include, but you need to declare it once again
#include <Wire.h>
 
#include <DpI2CIOPCF8574.h>
 
// set the address to 0x20 - 0x27 for PCF8574
// set the address 0x38 - 0x3F for PCF8574A used on daince I/O Expansion
#define boardAddr 0x38
 
// initialize daince I/O Expansion
 
DpI2CIOPCF8574 io;
 
void setup(void) {
  Serial.begin(9600);
  Serial.println("DpI2CIOPCF8574 V 1.0");
 
  Wire.begin();
  io.begin(boardAddr);
// all pins are output high on begining  
  io.setOutputLow();
 
}
 
void loop(void) {
 
  for(int i = 0; i<8; i++){
   io.setOutputStatus();
   io.toggleOutputPin(i);
   delay(2000);
  }
}

DpI2CIOPCF8574 library you may found here.