Raspberry Pi Board Components: Ports, Connectors, and GPIO
Identify the main Raspberry Pi Model B+ board components, including the SoC, GPIO, HDMI, USB, Ethernet, audio, power, camera, DSI, and microSD connectors.
A Raspberry Pi is a single-board computer: a complete computer built primarily on one circuit board. Unlike a laptop or desktop computer, many of its connectors, chips, and pin headers are exposed so you can connect peripherals and electronic circuits directly.
The board is approximately 85.60 mm × 56 mm × 21 mm, or about 3.37 × 2.20 × 0.83 inches. A case can protect the board from dust, accidental contact, and short circuits. However, an uncovered board makes the components easier to see while you learn.
Model B and Model B+ at a glance
The Raspberry Pi Model B has a 26-pin GPIO header and 2 USB ports. The Raspberry Pi Model B+ has a 40-pin GPIO header and 4 USB ports. The boards also differ in the physical placement of some ports and connectors.
| Feature | Raspberry Pi Model B | Raspberry Pi Model B+ | Why the difference matters |
|---|---|---|---|
| GPIO header pin count | 26 pins | 40 pins | GPIO instructions and wiring diagrams must match the board model. |
| USB port count | 2 ports | 4 ports | The number of keyboards, mice, storage devices, or other USB peripherals you can attach directly differs. |
| Component and connector placement | Different layout | Different layout | Do not identify a connector by position alone; compare the board markings and model. |
The system on a chip
A SoC, or System on a Chip, is an integrated circuit that combines several important computer functions. On the Model B+ example, the SoC provides the main processing and graphics capabilities and works with the board's memory resources.
The Model B+ example uses an ARM1176 processor running at 700 MHz, graphics processing capability, and 512 MB of RAM.
- CPU: The Central Processing Unit executes program instructions and performs general-purpose calculations.
- GPU: The Graphics Processing Unit handles graphics and video-related work. It contributes to high-definition video output.
- RAM: Random Access Memory is temporary working memory used by the operating system and running programs. RAM is not the same as removable storage.
The large main chip is commonly identified as the SoC. RAM is a separate memory resource on the board, while the CPU and GPU are functions provided by the computing system's main chip.
Storage: the microSD card slot
The microSD card slot holds the removable flash-storage card used for the Raspberry Pi operating system, programs, and files. The card is the board's boot media in this class of Raspberry Pi.
On the Model B+ layout, the slot may be on the underside or opposite side of the board from the main connectors. Turn the board over if you cannot find it. Do not confuse the microSD slot with the narrow ribbon-cable connectors.
A microSD card is removable storage. It is different from the 512 MB of onboard RAM: the card keeps data when the power is removed, while RAM is temporary working space used while the Pi runs.
For related setup steps, see formatting an SD card and installing the Raspberry Pi operating system.
Display connections
HDMI
The HDMI, or High-Definition Multimedia Interface, port connects the Raspberry Pi to a conventional monitor or television. HDMI can carry both digital video and audio through one cable.
DSI
The DSI, or Display Serial Interface, connector is a ribbon-cable connector for a compatible LCD display panel. It is intended for a dedicated display connected directly to the board.
| Connection | Purpose | Example device | Key distinction |
|---|---|---|---|
| HDMI | Digital video and audio output | Monitor or television | Uses a standard HDMI cable for a conventional display. |
| DSI | Display connection | Compatible LCD panel | Uses a dedicated ribbon connection rather than a normal monitor cable. |
| Camera connector | Camera input | Compatible Raspberry Pi camera module | Designed for the camera interface, not for a display. |
| USB | Peripheral connection | Keyboard, mouse, or USB camera | General-purpose peripheral interface; a USB camera is different from a camera-module connection. |
| 3.5 mm audio | Analog audio output | Headphones or speakers | Audio-only connector. |
GPIO header
GPIO means General-Purpose Input/Output. GPIO pins allow the Raspberry Pi to read signals from external electronics and send signals to them. Beginners commonly use GPIO with buttons, LEDs, sensors, and other small circuits.
GPIO header pins can have different roles:
- Input: reads a signal, such as a button or sensor state.
- Output: sends a signal, such as controlling an LED through suitable circuitry.
- Power: supplies a designated voltage to compatible circuits.
- Ground: provides the electrical reference and return path for a circuit.
Not all pins are interchangeable. The Model B has 26 header pins, while the Model B+ has 40. Always verify the pin numbering and functions for the exact board before wiring anything.
Networking and USB connectivity
Ethernet
The Ethernet port provides a wired network connection to a router or local network. The Model B+ example supports standard 10/100 Mbit/s Ethernet.
USB
USB 2.0 ports connect peripherals such as keyboards, mice, USB storage devices, and other compatible equipment. The Model B has two USB ports; the Model B+ has four.
A dedicated USB/Ethernet interface chip acts as the controller supporting the USB and Ethernet connections. It is a smaller chip near those external ports, separate from the main SoC.
Audio connection
The 3.5 mm audio jack provides an analog audio connection for headphones or speakers. It is separate from the HDMI connector, although HDMI can carry audio digitally to a compatible monitor or television.
Power input
The referenced Model B+ board uses a micro-USB power connector. This connector supplies power to the Raspberry Pi.
Use a suitable power supply designed for the board. Do not attempt to power the Pi through unintended GPIO, USB, or other connections unless a circuit has been specifically designed for that purpose. Incorrect power connections can damage the board or connected components.
Camera connection
The camera connector is a dedicated ribbon-cable connector for a compatible Raspberry Pi camera module. A camera module can be used to take still images and record video.
This is different from using a USB camera. A USB camera connects to one of the USB ports as a general USB peripheral, while a camera module uses the dedicated camera connector.
See the related guides for enabling the camera and recording pictures and videos.
Raspberry Pi Model B+ board component guide
| Component | Location or appearance | Primary purpose | Typical connected device or function |
|---|---|---|---|
| SoC | Large main chip on the board | Provides the main computing and graphics functions | CPU processing, GPU graphics, and video work |
| DSI display connector | Narrow ribbon-cable connector | Connects a compatible LCD panel | Dedicated Raspberry Pi display |
| MicroSD card slot | On the underside or opposite side of the board | Holds operating-system and file storage | Removable microSD card |
| GPIO header | Long row of exposed pins | Connects to external electronic circuits | LEDs, buttons, sensors, power, and ground |
| HDMI port | Digital video connector on the board edge | Outputs video and audio | Monitor or television |
| Ethernet port | Network socket on the board edge | Provides wired networking | Router or network switch |
| USB ports | Four USB sockets on the Model B+ example | Connects USB peripherals | Keyboard, mouse, storage, or USB camera |
| 3.5 mm audio jack | Small round audio socket | Provides analog audio output | Headphones or speakers |
| Micro-USB power connector | Small power socket on the board edge | Supplies board power | Suitable micro-USB power supply |
| USB/Ethernet interface chip | Smaller chip near the USB and Ethernet connectors | Controls the USB and Ethernet interfaces | USB peripherals and wired networking |
| Camera connector | Narrow ribbon-cable connector | Connects a compatible camera module | Still-image and video camera module |
First board-identification walkthrough
- Place the board on a non-conductive surface and identify the model marking. Use a Model B+ layout only when the board is actually a Model B+.
- Find the large SoC, usually the most prominent chip on the board. This is the main processing and graphics chip.
- Locate the DSI display connector, a narrow ribbon connector intended for a compatible LCD panel.
- Turn the board over and find the microSD card slot. This is where the operating-system card is installed.
- Find the long 40-pin GPIO header on the Model B+. A Model B has a 26-pin header instead.
- Trace the board edge to identify the HDMI port for a monitor or television.
- Identify the Ethernet port, then the four USB ports on the Model B+ example.
- Find the 3.5 mm audio jack for speakers or headphones.
- Locate the micro-USB power connector. This is the designated power input for the referenced board.
- Find the USB/Ethernet interface chip near the USB and Ethernet connectors.
- Locate the camera connector, another narrow ribbon connector, before attaching a compatible camera module.
- Compare the markings and connector arrangement on your actual board before inserting a card, cable, accessory, or GPIO wire.
Example: a basic desktop-style setup
A simple setup combines several board components:
- Install the operating system on a microSD card and insert it into the microSD slot.
- Connect the HDMI port to a monitor or television.
- Connect a keyboard and mouse to the USB ports.
- Connect Ethernet to a router if wired networking is needed.
- Apply power through the micro-USB power connector using a suitable supply.
In this arrangement, the microSD card provides storage, HDMI provides the display connection, USB provides input devices, Ethernet provides networking, and the power connector supplies energy to the board.
Choosing the right connection
- Choose HDMI for a conventional monitor or television and for video plus audio over one cable.
- Choose DSI for a compatible dedicated LCD panel.
- Choose the camera connector for a compatible Raspberry Pi camera module.
- Choose USB for a USB camera or other USB peripheral.
- Choose the 3.5 mm audio jack for analog headphones or speakers.
Troubleshooting component identification
The operating-system storage slot is missing
The microSD slot may be on the opposite side or underside of the board. Turn the board over and look for the card-shaped slot. Do not mistake a ribbon connector for the storage slot.
A USB accessory does not fit, or fewer ports are available
Check the board model. A Model B has two USB ports, while a Model B+ has four. Instructions showing four ports may be describing a Model B+ rather than a Model B.
A connected display shows no image
Check whether the display is a conventional monitor or television, or a compatible LCD panel. Use HDMI for the former and DSI for the latter. HDMI and DSI are not interchangeable display connections.
A GPIO circuit does not work or may damage the board
Disconnect power and review the model-specific pin layout. Incorrect pin identification, unsuitable voltage, and short circuits are common hazards. Confirm power, ground, and signal pins before reconnecting the circuit.
The Raspberry Pi does not start
Confirm that a suitable supply is connected to the micro-USB power input on the referenced model. Also check that a prepared microSD card is installed in the correct slot.
Key points to remember
- The Raspberry Pi is a compact single-board computer with exposed hardware connections.
- The Model B has 26 GPIO pins and 2 USB ports; the Model B+ has 40 GPIO pins and 4 USB ports.
- The SoC provides CPU and GPU functions, while RAM supplies temporary working memory.
- The microSD card stores the operating system and files; it is not RAM.
- HDMI connects to a conventional monitor or television, while DSI connects to a compatible LCD panel.
- GPIO wiring requires correct pin identification, suitable voltage levels, and protection from short circuits.
- Always compare your board's model markings and connector arrangement before following a hardware guide.