HackSpace Magazine Issue 56: CircuitPython and NeoPixels #CircuitPython #RaspberryPiPico @HackSpaceMag
HackSpace Magazine — Issue 56 features an article on CircuitPython sequences and adding brightness to NeoPixels – learn to use Python’s dunder methods to add new features to your classes.
In CircuitPython, PIO State Machines have a new feature: background_write. This is a way of creating a set of data that will then be sent to a PIO program in the background (either once or in a loop). This means that, if you’ve got a lot of data to send (or need to send it continuously), you don’t have to wait around for it to finish sending. As soon as you issue this instruction, the system will start the transfer, and then return control of the processor back to the program so your code will continue to run while the data CircuitPython sequences and adding brightness to NeoPixels transfers.
It’s not as fully featured as the DMA control that you can get if you program in C, but it is easy to use and works well in many use-cases. Let’s take a look at one great application for this. Regular readers will know that we’re big fans of WS2812B LEDs – sometimes known as NeoPixels. However, one problem is that although they have 24-bit colour, there is no gamma correction. This means that the 8 bits per colour channel is spread evenly through the colour range, and there are very few brightness levels available at the low end.
There is a way around this – dithering. Basically, this means flicking between different brightness levels very quickly. Let’s take a look at how to do this. Along the way we’ll look at Python sequences – this is the mechanism that lets us create list-like objects.
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Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.
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