Get more fun from your Raspberry Pi Zero W
By putting a HAT on your Raspberry Pi Zero you can take your adventures further. Les Pounder examines five of the best.
When the Raspberry Pi was released in 2012, there were no add-on boards for many months, the first being the Gertboard, developed by in-house engineer Gert van Loo. This was a massive board designed to break out the GPIO and provide analogue to digital inputs, buffered pins, a motor controller and an AT Mega compatible microcontroller.
Being the first board, Gertboard made quite an impression and we soon started to see more for the Raspberry Pi. Companies such as Pimoroni, Cyntech, 4Tronix and more started to release their own boards, all designed for the then standard 26-pin GPIO, and the market exploded with devices to help everyone with everything. Early boards offered traffic lights, simple motor controllers and protected GPIO pins, and all were designed to enable different types of projects to be realised quickly and easily. But what each board also presented were a series of design challenges, most notably the dimensions of the devices, which at times could range from stripboard circuits to multilayer breakout boards, such as the Gertboard. What was needed was a standard.
Fast forward to the arrival of the B+ in 2014 and here we see a new standard for add-on boards: HAT, Hardware Attached on Top, which established a set of dimensions with which a board can be designed to fit atop the Raspberry Pi, and held in place by the new 40-pin GPIO and the screw holes present on the Pi. The board was also expected to use an EEPROM to communicate with the Raspberry Pi via new pins present on the 40-pin GPIO. The HAT standard was not a formal standard, but if you wished to call your board a HAT, then you needed to follow those guidelines.
In reality, anyone can make an add-on board... and indeed almost everyone has. There’s also the pHAT standard, designed by Pimoroni for any board intended to work with the Pi Zero. This standard led to many new smaller boards being developed, and not just by Pimoroni. The standard is open for everyone to use and we now see many community members using it in their latest boards.
In 2017 there are now many different add-on boards, from simple community-made short run kits all the way to mass produced pre-assembled products for home automation, high-quality audio or space exploration.
The beauty of the add-on board is that it can excite and inspire the user. Sure, making an LED blink is fun, but building a robot and learning how to control motors based on sensor input is a whole lot more fun.
In this feature we take a look at five boards that provide extra functionality for your Raspberry Pi Zero, or other 40-pin GPIO Raspberry Pi. We look at how to add sound to any sized project. How to incorporate analogue inputs for sensors and components. Then we look at boards that can help anyone to build a micro-sized robot, a digital light show or travel back in time... well, kind of.