On 16/07/2011 19:30, Jacopo Monegato wrote:
> Hello,
> i hope the tag is correct. I was wondering about this for a while. a coup=
le of years ago i bought a portable speaker, with cable and ipod dock, powe=
red both via batteries and usb. I crossed my fingers and one day i linked t=
he speaker with my pc. nothing. only power... but why? Unfortunately i don'=
t know much about USB protocol, but since it is a serial port it shouldn't =
be hard to write a software that sends the sample... or calculate the PW fo=
r a "simulated" class D then send only the 1 and the zeros... am I mad o_O?=
??? because i haven't found anything yet and my old teacher told me "good l=
uck if you want to learn usb by yourself, it's very hard to find technical =
resources of any kind"
>
> Jacopo Monegato
>   		 	   	=09

Hi Jacopo,

I don't quite understand what it is you are wanting to do with your=20
speaker exactly.
However on the USB learning front, while it is quite a complicated and=20
large subject, I'm sure many people (myself included) have managed to=20
learn to learn/use it by themselves.
It is a lot more complex than serial comms using a UART though, with=20
things like enumeration/configuration, endpoints opened before any data=20
can be actually be sent.
There are quite a few good books available (Jan Axelsons book/website=20
are excellent) and tutorials on the web, plus code and examples=20
available for various microcontrollers. The USB org website has the=20
USB2.0 spec available for download - this will give you a rough idea of=20
what is involved.
My suggestion would be to get yourself a USB development kit from=20
somewhere, based around a PIC/Atmel or similar. There are quite a few=20
cheap kits with ready to go firmware examples and explanatory=20
documentation. Check Microchip Direct, Sparkfun, and other such places -=20
I'm sure someone else will have more advice here, I don't use many of=20
these type of dev kits.
What is your level of experience with electronics, microcontroller and=20
PC programming?
--=20
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