where to connect for extension ?

classic Classic list List threaded Threaded
6 messages Options
Reply | Threaded
Open this post in threaded view
|

where to connect for extension ?

Alessandro Sappia
Hi
Me and some friends wants to connect the freerunner to some kind of sensor.
We saw that the debug connector give us the SPI bus.
is it a good choice ?
is there a point where to take power near there (the debug connector doesn't
export it...

thanks for help. (we're good in coding, but awful in electronics :P)


--
Alessandro Sappia
[hidden email]

_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware
Reply | Threaded
Open this post in threaded view
|

Re: where to connect for extension ?

Al Johnson
On Friday 21 November 2008, Alessandro Sappia wrote:
> Hi
> Me and some friends wants to connect the freerunner to some kind of sensor.
> We saw that the debug connector give us the SPI bus.
> is it a good choice ?

It has been suggested in the past. I don't know if anyone's actually tried it
yet though.

> is there a point where to take power near there (the debug connector
> doesn't export it...

R4701 and R4702 next to the debug connector have one end on the IO 3.3V line,
but may not be a good place to pull power from. R7802 on the other side of
the speaker has the 3.3V supply for the accelerometer which may be better. It
probably depends on your power supply requirements though.

I assume you've found the schematics:
http://downloads.openmoko.org/schematics/GTA02/

> thanks for help. (we're good in coding, but awful in electronics :P)



_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware
Reply | Threaded
Open this post in threaded view
|

Re: where to connect for extension ?

Alessandro Sappia
On Sat, Nov 22, 2008 at 11:46 AM, Al Johnson
<[hidden email]> wrote:
> On Friday 21 November 2008, Alessandro Sappia wrote:
>> Hi
>> Me and some friends wants to connect the freerunner to some kind of sensor.
>> We saw that the debug connector give us the SPI bus.
>> is it a good choice ?
>
> It has been suggested in the past. I don't know if anyone's actually tried it
> yet though.

which ones are the connection used in some other projects ? I wasn't
able to fount any
project involving some hardware extension.

>> is there a point where to take power near there (the debug connector
>> doesn't export it...
>
> R4701 and R4702 next to the debug connector have one end on the IO 3.3V line,
> but may not be a good place to pull power from. R7802 on the other side of
> the speaker has the 3.3V supply for the accelerometer which may be better. It
> probably depends on your power supply requirements though.
>
> I assume you've found the schematics:
> http://downloads.openmoko.org/schematics/GTA02/
>

Yes, we have the schematics, but we really miss a good hardware hacker
between us :)
the 3.3V supply seems fine. le'ts give it a try. we have to give power
to an OPAMP.

I didn't check if the soundcard is easily reachable, but we may
substitute the ADC on the
external sensor with it (opamps are always needed to get a bigger signal).

> _______________________________________________
> hardware mailing list
> [hidden email]
> http://lists.openmoko.org/mailman/listinfo/hardware
>



--
Alessandro Sappia
[hidden email]

_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware
Reply | Threaded
Open this post in threaded view
|

Re: where to connect for extension ?

Al Johnson
On Sunday 23 November 2008, Alessandro Sappia wrote:

> On Sat, Nov 22, 2008 at 11:46 AM, Al Johnson
>
> <[hidden email]> wrote:
> > On Friday 21 November 2008, Alessandro Sappia wrote:
> >> Hi
> >> Me and some friends wants to connect the freerunner to some kind of
> >> sensor. We saw that the debug connector give us the SPI bus.
> >> is it a good choice ?
> >
> > It has been suggested in the past. I don't know if anyone's actually
> > tried it yet though.
>
> which ones are the connection used in some other projects ? I wasn't
> able to fount any
> project involving some hardware extension.

Several options have been talked about, but the only one I've seen documented
was the DAB radio one soldered to the USB port.

> >> is there a point where to take power near there (the debug connector
> >> doesn't export it...
> >
> > R4701 and R4702 next to the debug connector have one end on the IO 3.3V
> > line, but may not be a good place to pull power from. R7802 on the other
> > side of the speaker has the 3.3V supply for the accelerometer which may
> > be better. It probably depends on your power supply requirements though.
> >
> > I assume you've found the schematics:
> > http://downloads.openmoko.org/schematics/GTA02/
>
> Yes, we have the schematics, but we really miss a good hardware hacker
> between us :)
> the 3.3V supply seems fine. le'ts give it a try. we have to give power
> to an OPAMP.

That doesn't narrow the requirements  down much ;-) What is it you're trying
to do?

> I didn't check if the soundcard is easily reachable, but we may
> substitute the ADC on the
> external sensor with it (opamps are always needed to get a bigger signal).

Could be an option, again depending on what you're doing.

_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware
Reply | Threaded
Open this post in threaded view
|

Re: where to connect for extension ?

Alessandro Sappia
On Sun, Nov 23, 2008 at 1:40 PM, Al Johnson
<[hidden email]> wrote:

> On Sunday 23 November 2008, Alessandro Sappia wrote:
>> On Sat, Nov 22, 2008 at 11:46 AM, Al Johnson
>>
>> <[hidden email]> wrote:
>> > On Friday 21 November 2008, Alessandro Sappia wrote:
>> >> Hi
>> >> Me and some friends wants to connect the freerunner to some kind of
>> >> sensor. We saw that the debug connector give us the SPI bus.
>> >> is it a good choice ?
>> >
>> > It has been suggested in the past. I don't know if anyone's actually
>> > tried it yet though.
>>
>> which ones are the connection used in some other projects ? I wasn't
>> able to fount any
>> project involving some hardware extension.
>
> Several options have been talked about, but the only one I've seen documented
> was the DAB radio one soldered to the USB port.

We want the USB port free, even if going on USB will be easier for us.

>> >> is there a point where to take power near there (the debug connector
>> >> doesn't export it...
>> >
>> > R4701 and R4702 next to the debug connector have one end on the IO 3.3V
>> > line, but may not be a good place to pull power from. R7802 on the other
>> > side of the speaker has the 3.3V supply for the accelerometer which may
>> > be better. It probably depends on your power supply requirements though.
>> >
>> > I assume you've found the schematics:
>> > http://downloads.openmoko.org/schematics/GTA02/
>>
>> Yes, we have the schematics, but we really miss a good hardware hacker
>> between us :)
>> the 3.3V supply seems fine. le'ts give it a try. we have to give power
>> to an OPAMP.
>
> That doesn't narrow the requirements  down much ;-) What is it you're trying
> to do?
>
>> I didn't check if the soundcard is easily reachable, but we may
>> substitute the ADC on the
>> external sensor with it (opamps are always needed to get a bigger signal).
>
> Could be an option, again depending on what you're doing.

we're playing with life signals (aka heart rate)

An OPAMP connected to the 16F818 which talk SPI over the debug connector..

oh... do you know where to buy some unit of the flat cable sold with
the debug board ?


--
Alessandro Sappia
[hidden email]

_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware
Reply | Threaded
Open this post in threaded view
|

Re: where to connect for extension ?

Harald Welte
In reply to this post by Al Johnson
On Sat, Nov 22, 2008 at 10:46:09AM +0000, Al Johnson wrote:
> On Friday 21 November 2008, Alessandro Sappia wrote:
> > Hi
> > Me and some friends wants to connect the freerunner to some kind of sensor.
> > We saw that the debug connector give us the SPI bus.
> > is it a good choice ?
>
> It has been suggested in the past. I don't know if anyone's actually tried it
> yet though.

WE were using the SPI on the debug connector internally at Openmoko at some
time ago to attach a SPI flash to the debug board.  So the SPI on this port
(including the connection to the 2x5pin header on the debug board) clearly
works and is verified.

> > is there a point where to take power near there (the debug connector
> > doesn't export it...

the debug connector FPC traces are too thin for providing power.  They cannot withstand a lot of power, and we would risk frying the FPC in case of a short circuit

--
- Harald Welte <[hidden email]>                  http://openmoko.org/
============================================================================
Software for the world's first truly open Free Software mobile phone

_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware