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Working full-speed (12 Mb/s) bit-banging USB Host controller
This is something I've been wanting to try for a while, but I finally had an excuse...
I've been wanting to build more devices that can communicate wirelessly. Sensors, ambient information displays, that sort of thing. To reduce the infrastructure needs, I'd like to use Bluetooth, or preferably Wifi. Problem is: I want these things to be cheap, and it's still fairly expensive to buy a Bluetooth or Wifi adapter that's microcontroller-friendly. I'd much rather stick a $5 USB bluetooth dongle on my Propeller and have a solution with simple/cheap hardware and software which is merely not impossible to write [noparse]:)[/noparse]
Anyway.. I'm still working on writing USB class drivers for it, but I have a working full-speed host controller. So far it supports Control, Bulk IN/OUT, and Interrupt IN transfers. There are a couple simple demos included: Device enumeration and descriptor parsing, a very simple HID demo, and an even simpler mass storage demo.
As you'd expect, there is a huge list of caveats for something that pushes the limits of the Propeller and the USB spec to this extent.. It uses four cogs, requires overclocking the Prop to 96 MHz, and even though the line rate is 12 Mb/s the actual usable data throughput is significantly lower.
But, this lets you talk to a lot of fun new peripherals that were previously unavailable to the Propeller. So it should be fun [noparse]:)[/noparse]
The hardware is really simple: Four resistors and a USB socket. If you try it out, let me know how it goes. Compatibility with different devices still isn't perfect. It works with most of the devices I've tried it with, but some don't work at all, and some work intermittently. But on the devices it does work with, transfers seem to be quite reliable.
My next goal is to write a simple proof-of-concept USB storage class driver ('cuz why not?) then see if I can get Bluetooth working.
Post Edited (Micah Dowty) : 4/6/2010 6:30:59 AM GMT