LED Strip HAT Mini
Les Pounder, unlike Gremlins, loves bright lights. So when a new board offered easy access to controllable RGB LEDS, he built a new gizmo!
Les Pounder, unlike Gremlins, loves bright lights. So when a new board offered easy access to controllable RGB LEDS, he built a brand new gizmo!
Making lights flash with a Raspberry Pi is a rite of passage for any budding maker. There are many ways to do this, the most simple being the humble LED. But for some makers the lure of controlling a long string of programmable, addressable RGB LEDS is too much. The LED Strip HAT Mini from Pimoroni is made to fit on top of all 40-pin models of Raspberry Pi, but is also designed to match the footprint of the Pi Zero range. The board fits above the GPIO pins, and can be secured in place using M2.5 standoffs.
The board can work with three- and four-pin addressable LED strips; this would be Apa102/dotstar and Ws2812/neopixels. The switch on the board enables us to switch from three to four pins with ease. External power is necessary for long strings of LEDS, and in our tests we ran 144 Apa102/dotstar LEDS with an external 5V 2.5A supply. The onboard INA220 power monitor chip provides data on the power consumption – up to 10 Amps – and the health of the power supply. This is useful for larger installations. Our LEDS pulled around 70ma during our simple colour change test. There are two connections on the board that enable two strips of LEDS to be connected at once, and to be independently controlled using a Python package.
The Python package is called Plasma, and is a generalpurpose package for a range of Pimoroni products, most notable the Plasma arcade buttons with built-in APA102 LEDS. Installation is via an install script on the Pimoroni Github page and it works well, but because this is a remote script it’s best to check the contents before running. Plasma can be used to create static LEDS or animated sequences. Once we’ve told the board where to find the LEDS and how many there are, we just need to use standard Python structures to set the value for each LED. For example, our test used a ‘for loop’ to iterate over each LED, setting the colour and timing to create a wave of colour along the strip. There are plenty of examples in the code download via the Pimoroni Github page.
Board applications
So why should we use this board instead of just plugging in directly to the GPIO? First, it simplifies the connections. When using any addressable LEDS we need to ensure that we deliver an adequate power supply and the board offers an easy-to-use connector for just this issue. If we tried this ourselves, we would need a breadboard/simple circuit to ensure that the LEDS are supplied the correct power.
Second, the Python library is easy to use and abstracts many of the issues found with these LEDS. For example the frequency at which data is communicated from the Pi to the LEDS is vital for Neopixels. Finally, the board can work with two different protocols (WS2812 and APA102) with ease and this will help makers to get started quickly.
This is a great board that shows the usual level of Pimoroni quality and forward thinking. It provides a robust platform for RGB LED light projects and it reduces the complexity that a user would experience when attempting their first project. If you’re an expert with RGB LEDS then LED Strip HAT Mini still offers a great way to add your favourite LEDS to a project. For £15 this is a bargain price for what will become a go-to board for many makers.