Raspberry Pi 1 Model A: The Original Low-Cost Pioneer

The Raspberry Pi 1 Model A, launched in early 2013, was one of the first iterations of the now-ubiquitous Raspberry Pi single-board computer. Designed to be a more affordable and power-efficient alternative to the original Model B, it stripped away some features like the Ethernet port and an extra USB port, focusing on core computing and GPIO capabilities. This made it an attractive option for hobbyists, students, and educators looking for a low-cost entry into physical computing and embedded Linux development.

At its heart, the Raspberry Pi 1 Model A features the Broadcom BCM2835 System on a Chip (SoC). This chip integrates a single-core ARM11 processor, a VideoCore IV GPU, and various other peripherals. While a single-core processor might seem modest by today's standards, it was sufficient for running a lightweight Linux distribution like Raspberry Pi OS (formerly Raspbian) and handling many embedded tasks. The BCM2835 was a popular choice for low-power embedded devices at the time.

Compared to its sibling, the Raspberry Pi 1 Model B, the Model A has a significantly lower power draw, making it suitable for battery-powered applications. It also lacks the onboard Ethernet port and has only one USB port, which are trade-offs for its reduced cost and power consumption. This board is best suited for makers who are interested in learning Linux, basic programming, and interfacing with the physical world through its GPIO pins, especially in projects where power efficiency is a concern or where network connectivity is not a primary requirement.

The Raspberry Pi 1 Model A represents a significant milestone in making computing and electronics accessible to a wider audience. Its low price point and the extensive community support that grew around the Raspberry Pi platform empowered countless individuals to experiment with hardware and software. It laid the groundwork for future Raspberry Pi models, establishing a legacy of affordability and versatility in the maker community.

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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. A stable 5V power supply capable of delivering at least 1.2A is recommended to ensure reliable operation, especially when connecting peripherals. The board has onboard voltage regulators to step down the 5V input to the 3.3V required by the SoC and GPIO pins. Avoid powering the board through the GPIO 5V pin unless you are certain of your power source's stability and capacity.

All GPIO pins on the Raspberry Pi 1 Model A operate at 3.3V logic levels. This is crucial when interfacing with external components. Connecting a 5V device directly to a 3.3V input pin can damage the Raspberry Pi. Conversely, connecting a 3.3V output from the Pi to a 5V input on a device might not be recognized. For incompatible voltage levels, use a logic level shifter. For example, to blink an LED, connect a resistor (e.g., 330 Ohm) in series with the LED, then connect one end of the resistor to a 3.3V GPIO pin and the other end to the LED's anode. Connect the LED's cathode to a ground (GND) pin.

For an I2C sensor, you would typically connect its VCC to a 3.3V pin on the Pi, its GND to a GND pin, its SDA pin to GPIO 1 (which is the I2C SDA pin), and its SCL pin to GPIO 2 (which is the I2C SCL pin). The Raspberry Pi 1 Model A does not have onboard Analog-to-Digital Converters (ADC), so if you need to read analog sensors, you will require an external ADC module, which can also be interfaced via I2C or SPI.

Programming & getting started

The Raspberry Pi 1 Model A runs a full Linux operating system, typically Raspberry Pi OS. This means you can program it in various languages. For embedded projects, Python (using libraries like RPi.GPIO or gpiozero) is very popular and beginner-friendly. You can write your Python scripts on the Pi itself or develop them on a separate computer and transfer them over SSH. For more complex applications or if you prefer a compiled language, C/C++ with the WiringPi library (though deprecated, it was widely used) or direct Linux system calls are options. You can also use IDEs like Thonny on the Pi for Python development.

To get started, install Raspberry Pi OS onto a MicroSD card. Insert the card into the Pi, connect a monitor (via HDMI), keyboard, mouse, and power supply. Once booted, you can open a terminal and install necessary libraries. For example, to install the gpiozero library for Python, you would typically run `sudo apt update && sudo apt install python3-gpiozero`. You can then write a simple Python script, save it (e.g., as `blink.py`), and run it from the terminal using `python3 blink.py`. This approach allows for immediate feedback and iterative development.

Project ideas

Buying tips & gotchas