Raspberry Pi Zero WH: Tiny Powerhouse for Connected Projects
The Raspberry Pi Zero WH is an ultra-compact, low-cost single-board computer with built-in Wi-Fi and Bluetooth, ideal for embedded projects requiring wireless connectivity.
The Raspberry Pi Zero WH is a stripped-down, incredibly small iteration of the popular Raspberry Pi single-board computer. It retains the core functionality of its predecessors but in a significantly reduced form factor and at a much lower price point. This version, the 'WH', specifically denotes the inclusion of pre-soldered headers (H) and wireless connectivity (W), making it immediately accessible for makers and hobbyists without requiring additional soldering or USB Wi-Fi dongles.
At its heart, the Raspberry Pi Zero WH is powered by the Broadcom BCM2835 system-on-a-chip (SoC). This chip features a single-core 1GHz ARM11 processor, which, while modest by today's standards, is sufficient for many embedded tasks, especially those involving IoT, sensor data logging, or simple control applications. It's important to distinguish the Zero WH from the original Zero and Zero W; the WH adds the convenience of a pre-installed 40-pin GPIO header, which is a significant upgrade for ease of use, especially for beginners.
Positioned as an entry-level, ultra-low-cost option, the Zero WH is perfect for projects where space and power consumption are critical, and where wireless communication is a must. It's an excellent choice for students learning about Linux-based embedded systems, makers building compact IoT devices, or engineers prototyping small-scale wireless sensor networks. Its small size and low power draw make it suitable for battery-powered applications or for integration into tight enclosures where a full-sized Raspberry Pi would be impractical.
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Specifications
| Microcontroller / SoC | Broadcom BCM2835 |
| Architecture | 32-bit ARMv6 |
| Clock speed | 1 GHz |
| Flash / Storage | MicroSD card slot (card not included) |
| RAM / SRAM | 512MB LPDDR2 SDRAM |
| Operating voltage | 3.3V |
| Digital I/O pins | 17 GPIO (General Purpose Input/Output) |
| Analog / ADC | — |
| PWM | Software PWM available on GPIO pins |
| Connectivity | 802.11b/g/n Wi-Fi, Bluetooth 4.1 (BLE) |
| USB | 1x Micro USB OTG port (for data), 1x Micro USB power port |
| Power input | 5V via Micro USB connector (minimum 1.2A recommended) |
| Dimensions | 65mm x 30mm x 5mm |
Pinout & pin functions
| Pin | Function |
|---|---|
| 3V3 | Power output (3.3V) |
| GND | Ground |
| GPIO2 | Data I/O (I2C SDA) |
| GPIO3 | Data I/O (I2C SCL) |
| GPIO4 | Data I/O |
| GPIO17 | Data I/O |
| GPIO18 | Data I/O (PWM0) |
| GPIO27 | Data I/O |
| GPIO22 | Data I/O |
| GPIO5 | Data I/O |
| GPIO6 | Data I/O |
| GPIO12 | Data I/O (PWM0) |
| GPIO13 | Data I/O (PWM1) |
| GPIO19 | Data I/O (PWM0) |
| GPIO16 | Data I/O |
| GPIO26 | Data I/O |
| GPIO7 | Data I/O (SPI MOSI) |
| GND | Ground |
| GPIO8 | Data I/O (SPI MISO) |
| GPIO9 | Data I/O (SPI SCLK) |
| GPIO10 | Data I/O (SPI CS) |
| GPIO11 | Data I/O |
| GND | Ground |
| GPIO14 | Data I/O (UART TX) |
| GPIO15 | Data I/O (UART RX) |
| GND | Ground |
| RUN | System reset (active low) |
| GND | Ground |
| ID_SD | I2C EEPROM data |
| ID_SC | I2C EEPROM clock |
Wiring & circuit basics
Powering the Raspberry Pi Zero WH is straightforward, primarily done through its dedicated Micro USB power port. It requires a stable 5V supply, and a current rating of at least 1.2A is recommended to ensure reliable operation, especially when using peripherals. Avoid using lower-rated power supplies, as this can lead to instability and unexpected shutdowns. The board itself operates at 3.3V logic levels for its GPIO pins. Connecting 5V devices directly to the GPIO pins can damage the Pi Zero WH. Always use level shifters or voltage dividers when interfacing with 5V components.
When connecting external components, always ensure you are using the correct voltage. For example, to blink an LED, connect the LED's anode (longer leg) to a GPIO pin (e.g., GPIO17) through a current-limiting resistor (typically 220-330 ohms). Connect the LED's cathode (shorter leg) to a GND pin. This setup ensures the GPIO pin outputs 3.3V to turn on the LED, and the resistor protects both the LED and the Pi's GPIO.
For more complex sensors like an I2C device (e.g., a BME280 environmental sensor), you'll typically need to connect its VCC to a 3.3V pin on the Pi Zero WH, its GND to a GND pin, its SDA pin to the Pi's GPIO2 (I2C SDA), and its SCL pin to the Pi's GPIO3 (I2C SCL). Always consult the sensor's datasheet for specific wiring instructions and voltage requirements.
Programming & getting started
The Raspberry Pi Zero WH runs Raspberry Pi OS (formerly Raspbian), a Debian-based Linux distribution, making it a full-fledged computer. You can program it using standard Linux tools, scripting languages like Python, or by installing development environments directly on the Pi. For embedded development, Python with libraries like RPi.GPIO or gpiozero is a popular choice for controlling the GPIO pins. You can also use cross-compilation tools on a more powerful computer to build C/C++ applications.
To get started, flash Raspberry Pi OS onto a MicroSD card using a tool like Raspberry Pi Imager. Insert the card into the Pi Zero WH, connect power and a suitable display/keyboard (or set up headless access via SSH over Wi-Fi), and boot up. You can then open a terminal and install necessary libraries or start coding directly. For beginners, using Python with the gpiozero library offers a high-level, easy-to-understand API for interacting with the hardware.