Adafruit_BusIO-ification for prettier, easier-to-maintain Arduino libraries

Ever since we’ve started writing/porting CircuitPython drivers for sensors and displays and such, we’ve fallen in love with `busio` – our generalized I2C and SPI API which takes out the repetitive parts of writing drivers: i2c address scanning, writing registers, reading chunks of data and concatenating it, dealing with repeated-start chips. After doing a bunch of drivers, we started looking at our Arduino libraries with an itchy nose. Sure they worked, but they’d been building up a decade of cruft and low-level interfacing.

So we’re doing a bit of a scrubbing for our older libraries, to ‘busio-ify’ them. Carter has been taking the lead and it is soooooooooo satisfying to look at the pull requests. For example, this one was approved today:

(yes we use a stack single-element array for readability. yes we are well aware we could pass in the local’s address. yes its on purpose)


Because Adafruit_BusIO now does the annoying “we can only read/write 32 bytes at a time but sometimes we have a larger buffer” management, we have lovely diffs like this one from


We’re so happy to see this happen. Adafruit_BusIO handles I2C, hardware and software SPI with fast-io bitbanging. It also can do things like manage ‘registers’ and variable-size/offset bit-fields and will do all the error-prone math for you. There’s more memory used both flash and RAM, but that’s what good reusable-software engineering practice is all about!

Check out the Doxygen docs here and our examples here

Then, tune in to the Adafruit GitHub repo to see the libraries as they’re updated each week to BusIO.

As 2022 starts, let’s take some time to share our goals for CircuitPython in 2022. Just like past years (full summary 2019, 2020, and 2021), we’d like everyone in the CircuitPython community to contribute by posting their thoughts to some public place on the Internet. Here are a few ways to post: a video on YouTub, a post on the CircuitPython forum, a blog post on your site, a series of Tweets, a Gist on GitHub. We want to hear from you. When you post, please add #CircuitPython2022 and email to let us know about your post so we can blog it up here.

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