[Coco] BIGGEST PROBLEM

Allen Huffman alsplace at pobox.com
Tue Mar 7 11:58:48 EST 2017


> On Mar 7, 2017, at 10:49 AM, Brett Gordon <beretta42 at gmail.com> wrote:
> 
> Only heaviest of the 32 bit PIC controllers can do USB.  After perusing the
> PIC's datasheets,  I'm guessing the PIC's USB controller is limited too.

The USB stack Microware used was fully in software, on 32-bit architecture, and had many limitations. Beyond Windows, Mac and Linux, everything else seems real hit and miss.

The embedded things I work with that have USB ports have done so with dedicated hardware. Even the ethernet and WiFi is usually done with chips that handle the full TCP/IP stack and protocols. It's just a cheaper solution for a dedicated purpose.

And that's the key. "One USB port to rule them all" lives on desktops and high end machines. But most everything else uses USB chipsets that do whatever they need - read/write to USB drives, talk to USB serial devices, mice, keyboards, joysticks, etc. Why use all the CPU cycles and RAM if you can get your end goal by spending a few bucks on a chip that handles it all, leaving the CPU free to do actual work.

I have several gadgets on my desk at work that have USB ports. Much like the USB ports on devices like Apple TV and such, these are not generic ports. They only handle some items -- flash drives, serial consoles, etc. No hubs, either. But how many flash drives do you need to do a firmware update?

Nothing wrong with that :)

		-- A




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