[linux-dvb] Re: Request: docs/specs for dibusb

[Patrick Boettcher <patrick.boettcher@desy.de>]

On Mon, 13 Sep 2004, Henning Günther wrote:

> Hi,
>
> as I'm very interested in
> 1) getting my Twinhan VisionPlus DVB-T device running under linux

Hi,

Today morning I did another commit for the dib3000mb. With it I was able
to receive mpeg data. Therefore one of the channel-tuning-values (when
using tzap, for example) has to be auto (e.g. INVERSION_AUTO instead of
INVERSION_ON), so that the autosearch process is initiated. I will work
this problem later.

> 2) learning how to write device drivers

I was starting with it this year. I would recommend to start writing a
driver for an USB device, unless you have the specs for a pci device. USB
devices are quite easy to reverse-engineer and easy to write in linux. For
making the first steps in kernel programming it seems to be a good way.

> I'd like to ask if it would be possible to release the
> specifications/documentation on which the dibusb driver is based on. I'm
> not sure if I will understand it but it might would be a great learning
> start-point for me. Until now I only developed some user-space software
> in C.

DiBcom did not released specs for the dib3000mb, and won't do it, unless
you sign a NDA. They only have a comprehensive specification, wherein
beside of the registers, also the algorithms are documented. The only
freely available docs are the dib3000mb-sources.

The only thing they gave me, was a GPL'd linux driver. This driver was not
implemented using the Linux DVB-API, but an own one. And they are open for
any questions. Furthermore they provide a firmware that should work with
all of the dibusb-devices. The firmware is HEX-format (binary).

I extracted the i2c registers and gave them names (dib3000mb.h). In the
original DiBcom driver the register have been passed directly, quite
difficult to read. Additionally I compared the values to the ones I got
from reverse engineering.

The dib3000mb.[ch] files contain all information about important registers
and their values. I collected them from the driver source DiBcom sent me.

I hope I could make things about dibusb a little bit clearer.

Patrick