this post was submitted on 07 Nov 2023
13 points (84.2% liked)

Single Board Computers

1219 readers
1 users here now

A community for the discussion of all single board computers. Raspberry Pi is ok, but there are so many other boards now that get looked over that deserve attention.

Post news, questions, your setups, guides, anything that has to do with SBCs. Server wide rules apply

founded 1 year ago
MODERATORS
minnix@lemux.minnix.dev
13
The Differences Between Single-Board Computers vs. Microcontrollers (www.okdo.com)
submitted 11 months ago by minnix@lemux.minnix.dev to c/sbcs@lemux.minnix.dev
15 comments fedilink hide all child comments
top 15 comments
sorted by: hot top controversial new old
[–] Valmond@lemmy.mindoki.com 9 points 11 months ago* (last edited 11 months ago) (1 children)

That's some crappy cookie / tracking crap right there.

I thus did not read the article, but for me single board computers usually sports an OS, microcontrollers don't.

More?

The first have at least 0.5GB RAM (up to many), several cores, and somekind of hard drive simila : onboard + SD card and runs sole Linux flavour.

The second is usually a single core processor with all it needs in it. Like up to 256KB ram and that's about it. Program it over some serial or usb link and it just runs when you apply power to the board.

Edit: up to 256KB! I have some with 32KB for example

It's because usually there are no graphics on these small beasts so it's basically all for (your) running code.

I saw in the answers (funny you get so many because of a typing mistake:-) there are effectively weird ones with loots of memory, IDK what their usecase is for.

[–] dragontamer@lemmy.world 7 points 11 months ago* (last edited 11 months ago) (2 children)

The second is usually a single core processor with all it needs in it. Like up to 256MB ram and that’s about it. Program it over some serial or usb link and it just runs when you apply power to the board.

You mean 256kB, right? Lol.

The vast majority of uCs are under 256kB of RAM, with just a few exceptional ones reaching into 1MB of RAM or 2MB.

256MB of uC is pretty much unheard of IMO. That's 2Gbit, which is well into DDR territory. And if you're hooking up DDR, DDR2 or other "grown up" memory interfaces to a chip, its definitely a microprocessor by then.

That's the thing, 128MB or 256MB of DDR2 is like $4 or $6. To get over 2MB or 4MB on a uC, you'll have to spend for $10, or $15 uCs (or alternatively, "grow up" to like SDRAM). But SDRAM is still like 8MB for $4, so you're very far away from DDR2 or DDR3 "grown up computer parts".

Microprocessors target working with "grown up computer parts", which implies a degree of power-consumption that puts even the smallest microprocessor far beyond the power-envelope of the biggest microcontrollers.

[–] Valmond@lemmy.mindoki.com 2 points 11 months ago

Ha ha yeah lol, thanks for the correction.

[–] agent_flounder@lemmy.world 2 points 11 months ago (2 children)

Yeah most are sub 1MB but e.g. STM32h7 (ARM Cortex M7) has 1MB ram. So maybe that's a good upper limit. I am a bit behind the times so maybe there's something miceocontroller-ish with more ram out there idk.

[–] dragontamer@lemmy.world 3 points 11 months ago* (last edited 11 months ago) (1 children)

The "Biggest" uC I'm aware of are NXP's i.MX RT devices. Basically: NXP is making i.MX Crossover Microprocessors (aka: the smallest microprocessor), and i.MX RT crossover microcontrollers (aka: the largest microcontrollers). So yeah, that "RT" means they're still microcontrollers, but way bigger than normal.

https://www.nxp.com/products/processors-and-microcontrollers/arm-microcontrollers/i-mx-rt-crossover-mcus:IMX-RT-SERIES

Today, it looks like the biggest i.MX RT is a 5MB SRAM microcontroller. Which is... bigger than I expected.

[–] agent_flounder@lemmy.world 1 points 11 months ago (1 children)

Oh wow. I hadn't heard of those. Thanks. Really curious now.

[–] dragontamer@lemmy.world 4 points 11 months ago* (last edited 11 months ago)

I dunno, I think the i.MX RT500 are completely absurd.

  1. 0.40mm pitch BGA, okay so we're looking at an expensive PCB anyway. Like, what the hell? You need like 3mil trace / 2.5mil space to even breakout.

  2. You can get an MPU with full scale Linux in the $5 / chip + $2 Power-management IC + $4 DDR2 128MB + $4 NAND 1GB Flash at roughly the same price, with easier to solder 0.80mm pitch BGAs.

  3. The i.MX RT500 is expensive at $30 Qty1 and $20 in larger-scale bulk quantities.

So I'm not entirely sure what the hell the point of i.MX RT500 is. The NXP Microprocessors are literally cheaper... even after buying RAM and Flash. I mean, someone wanted it, so I recognize that its been created for someone. But... its difficult for me to imagine how or why.

[–] ttmrichter@lemmy.world 1 points 11 months ago (1 children)

I've never seen anything I'd call an MCU that has more than 2MB of SRAM (though a lot of them have the ability to address external buses for Flash and SRAM both semi-transparently, so there may be some dev boards that give more).

[–] dragontamer@lemmy.world 2 points 11 months ago* (last edited 11 months ago) (1 children)

In case you missed the sibling comment: I just found the iMX RT500, a 249-pin BGA 'Microcontroller" with 5MB of SRAM.

https://www.nxp.com/products/processors-and-microcontrollers/arm-microcontrollers/i-mx-rt-crossover-mcus/i-mx-rt500-crossover-mcu-with-arm-cortex-m33-dsp-and-gpu-cores:i.MX-RT500

Which is absolutely the largest "microcontroller" I've ever heard of. But you're right in that 2MB is already an absurdly huge size in most cases.

[–] ttmrichter@lemmy.world 1 points 11 months ago (1 children)

Wow. At that point my reaction is ... it would be better to have an SoC. I mean I'm working with kit that typically has 64KB to 128KB of SRAM and thinking that I'm blessed with resources! 🤣

[–] dragontamer@lemmy.world 1 points 11 months ago* (last edited 11 months ago) (1 children)

Yeah, there's entire MPU platforms that are cheaper than the iMX RT500.

And the 0.40mm and/or 0.35mm pitch BGAs just confuse me even further. (Seriously, who is getting like 2.5mil trace/space and like 6 layers PCB for a microcontroller? But cannot afford the MPUs?)

I'm guessing iMX RT500 has some power-benefits. But... it just seems absurd all together to me. But good luck on NXP on finding customers for that thing.

[–] ttmrichter@lemmy.world 1 points 11 months ago

I think its sole use case would be for that very, very, very narrow point of intersection between "extreme power management needs" and "extreme processing requirements".

And it seems a bit quirky to make ... that ... chip for it.

But hey! At least it isn't the STM32MP1! 🤣

[–] ttmrichter@lemmy.world 6 points 11 months ago (1 children)

Yowza! Talk about a completely vapid and worthless article! Did an AI write that?

[–] minnix@lemux.minnix.dev 6 points 11 months ago (1 children)

I'm just glad I posted something that got users actually talking to each other for the first time lol.

[–] JackSkellington@lemmy.world 3 points 11 months ago

That’s what I thought ahaha Lots of interaction on this one