XCore Exchange

It would be great if someone ported this to XMOS, when we do not need high speed !?

http://www.obdev.at/products/vusb/index.html

V-USB is a software-only implementation of a low-speed USB device for Atmel’s AVR® microcontrollers, making it possible to build USB hardware with almost any AVR® microcontroller, not requiring any additional chip.

To be able to use USB with only a 12 MHz clock.

It's not all that useful on an AVR as it can't do anything else when the USB is running. Someone has even implemented full-speed host mode in software on a Parallax Propeller:
http://forums.parallax.com/forums/defau ... 5&m=440787
Something like that for XMOS chips would be nice, as well.

I had a look at a similar AVR project (*) a few days before. They used an Attiny 2313 for less than 2 Euro to implement an USB <=> SPI master. IIRC to clone a standard ISP. That's cheaper than an FT2232 and even available in DIP package for the breadboard fans and home brewer.

This solution has some limitations, of course. <half knowledge>e.g. it doesn't support bulk transfer and therefore cannot replace a real USB <=> UART bridge.</half knowledge>

@lillitroll: Funny that we had the same idea at the same time. I thought about it, but I think it's only possible if one reads the USB standard regarding the correct timing. The author of the Attiny stuff wrote that his implementation is still according to the standard, but pushes it to the limit.

However, it can't be too complex, since the AVR implemetation fits into 2 kByte of flash

(*) http://www.xs4all.nl/~dicks/avr/usbtiny/

Thomas

(Interesting voltage regulator in the schematic above, D1 + D2 :lol: )

skoe wrote:@lillitroll: Funny that we had the same idea at the same time.

Well, it was not my idea, I stole it from some chat on the #XCore IRC. I wanted to test it on a larger public to see if it was for any use on a XMOS chip.

Interesting project - With a USB Transceiver (basically a USB line buffer) you should be able to do full speed (12 Mbps). If I remember correctly you FS is like 10x faster than LS?

Saves a lot of hassle if you don't need HS for low bandwidth apps...

Hi,

Silabs make a range of souped-up 8051-based USB chips that are very easy to use. I put a C8051F34 into a USB interface that to control a set of 4-20mA converters.

John.

Yes, it would be nice to have USB connection between PC and XMOS. I am thinking about some kind of external accelerators, random number generators, etc