Raspberry Pi 1 Model A+: A Deep Dive for Makers

The Raspberry Pi 1 Model A+ is a stripped-down, cost-optimized version of the original Raspberry Pi 1 Model B+, released in 2014. It shares the same Broadcom BCM2835 System-on-Chip (SoC) but omits the Ethernet port and USB ports found on its larger sibling, focusing instead on a smaller footprint and lower power consumption. This makes it ideal for projects where space and energy efficiency are paramount, such as battery-powered IoT devices or embedded systems with a single dedicated function.

At its core, the Raspberry Pi 1 Model A+ features the Broadcom BCM2835, a single-core ARM11 processor clocked at 700 MHz. While modest by today's standards, this SoC provided sufficient power for its intended applications at the time of release. It is paired with 256MB of LPDDR2 RAM, which is soldered directly onto the board. This combination allows the Pi to run a lightweight Linux distribution, typically Raspberry Pi OS (formerly Raspbian), enabling a wide range of software development possibilities.

Positioned as an entry-level, low-cost option within the Raspberry Pi family, the Model A+ targeted users who needed the flexibility of GPIO but didn't require network connectivity or multiple USB devices. Its reduced feature set also meant a lower price point, making it an accessible platform for hobbyists, students, and educators looking to explore physical computing and embedded Linux. Unlike the later Raspberry Pi Zero, the Model A+ uses the standard Raspberry Pi header, offering broader compatibility with existing HATs and accessories.

The Model A+ is particularly well-suited for embedded projects that do not require constant network access or extensive peripheral interaction. Its low power draw makes it an excellent candidate for battery-powered sensor nodes, portable data loggers, or custom control interfaces where a full-fledged computer might be overkill. Makers who are comfortable with Linux command-line interfaces and basic scripting will find it a capable platform for creating dedicated, single-purpose devices.

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Specifications

Pinout & pin functions

Wiring & circuit basics

Powering the Raspberry Pi 1 Model A+ is done via its Micro USB port, which accepts a 5V DC input. It is crucial to use a power supply that can provide at least 1A of current to ensure stable operation, especially when connecting peripherals. The board has onboard regulators to step down the 5V input to the 3.3V required by the SoC and GPIO pins. Avoid powering the board directly through the GPIO header's 5V pins unless you are certain of your power source's stability and voltage regulation.

All GPIO pins on the Raspberry Pi 1 Model A+ operate at 3.3V logic levels. This is a critical consideration when interfacing with external components. Connecting a 5V sensor or module directly to a GPIO pin could damage the Raspberry Pi. If you need to interface with 5V logic devices, you must use a level shifter to convert the voltage signals between 3.3V and 5V. Conversely, 3.3V components are generally safe to connect to 5V systems if the 5V system is designed to tolerate 3.3V inputs, but it's always best to check the specifications of both devices.

For a simple LED circuit, connect a standard LED to a GPIO pin (e.g., GPIO17). Connect the longer leg (anode) of the LED to a current-limiting resistor (e.g., 220-330 Ohms) and then to GPIO17. Connect the shorter leg (cathode) of the LED to a GND pin on the Raspberry Pi. When GPIO17 is set to HIGH (3.3V), current will flow through the resistor and LED, illuminating it. When set to LOW (0V), the LED will turn off.

Programming & getting started

The Raspberry Pi 1 Model A+ runs a full Linux operating system, typically Raspberry Pi OS (formerly Raspbian). This means you can program it using a wide variety of languages and tools. For embedded control, Python with libraries like RPi.GPIO or pigpio is very popular and beginner-friendly. You can write Python scripts on the Pi itself or cross-compile them on a more powerful computer. Uploading scripts is as simple as saving them to the Pi's filesystem and running them from the terminal.

For more complex applications or if you prefer a compiled language, C/C++ with the wiringPi library or direct register access can be used. PlatformIO is an excellent choice for managing projects, dependencies, and build environments for C/C++ development on the Pi. You can also use MicroPython or CircuitPython, which provide a Python-like environment optimized for microcontrollers, though performance might be more constrained on the single-core Model A+ compared to newer Pis. The initial setup involves flashing Raspberry Pi OS onto a microSD card and booting the Pi.

Project ideas

Buying tips & gotchas