Comment by nkozyra
4 hours ago
They're all just single board computers, generally low-powered (literally and in the sense of capability, particularly memory)
They're generally intended to run flashed firmware and be single-purpose. They usually come bundled with peripheral components and typically have breakouts to add more (pots, sensors, etc).
They're great for doing one thing (though some support firmware switching), and you can build the 'software' for them pretty easily using Python or C-like variants.
So for hobbyists they're perfect. You want a quick LED christmas display you can toggle between Rudolph and Santa from a quick network call? You want a humidity sensor in your bedroom? You want to create a networked security camera? These are the types of use cases for MCUs.
BTW, I was just researching this last week (the christmas display) and ESP32 has a matter compatible chip now... so you an control all this from Apple Home and the other Smart Home platforms.
Absolutely mind blowing. What a fun time to do side projects.
I think you're confusing Matter and Thread. ESP32-H* have Thread radio, but every esp32 that has wifi is able to talk Matter over WiFi.
I have virtual power outlets and fans that actually just some process on linux.
esp32 has wifi so it it's trivial to hook it to mqtt which then exposes it to home assistant
They're not single board computers. They're microcontrollers. Or rather they were until this new chip was introduced.
>they're not single board computers.
what's the meaningful distinction now? It isn't all SoC anymore and it has had a linux capable MMU since S3, even if it required a lot of work.
The only real difference at this point is pure numbers, and i'm not that keen on defining microcontrollers as "those things with less ram than an SBC.", and if it's a microcontroller because it requires bare-metal flashes; well then I point to the older S3 MMU boards running busybox.
A single board computer contains an application processor, not a microcontroller. They have very different design goals.
A microcontroller is a type of processor that offers very fast startup, predictable timing and direct access to hardware peripherals. In contrast to application processors that are intended to run an operating system, a microcontroller will not have OoO execution, multiple tiers memory (eg cache and dram). Usually they also lack an mmu and multiple privilege levels of execution (although that seems more common on riscv microcontrollers). All this means microcontrollers aren’t designed to run Linux (even if someone does figure out how to do that) or clock in the gigahertz, but instead provide very predictable low latency execution required for managing real time systems. For example they might need to operate a set of mosfets with microsecond accuracy to efficiently and safely control a motor.
Perhaps the most straightforward difference is right in the name — a single-board computer is a whole board. A microcontroller refers to just the IC itself. The thing that's on the article's picture is a dev board for an MCU, not the MCU alone. That's just the chip at the top with the Espressif branding.
Now, if you want to argue that the difference between a dev board and an SBC is kind of vague, I agree on that front. I'd argue that the distinction is mostly the vendor's intent. E.g. if I sell the ICs in bulk and _also_ sell a board with that IC, it's probably a dev board. If I source the ICs from somebody else, only sell the assembled boards, and ship a general-purpose OS with it, it's probably an SBC. With sufficiently powerful hardware (like this thing seems to be), you could use a dev board as an SBC, and that is basically what this article is all about.
> what's the meaningful distinction now?
SBC is a PCB which includes ports for power, I/O, often other parts like sensors on it. Esp32 is a MCU. You can put an Esp32 on a PCB and call it an SBC. (Although semantically SBC usually refers to something that runs a GPOS, but perhaps that's flexible or changing)
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The tangible hardware difference is the MMU. S3 didn't have a proper one. This new chip does. But the biggest difference is the intent. Microcontrollers focus on peripherals and are used for interfacing, data conversion and signal processing. They're meant to run either bare metal firmware or small RTOS. OTOH microprocessors have in addition to an MMU big caches, high IPC numbers, wide bus lanes, everything you need to run different workloads as fast as possible.
Technically a chip can excel at both.
you can also use Rust.
Yea - I think this is one of Rust's core use cases.