[Noisebridge-discuss] G1 serial interface incantation

William Heath wgheath at gmail.com
Mon Mar 16 22:13:34 UTC 2009


Hi All,
If I want to use off the shelf components, instead of making my own cable
could I use the following to create the cable you made:

http://www.tca-inc.net/usbmatousbbf.html

http://www.usbgear.com/computer_cable_details.cfm?sku=Y-105A&cats=199&catid=199

If these won't work, why not, and what would work?

-Tim

P.S.

I spoke with others in the #noisebridge irc channel and they said I could
not simply open up like /dev/usb0 with a program and write bytes out and
have it work.  It was not clear to me why this would not work.  Does anyone
know the answer?

On Mon, Mar 16, 2009 at 2:17 PM, Jacob Appelbaum <jacob at appelbaum.net>wrote:

> William Heath wrote:
> > Hi All,
> > I have started this fun project:
> >
> > https://www.noisebridge.net/wiki/Autonomous_Flying_Platform#Team_Members
> >
> > I need to find a way to control propellers etc... with the G1.  The
> easiest
> > way I know how to do this is to use the serial interface from the G1 to
> like
> > a parallax board which then connects to servos etc...  I am stuck in park
> so
> > far as I am a mere mortal and the serial inteface/software on the G1
> phone
> > is "undocumented" but does exist.  I was told that ioerror might know
> about
> > it.  I am performing the incantation to the G1 Gods/Gurus to rain down
> this
> > undocumented knowledge that I might drink deeply from that cup of
> knowledge.
> >  I also invite advice/recommendations on what hardware to use for the
> > propellers etc... in this project.
>
> I am by no means a G1 god or guru. There are better people to ask and I
> do hope they'll chime in. I am however linked to that nickname that you
> dropped and so I feel compelled to answer. ( And no, I'm not nor have I
> ever been, a woman. )
>
> The serial interface you're discussing does indeed exist on the HTC
> Dream (G1). I hear it's possible to build a cable that is a mini-usb on
> one end and a normal sized usb on the other. Between the two is a usb to
> serial device. It's just a nice way to have a set of pin outs and power;
> it's otherwise not a special cable.
>
> If you have or build such a cable, you'll then be able to access a few
> low level debuggers or boot prompts on the serial port. If you have the
> right setup, you should be able to connect the cable, attach to the usb
> serial device and set minicom to operate at 115200 8N1 (and with no
> software/hardware flow control).
>
> A photo of the mythical cable attached to my G1 is available here:
> https://www.noisebridge.net/wiki/Image:G1-two-usb-to-serial-cable.jpg
>
> This is the code for that interface (see the Android source):
> /kernel/drivers/serial/msm_serial_debugger.c
>
> From the source you'll see the following commands available when the
> phone is booted:
> pc
> regs
> reboot
> irqs
> kmsg
> version
> sysrq
>
> If you have the developer or engineering boot loader, you can do more...
>
> You can boot the phone with the camera button held down to access a
> serial boot prompt that looks like this:
> UART0:Cmd>
>
> So far I've only seen a single command 'set'. I didn't find very much
> useful information beyond that for the serial interface to the (first?)
> boot loader. Perhaps someone knows more about this? It may prove to be
> useful...
>
> Another interesting but unrelated (GSM) test function is available in
> the dialer program when the phone is booted by calling this number:
> *#*#INFO#*#*
>
> Best,
> Jake
>
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