Secondary hardware connections

Each of the following connections provides additional interfaces for Raspberry Pi:

• 20 x 2 GPIO pin header (Model A+, B+, 2 B, 3 B, and Pi Zero): This is the main 40-pin GPIO header of Raspberry Pi used for interfacing directly with hardware components. The chapters in this book are also compatible with older models of Raspberry Pi that have a 13 x 2 GPIO pin header.
• P5 8 x 2 GPIO pin header (Model 1 B revision 2.0 only): We do not use this in the book.
• Reset connection: This is present on later models (no pins fitted). A reset is triggered when Pin 1 (reset) and Pin 2 (GND) are connected together. We use this in the A controlled shutdown button concept in Chapter 7, Using Python to Drive Hardware.
• GPU/LAN JTAG: The Joint Test Action Group (JTAG) is a programming and debugging interface used to configure and test processors. These are present on newer models as surface pads. A specialist JTAG device is required to use this interface. We do not use this in the book.
• Direct camera CSI: This connection supports Raspberry Pi Camera Module. Note that the Pi Zero has a smaller CSI connector than the other models, so it requires a different ribbon connector.
• Direct Display DSI: This connection supports a directly connected display, such as a 7-inch 800 x 600 capacitive touch screen.