Question Abt. Japanese Page Re Bluetooth Mod

[daniel3000]

Hi huys.

I'm considering to upgrade my Zauri with USB Bluetooth modules.
Since I want to keep the hardware compatible with standard kernels and don't want to do too many modifications to the hardware, I'm looking into the simple solution:
Take a normal USB BT module, connect it 1:1 to the USB port with a power switch, which will probably be blocking the USB port when BT is used. This limitation is okay with me.

I think this method is described here:
http://www.piro.hopto.org/~piro/pukiwiki/p...%A2%B2%BD%5D%5D

But since I cannot read any Japanese, would anyone able to read that please let me know how the switch must be connected?
From the pics it seems the switch only switches one line. But which one?
Is it really enough to switch only one line (probably one of the power lines)?
When the data lines are still co nnected to the BT module, can other USB devices which are attached in a normal way to the USB port still work without a problem?


Once I know all this, I will begin with the surgery and take some better pictures to put them onlilne.
I think this is  a great way of enhancing the functionality of a Zaurus!

aTdHvAaNnKcSe
daniel

[pelrun]

You need to switch two lines with a dual-pole (DPDT or DPST) switch. I suggest one pole goes between GND on the Z and GND on the module, and the other goes between GND on the Z and the ID pin in the Z's usb port. Which is next to the GND pin, btw.

If you were to permanently connect the ID pin to ground you would force the Z's usb port to always be in host mode, which will use more power even when nothing is connected.

[daniel3000]

You need to switch two lines with a dual-pole (DPDT or DPST) switch. I suggest one pole goes between GND on the Z and GND on the module, and the other goes between GND on the Z and the ID pin in the Z's usb port. Which is next to the GND pin, btw.

If you were to permanently connect the ID pin to ground you would force the Z's usb port to always be in host mode, which will use more power even when nothing is connected.
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aha thanks...
so then comes to mind:
Wouldn't it be enough to wire the ID pin directly to ground on the module and only switch GND of the Z to GND of the module? That way the switch would interrupt module power AND the ID-GND-connection with just one pin...

Is there any picture or schematic where I can see the pin assignment of the Z USB port (backside, where I can solder)?
Can I solder directly to the legs on the back of the connector?

thanks
daniel

[dproldan]

I have tried something like that with a wifi dongle.
  I used the dual pole approach,  one switch for the ID pin to ground and another switch for +5v (ground on another test) to the dongle,  the rest of the USB pins soldered directly to the pads under the Zaurus' USB connector.

  The dongle worked fine with this setup when I turned on the switch,  but I couldn't make anything else work in the USB connector.  I suppose that when the dongle was turned off,  the USB data lines had some noise or where connected to 5 v or ground.  Maybe it wont happen with another dongle.

 my 2 cents.

Daniel

[pelrun]

Wouldn't it be enough to wire the ID pin directly to ground on the module and only switch GND of the Z to GND of the module?[div align=\"right\"][a href=\"index.php?act=findpost&pid=156225\"][{POST_SNAPBACK}][/a][/div]

Eek!  

Actually, I considered such a plan (that's the real reason I suggested switching GND instead of 5v) but rejected it when I realised it won't work.

ID and Z GND get shorted when a host cable is plugged into the port; that's how the usb host/client detection works. Which would cause the BT GND (already connected to ID) to be connected to the Z GND, and the BT would turn on. *Not* what you want when you already have another device connected

[daniel3000]

Wouldn't it be enough to wire the ID pin directly to ground on the module and only switch GND of the Z to GND of the module?[div align=\"right\"][a href=\"index.php?act=findpost&pid=156225\"][{POST_SNAPBACK}][/a][/div]

Eek!  

Actually, I considered such a plan (that's the real reason I suggested switching GND instead of 5v) but rejected it when I realised it won't work.

ID and Z GND get shorted when a host cable is plugged into the port; that's how the usb host/client detection works. Which would cause the BT GND (already connected to ID) to be connected to the Z GND, and the BT would turn on. *Not* what you want when you already have another device connected
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you are right... too bad :-)
Now I have two switches, one for ID-GND and one for GND to the module.
The module works.
Now testing other stuff.

Any idea how to switch all four (or five) lines using a small component, maybe an opto coupler or somthing like that?
Just one switch on the outside would be good...

daniel

[albertr]

From my short experience with wiring USB modules to Zaurus, pelrun is absolutely right  - ground line needs to be disconnected (not just 5V line). If you will keep ground connected to both modules, it would leak too much current on usb data lines.
-albertr

[daniel3000]

From my short experience with wiring USB modules to Zaurus, pelrun is absolutely right  - ground line needs to be disconnected (not just 5V line). If you will keep ground connected to both modules, it would leak too much current on usb data lines.
-albertr
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Okay, so I should probably switch all five USB lines (or at least four of them, leaving only GND connected to the module, so switching the three other lines to the module and the GND-ID connection).

I'm now looing into Photomos relays for this task.
Of course I could wire four micro switches to the outside, but that seems inconvenient to use. instead, just one switch switching power to the Photomos releays would be more convenient.

However, the only suitable photomos relays (from the electric specs) are quite large... Small SMD ones only have one relay, so four small ones would be needed. Also, the resistance of the sall ones is not acceptable. The large ones have two relays in one piece and a lower resistance...


Albertr or others, do ou have any experiences with such components?

Thanks
daniel

[pelrun]

You don't need opto components at all; they are used for proper circuit isolation when all you need here are simple switches. I would have recommended a bus switch but I believe they would only be suitable for switching the data lines and not the power ones.

If you personally don't see any interference with other USB devices when you're only switching ID and GND, why bother switching every line?

[albertr]

I second that, no need to disconnect 5V or data line, ground will do it.
-albertr