MCP23017

This is another IO expander for your micro controller. I prefer this one to the normal PCF8574 as it has more pins, interrupts and different modes. This model is fairly detailed and dimensionally accurate. The assembly consists of the PCB with the resistors and capacitors being separate as well as the IC. If you want to do the assembly yourself, the IC is positioned with two width mates putting it centered between the two silk layers either side and between the silk layer below and the edge of the PCB. Similarly the row of resistors and capacitors are configured the same being centred with two width mates between the silk layers around each component.