Brennan’s take on #CircuitPython2019 #CircuitPython #Adafruit @Adafruit
Brennan provides his thoughts on CircuitPython in 2019:
I’ve been spending a decent chunk of my paid time in recent months on the CircuitPython ecosystem, doing things like testing libraries against Adafruit-Blinka, a shim that mimics CircuitPython’s core modules on Linux systems.
(For background: CircuitPython is a fork of MicroPython aimed at educational users, beginner hobbyists, etc., with full-time development staff sponsored by Adafruit.)
I guess I’ll start with some reflections on my experience in 2018 and then list some thoughts about where things are headed. None of this should be taken too seriously — my role on this one is that of a low-level software bureaucrat, and it’s an extremely safe bet I don’t know what I’m talking about.
reflection 0: python could be worse
Python and I have always been sort of an uncomfortable fit. I’ve used it here and there — Ansible stuff for configuring web servers, one-offs like a static HTML image gallery generator — but I’ve never warmed up to it much. I never got over the whitespace thing, and the claims of “executable pseudocode” that hover around the language strike me as more than a little exaggerated. Anyhow, I have shell and Perl for small-time utility scripting, and the large projects I’ve worked on have mostly been PHP. So for one reason and another, until recently, I’d probably written more lines of, say, QBasic or vimscript than I had Python.
Still and all, I’m well past the point in my working life where I’m capable of feeling anything like love for most software. Grudging toleration is about the best I manage these days. And it’s clear that Python has a set of virtues in the space it occupies.
The syntax is for the most part easy to grasp, modulo the brittleness of indentation and a few other infelicities. The built-in collection types (lists, dicts, tuples, sets) aren’t as easy for a beginner to use as something like PHP’s swiss-army-knife of an array type, but they’re also much less conceptually muddled. The language seems to encourage a straightforward procedural style with some light object orientation on top. Even if this isn’t exactly considered cool, there are far worse ways to program.
In fact, Python’s aesthetics are often relentlessly un-hip, which is probably a useful bulwark against the violently unmaintainable cleverness that infests so many language cultures in 2019.
Packaging isn’t a lot of fun to figure out, but it basically works once you get the right boilerplate in place. PyPI is a mess, but as other language-specific package managers & repositories have shown us repeatedly, it could be substantially worse.
I think most of my substantive ongoing concerns with Python are around the way bugs seem to proliferate on type boundaries, the tendency of code to spew exceptions all over the landscape in conditions the developer didn’t quite anticipate, and the swampy nightmare that is the ongoing 2-to-3 version transition. (Some of these are mitigated to an extent by the smallness of most CircuitPython codebases, and the 2-to-3 problem is sidestepped by way of aiming only for Python 3 compatibility.)
Very broadly speaking, Python’s problems are mostly in classes of problems shared by that family of dynamic, garbage-collected interpreted languages that came to prominence in the 90s and early 2000s: Perl, Python, PHP, Ruby, etc. By the same token, Python shares many of the positive qualities of its relatives. There’s a vast set of undertakings that are essentially painless in these languages and excruciating in an environment like C / C++ / Arduino.
All of this to say: I was initially skeptical, but it seems like a Python is a reasonable thing to build a hardware development ecosystem around.
reflection 0a: the workflow is pretty good
Plug in a board, get a USB drive you can drop code onto and a REPL you can access over serial.
Ten years ago this would have blown my mind, and in 2019 it still feels like kind of a revelation. In most ways, it’s a vast improvement over the ergonomics of the Arduino-style compile-upload-debug cycle. If you mess around with hardware and haven’t tried this, it’s worth playing with.
reflection 1: the hardware isn’t quite there yet
…but it’s real close. At this point, I’ve written CircuitPython code for:
- ATSAMD21E18 Cortex M0 boards (48 MHz, 32KB RAM):
- ATSAMD21G18 Cortex M0 boards (48 MHz, 32KB RAM):
- ATSAMD51J19 Cortex M4 boards (120 MHz, 192KB RAM):
- Various and sundry iterations of the Raspberry Pi
Of these, it feels like the SAMD21 boards just don’t have enough RAM to do much that would require more than one driver library. For instance, I recently offered to build my dad a remote thermometer for his pump house. The Feather M0 LoRa boards seem like they should be ideal for this, since all I need to do is read a temperature sensor on one board, transmit it, and display the temperature on the other end. I just couldn’t seem to get the headroom to import, let alone use, both Adafruit_CircuitPython_RFM9x and a driver for any of the several displays I tried. Ultimately I gave up on CircuitPython for the project, and plan to complete it in Arduino / C++ with the RadioHead library instead.
I had similar experiences when working up the Glitter Positioning System and an as-yet undocumented USB pedal-input project. In those cases, I wound up switching to the Feather M4 Express, and the contrast is dramatic. The SAMD51 feels like a Real Computer for this use case, with enough memory to easily handle a LoRa radio, GPS unit, LSM9DS1 9-DOF, and an RGB LED ring for display output all at once.
At the low end of the available hardware, you can glimpse the platform’s possibilities and do some basic projects, but there’s a good chance you’ll be frustrated trying to go anywhere beyond that. At the higher end, it’s eminently possible to do real work.
reflection 2: this could be pretty important on linux systems
This brings me to the Raspberry Pi, where (strictly speaking) CircuitPython doesn’t run, but the project as a whole has quite a bit to offer. Adafruit-Blinka is a shim that aims to provide most of the core CircuitPython modules on some common small-board computers with GPIO pins, which means that CircuitPython drivers and helper libraries can be used from regular CPython 3.x. At heart, it’s a collection of hacks, but this nevertheless feels like a game changer for a certain class of hardware projects on small Linux systems. It’s trivial to use a lot of this stuff, and that in turn opens up a ton of connections to the rest of the stuff you can do with a high-level language in a Linux environment.
At a time when it’s nearly impossible for most users to exercise any control over most of the computing hardware in their lives, this sort of thing feels like at least a small step in the right direction.
reflection 3: the community stuff is well-handled, except…
Having a code of conduct, doing most development work in the open, welcoming beginners, involving the user community in code review, etc.: In general I think this is a commendably well-managed software project, and plenty of FOSS efforts could learn something from the overall tone it takes.
On the negative side, I actively dislike Discord with its CPU-eating Slack-but-for-gamers vibe, and I continue wishing that GitHub were not eating all public-facing software development, but I recognize the accessibility these platforms afford and acknowledge that my side of these questions is presently in a state of utter defeat, so I won’t spill any more virtual ink on the subject in this context.
thoughts / hopes for 2019 and points beyond
Ok, so some notes on stuff I hope to see improve on the scale of about a year:
- Stability: Things are much better than when I first tried CircuitPython, but there are still glitches to reckon with. Occasionally a board will have to be power-cycled to get code to run correctly. Connecting to the REPL over serial sometimes hangs mysteriously or prints a bunch of garbage. Things (unsurprisingly) get downright wacky when you run out of memory. The USB mass storage stuff exhibits some unpredictable behavior—writes sometimes fail without much observable rhyme or reason. I’m sure all of this will get better; this is in many ways still a young project. Still, there’s a lot of usability to be gained just by making the whole thing a couple of notches less flaky.
- Asynchronous processing / multitasking / parallelism / event handling: I have no idea what shape it should take, but people keep wanting some kind of paradigm for handling asynchronous events in something closer to realtime, and I don’t think they’re wrong to want it. It’s remarkable what you can accomplish just by polling inputs in a tight loop, but sooner or later you want something better. Smarter people than me hash some of this out in this GitHub issue.
- CPython compatibility: This is an explicit goal of the project, so I don’t think there’s much danger of it getting lost in the shuffle. I do think it’ll improve things the closer it gets to 100%.
- Linux platforms: Right now, the Raspberry Pi is still more or less the only first-class citizen in terms of Adafruit-Blinka support. It’d be great to see a couple of other stable, widely available platforms added to that list.
- Library management: The experience of installing modules for use on the Raspberry Pi is, perhaps oddly, a lot less painful than installing them on CircuitPython boards, since you can just use
pip3. It’d be interesting if there was a nice clean way to use PyPI for dropping libraries into place on the CIRCUITPY drive or in a project directory. (Maybe this is handled by tools like Mu? I should know, but I don’t because I keep just using Vim.)- Security and privacy: The way things are going, there are eventually going to be a lot of network-exposed microcontrollers running some Python variant. Some of the people responsible for those systems will be experienced software professionals, which means that they’ll do as well on this front as software professionals usually do (i.e., completely terrible, but many of them will know that security is a consideration and when they use the tech to violate your privacy they’ll usually be doing it on purpose).
I’m not, however, convinced that the rest of CircuitPython’s target demographic is equipped to reason about these problems at all. As embedded systems continue getting smaller, more powerful, and more ubiquitous, this is going to matter more and more. The organizations and projects teaching people how to put computers in everything need to start thinking a lot harder about how dangerous it is to put computers in everything, and communicating that danger to the people they teach. I’m not sure what form that takes with CircuitPython, but I know that it should be on people’s radar as the platform expands to more devices that handle WiFi, Bluetooth, LoRa, etc. Particularly given the security track record of web projects built on similar languages.
- Community involvement: Right now, this is an Adafruit joint, through and through. That’s fine as far as it goes, but it’ll be interesting to see whether it ever truly makes the transition to something that a bunch of different orgs and individuals outside of the Adafruit bubble are involved in. I think that’d be a good thing, but there’s an inherent tension between the kind of tight control that’s built this project according to a well-defined plan and the diversified set of inputs that give projects like this a life of their own well beyond the interests of a particular company.
Anyhow. That’s probably enough rambling for one post. To reiterate, I probably don’t know what I’m talking about.
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