Bitbang USB protocol?

[achilles03]

So maybe bitbang isn't the right word, but I am wondering if anyone has attempted USB communication on a chip without integrated USB functionality. I'm aware chips like the 18F2550 include that functionality, but are roughly 3$ more each and that adds up if you want a small production run. I'm using the 18F25K20, which can achieve 115.2k as defined by the SPBRG register. Voltage levels aside (for now), has anyone attempted coding the USB protocol to achieve some level of USB communication? I'm assuming a PC would have to recognize it as a VCP?

Thanks in advance!
Dave

[richard]

has anyone attempted coding the USB protocol to achieve some level of USB communication?

only in their dreams


https://en.wikipedia.org/wiki/USB_communications

[Jerson]

Yes, it has been done on an AVR. See this link for the V-USB

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