The versatility of the Raspberry Pi can be significantly expanded with hardware extensions that are plugged directly onto the board. These extensions, known as “Hardware Attached on Top” (HAT), simply plug onto the board’s GPIO pins and come with plastic spacers to prevent short circuits. These HATs have grown in popularity in recent years, with the official HATs and manufacturer Pimoroni being particularly notable.
One such HAT is the DAC, which allows you to connect the Raspberry Pi to speakers or a stereo system, effectively turning it into a streaming box. The Raspberry Foundation offers various models of Digital Audio Controllers (DAC) that cater to different speaker setups. Additionally, there is the Raspberry Pi Build HAT for Lego hobbyists, the Raspbee II for home automation, and the Game HAT for turning the Raspberry Pi into a mini-game console.
For machine learning projects, the Braincraft HAT provides a solid basis, although it requires a good understanding of the subject matter. And for a simple touch input, the resistive 3.5-inch display from Waveshare is a great option, with a larger 5-inch capacitive touch display also available for more tablet-like functionality.
Ultimately, it’s important to consider compatibility before purchasing any of these HATs, as the focus is on the Raspberry Pi 4, but they may also fit older or newer models. While the prices for these HATs vary, they offer a wide range of possibilities for hobbyists and professionals alike looking to expand the capabilities of the Raspberry Pi.