[Coco] BIGGEST PROBLEM

[Mark J. Blair]

> On Mar 7, 2017, at 08:49, Brett Gordon <beretta42 at gmail.com> wrote:
> 
> The Raspi has a very simplistic USB interface.  Most of the heavy lifting
> is done by the ARM cpu.  It eats about %20 of its CPU resources.  I doubt
> our hundreds-of-times-slower 6809 could do software USB with %100 of it's
> cycles.

The lowest USB bit rate is nearly twice the clock speed of our 6809-based CoCos. There are many, many, inexpensive microcontrollers with built-in USB interface hardware, however, including both device-only and USB OTG ("On-The-Go"; supports operating as either a host or a device). The difficult part about implementing a USB host is writing drivers for any peripherals which one might want to plug in. The hardware part is not difficult or expensive.

> But I'm sure one of our *many* software people wouldn't mind spending
> $1000's on the USB spec ;)

The USB specs are available for free:

http://www.usb.org/developers/docs/


-- 
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/