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#1
I've read about somebody wanting to try this, or perhaps achieved it, but can't find where.

http://www.cpkb.org/wiki/Nokia_N900_pinout

and

http://www.cpkb.org/wiki/Micro-USB_pinout

Using these, the back of the pcb of the n900:



Microusb cable:


* 1 - (black) GND / ground
* 2 -
* 3 - (green) Data +
* 4 - (white) Data -
* 5 - (red) VDC / plus / +5V
* 6 - shield

Using this data:

Is it possible to create a new Microusb connection? Where my microusb connection was, there are no more metal solder points to be able to repair the microusb port.

Unsure 100% of the following:
Line up TX with Data +
Line up RX with Data -
GND with GND

But then where does one obtain the positive voltage (usually 5v). On the cable this is VDC +5v, but the battery positive cannot supply this voltage.VCC according to the link "Common Collector Voltage - main power supply ( usually 5V )". But would this work? the provided link doesnt actually specify where VCC is.

The cable would then be routed to where the microusb was. So I'[d attach a new microusb port, with the cables being soldered from the new microusb port, to the connections above.

edit: I already have a desktop charger. I also use TinySMB to transfer my files to and from pc. The only reason I'd have for doing this is if I want to reflash.

Last edited by Storm_11; 2011-03-24 at 09:32.
 

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#2
http://talk.maemo.org/showthread.php?t=54762&page=2
http://talk.maemo.org/showthread.php?t=45385

Nice to have some good tutorials for the USB fix.

Thanks all
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#3
yep read those. however if you read my post again, ive mentioned i have no metal tracks on the pcb for the microusb anymore. which means i cannot use that area. hence my idea of making a new connection from the areas ive listed above
 
Posts: 69 | Thanked: 53 times | Joined on Aug 2009
#4
That's an fbus or mbus connection, not USB, by the looks of it. I think your best bet is to solder to the red and black components as indicated in this image http://talk.maemo.org/showpost.php?p...3&postcount=12
If you've torn those off too, it's probably too late.

Last edited by patstew; 2011-03-25 at 00:56.
 

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#5
could those rx/tx lines be used as TTL serial? that would open a lot of new areas for the N900.
 
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Posts: 1,411 | Thanked: 1,320 times | Joined on Jan 2010 @ Tatooine
#6
Originally Posted by Storm_11 View Post
I've read about somebody wanting to try this, or perhaps achieved it, but can't find where.

http://www.cpkb.org/wiki/Nokia_N900_pinout

and

http://www.cpkb.org/wiki/Micro-USB_pinout

Using these, the back of the pcb of the n900:



Microusb cable:


* 1 - (black) GND / ground
* 2 -
* 3 - (green) Data +
* 4 - (white) Data -
* 5 - (red) VDC / plus / +5V
* 6 - shield

Using this data:

Is it possible to create a new Microusb connection? Where my microusb connection was, there are no more metal solder points to be able to repair the microusb port.

Unsure 100% of the following:
Line up TX with Data +
Line up RX with Data -
GND with GND

But then where does one obtain the positive voltage (usually 5v). On the cable this is VDC +5v, but the battery positive cannot supply this voltage.VCC according to the link "Common Collector Voltage - main power supply ( usually 5V )". But would this work? the provided link doesnt actually specify where VCC is.

The cable would then be routed to where the microusb was. So I'[d attach a new microusb port, with the cables being soldered from the new microusb port, to the connections above.

edit: I already have a desktop charger. I also use TinySMB to transfer my files to and from pc. The only reason I'd have for doing this is if I want to reflash.
Can you confirm if you managed to do this? I've recently acquired a second-hand n900 with broken USB port, and was wondering if I could add my own port using the connections identified in the 1st pic.

But the question is, where to get the +5 volt connection from?
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#7
IIRC these are debug/UART/serial ports, not USB ports.
Who knows if they're DC5V. You'll need a USB host controller, and not any random pins like JTAG/GPIO.
Although, if they /were/ GPIO, anyone want to try strapping an Eye-fi card to them?
 

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#8
Originally Posted by Hurrian View Post
IIRC these are debug/UART/serial ports, not USB ports.
Who knows if they're DC5V. You'll need a USB host controller, and not any random pins like JTAG/GPIO.
Although, if they /were/ GPIO, anyone want to try strapping an Eye-fi card to them?
Ah, so I'd have to take the connections from where the old USB port has fallen off? Hmmm... shame, as the port appears to have taken some of the board with it - therefore a repair is gonna be very awkward.

Thanks for your answer...
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Posts: 437 | Thanked: 1,469 times | Joined on Dec 2009
#9
Actually, you do get access to the USB connector via these pads.
I managed to charge the battery having +5V and GND connected to a 5V power source.


Please be aware that this is highly experimental and you do this all at your own risk!
By messing with your device in this way you'll for sure loose warranty!
Furthermore, you may damage or even destroy your device!



Having said that, lets move on:

In order for the charging to begin +Data and -Data need to be connected (via some resistor ~2.5 Ohm) prior to connecting the power source.
Else simply nothing happens.

Note: I measured whats going on with the default power supply on +Data and -Data and it showed a resistance of 2.5 Ohm.
I used a 2.2 Ohm resistor and also tried to simply shorten +Data and -Data.
In both cases the battery started charging after connecting the power source.

I attached an image of the pins I used.
Edit: I added my stuff in orange color.
GND of course still is the same.

Please note that:
Originally Posted by joerg_rw
...
Battery minus is NOT GND! Don't use it like that
...
And also have a look at the rest of his post on the second page for much more useful information!
Attached Images
 
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Last edited by Wonko; 2011-05-29 at 14:25.
 

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#10
Hi,
good work, Wonko!
Anybody got a working USB data connection over the pads in Wonkos picture? I tried it, but without powering the device over the USB pads, but with battery. The N900 never appeared in /var/log/messages. Could it be possible, that an USB data connection needs also external USB power? Maybe to activate or power up some controlling chip?

Last edited by lazart; 2011-04-30 at 14:29.
 

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