Low-cost low-pin count MCU with USB Host support

Check NXP and ST.

What does low pin-count mean to you? Less than 1000? Less than 100? Less than 10?

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Tim Wescott 
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http://www.wescottdesign.com 

I'm looking for work -- see my website!

SAM D21 by Atmel is a Cortex-M0+ MCU. NXP and ST integrate USB Host/OTG support starting from Cortex-M3 only.

Smaller is better :-) Beside supply pins, USB pins, debug/programming pins I need maximum additional 5 pins.

nope.

Frescal...ehm.. NXP Kinetis have USB also from M0+, Check the KL series

Bye Jack

There's also the PIC32MX2xx range but it's a MIPS core, not an ARM core.

Simon.

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Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP 
Microsoft: Bringing you 1980s technology to a 21st century world

Il 07/06/2016 14:49, Jack ha scritto:

You are right, I missed Kinetis MCUs on NXP website. They seem cheaper than Atmel SAM D21 MCUs.

Thank you for your suggestion.

Yes, that can be confusing if you are not used to the fact the USB standards group redefined the meaning of the word "full" in the presence of 480Mbps USB. When the latter came along they called it high speed USB and kept the full speed description for 12Mbps USB.

I remember comments at the time saying people would find it confusing.

Simon.

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Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP 
Microsoft: Bringing you 1980s technology to a 21st century world

Yeah, I found it confusing. But it is a name and names are not always descriptive. It would have been more confusing if they called 480 Mbps "full" speed. I suppose they could have given it some other name like "not quite full speed" or "a bit less than full speed". ;-)

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Rick C

I don't know why it is confusing. "Full speed" always refers to 12Mbps. "High speed" always refers to 480Mbps. It's quite clear, noone says full speed to 480Mbps, or high speed to 12Mbps . Maybe "USB2.0" is confusing, because sometimes a manufacturer doesn't support high speed, only full speed, but it may still say "USB2.0". However, they specify the max. speed, for example "USB2.0 full speed" :)

It was more confusing when high speed USB was new to people because people unfamiliar with the history of USB might think "full speed" meant they were getting a top of the line product when it came to speed.

IOW, in those days, then they saw a product described as "full speed", did they think they were getting a 480Mbps product or a 12Mbps product ?

Simon.

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Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP 
Microsoft: Bringing you 1980s technology to a 21st century world

Yup. Great scam. Truley a triumph of marketing over the forces of truth and honesty. There are, what, 4 different speeds of USB? And "full speed" is second slowest?

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Grant Edwards               grant.b.edwards        Yow! I have seen these EGG 
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Do you think so? I may say it's technology advancing. With backward compatibilities. I am, for example, very happy that my USBASP dongle (a "low speed" 1.5Mbps) still works, even on USB3.0 ports...

I was referring to when 2.0 came out. Calling the mid speed "full speed" is of course confusing if you take the term at all at its face value.

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Rick C

Arguably they should have picked better names for low-speed (1.5mbps) and full-speed (12mbps) for USB 1.0, but given that the names existed, and were in very widespread use when USB 2.0 became a thing, what could you do? Depreciate the name on most of the gear out there? Redefine it? Those don't really sound like more palatable choices.

They thought they were getting the fastest speed available.

Well, I would have chosen "1.5 meg" and "12 meg". But that's just me be silly.

I know: I shouldn't attribute to malice that which can be explained by stupidity and incomptetence. It's just a happy coincidence that the stupid mistake turned out so that it fooled 99% of the population into thinking old, slow junk was top-of-the line gear.

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Grant

Probably my first choice too, but probably hard to get past marketing. OTOH, that's not without its own problems. First "1.5", "12", "480", "5" and "10" makes for a pretty ugly set of names, and second, it's hardly as future proof as you'd like. Consider Ethernet, which basically does follow that naming scheme (ignoring the plethora of PHYs at each speed), plenty of 10Gb Ethernet cannot connect at 100Mb, so if you happen to plug a fast Ethernet device into a 10GBb port, you going to get a 10Mb connection (at best). Try to condense that into a simple label...

Devices that draw relatively large amounts of power from USB make even more of a mess.

And trying to simplify things too much, or at least to the point where many of your users will understand it is a common problem.

I was helping someone buy an air compressor a couple of weeks ago. Air-powered tools have two parameters for the compressed air source - a required pressure, and a required volume of (compressed) air (usually PSI and SCFM in the US). Likewise most compressors also have those two ratings, usually at several different points (5.0scfm at

40psi, 3.0scfm at 90psi). Pressures is usually not an issue, but the SCFM rating is a long-standing bafflement to many people, especially seeing as it varies with the output pressure on most compressors. So I've started seeing people selling air tools with a "rating" related to the size of the compressor's tank - IOW, "needs 10 gallon compressor". (And yes, I know that a large tank may permit intermittent operation, even if the compressor does not produce enough air for continuous operations). Worse they've simultaneously started hiding the "real" ratings... Grrrr...

I can sympathize with the manufacturers - they're not wanting people to buy tools that won't work, but there doesn't appear to be a simple (enough) way to communicate the requirements, that remains reasonably accurate.

I don't think the problem was nearly that bad, 95% can barely find the letters "USB" on the packaging.

Was another name even needed? They're already called USB 1, 2, 3, so why not just refer to the speed by the standard version that introduced it?

Yep, that is dopey. Should be power (watts) at pressure, for continuous use, since that reflects the actual requirement.

Clifford Heath

That is a problem we still have. Saying a device supports USB 2.0 does not mean 480 Mbps. It may be 12 Mbps or even 1.5 Mbps. Each revision of the standard provides for multiple speeds which each have names.

Except if you are building and using these things you can measure PSI and perhaps airflow, it's harder to measure the output in watts.

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Rick C

USB1 was 1.5 and 12, USB2 was 480, USB3 5G and USB3.1 10G (with spec devices not needing to support the highest speeds in general). So what are you going to call the two speeds in USB1?

Errr...?

SCFM at a given pressure *is* effectively power.

Or consider the analogy to be voltage (PSI) and amperage (SCFM) if you prefer.

On an air compressor, the output pressure is adjustable, and tools work at various pressures - and have requirements for some amount of air at that pressure. There is also no simple ratio of pressure and volume that compressors supply. In particular, less expensive compressors tend to have a much lower duty cycle at high pressures (because of the great amount of heat generated, and limited cooling), this is true of larger compressors as well, but to a more limited extent (and usually only near the maximum output pressure).

So specifying both is no sillier than specifying that some device needs 2A at 5V and another 1A at 10V - that they both need 10W is interesting, but you can't actually use them with just that knowledge.