1. J2 J3  Step motor connector J2 (5V,D0,D1,D2,D3)  J3(5V,D4,D5,D6,D7) 

      can use Step motor (28BYJ-48 5VDC)48 5VDC)48 5VDC)48 5VDC)8 5VDC)

2. J20   5V,GND, D0, D1,D2,D3,D4,D5,D6,D7   OUTPUT

3. U5 ULN2803 8 darlington transistor array

4. J17  RS-Pi-V2 GPIO output      

5.  J8  i2c output (GND, 3V3, SDA,SCL)

6. J19  i2c output (GND,5V,SDA,SCL)

7.  JP4 choose 5V input from Mini USB Port J7 or RS-Pi 5V

8. J7  Mini USB 5V input

9. U6 MCP3002 SPI Interface  10 bit Analog-to-Digital Converter 

     output   J11  (Vcc, AD0, GND, AD1)

10. U11 MCP4822 SPI Interface 12 bit Digital-to-Analog Converter   

      output JP1 (DA0,GND,DA1,GND)                          

    U5 2803  use  RS-Pi  pin 11,12,13,15,16,18,22,7 as GPIO 0 to GPIO7

 MCP3002 use 10k ohm Trimpot  for INPUT DEMO 

   MCP4802 OUTPUT  DEMO

You also can use gertboard program atod & dtoa  in this board

   Can work with our RS-Pi-USB Hub Board & I2C 23017 Board