Host Cable Filter

[NoZ]

Im not too sure on how to wire up the filter. Ive got the 33 Ohm Resistors in place but where to put the 15k Resistors is puzzling me.

Do I wire them like this.

-----------------------
---[33]----[15k]-----
---[33]----[15k]-----
-----------------------

 

[rememberthe8bit]

Well, Sprite has some instructions on how he did his internally, this would be the same as building your own cable.

Hope this helps,

 

[sehs33]

Edit: Sorry, wrong topic.

 

[nubie]

Im not too sure on how to wire up the filter. Ive got the 33 Ohm Resistors in place but where to put the 15k Resistors is puzzling me.

Do I wire them like this.

-----------------------
---[33]----[15k]-----
---[33]----[15k]-----
-----------------------

No.

GROUND
|
|
[15K]
|
|
GP2X USB---[33]----------------------|----------------------USB Device Plug

GP2X USB---[33]----------------------|----------------------USB Device Plug
|
[15k]
|
|
GROUND
​

That is what the little upside-down trees mean, Ground.

http://wiki.gp2x.org/wiki/Image:Bob_usb_filter.png

See my thread on how I did it, there are even higher res photos too: http://www.gp32x.de/board/index.php?showtopic=34309

I hope you get it working, by the way, digikey.com has a 497-3086-1-ND in stock for $0.79 that will do that whole circuit and more with only 5 connections (2 in, 2 out and ground), oh, and its a couple mm in size .

I ordered a couple, we will see if it can be done inside the shell on the EXT connector.

 

[dockthepod]

Does host only work on MK2 models?

 

[nubie]

Well, Sprite has some instructions on how he did his internally, this would be the same as building your own cable.

Hope this helps,

OMG that is one ugly hack, and I doubt it would be very compatible.

Does host only work on MK2 models?

No, all models have the USB on the EXT port.

How you power the USB device is the problem, you need 5 volts from somewhere.

 

[NoZ]

Nubie, you rock. I realise my problem now. I was wiring them to the same ground wire.

 

[NoZ]

This sucks, I have it perfectly set up but it doesnt work. Could it be because Im not using capacitors? I was told I dont need them.

 

[henrik]

This sucks, I have it perfectly set up but it doesnt work. Could it be because Im not using capacitors? I was told I dont need them.

Just checking, have you turned on host mode in the setup?

I almost tore my cable apart after 20 minutes of testing because I had forgotten that

regards/henrik

 

[NoZ]

Omfg, I feel like such a retard now. I already tore my cable apart lmao. I didnt realise I had to turn it on. Oh well back to soldering.

 

[Vimacs]

there is/should be only one ground wire on usb, not two.
Its illustrated like that in schematics cause its easier to read.

 

[NoZ]

Ahh screw it. The connector is a bit out of shape now anyway. I still have another one but Ill save it for something else. I wouldnt mind buying a prebuilt cable.

 

[nubie]

This sucks, I have it perfectly set up but it doesnt work. Could it be because Im not using capacitors? I was told I dont need them.

Capacitors may not be absolutely necessary, but have a look at what we are trying to achieve, the higher lines from left to right are higher voltage, the lower lines are low voltage. The signal needs to be clean like this so that the USB chips on each end can tell the difference from low to high.

http://www.ibiblio.org/tkan/audio/millett/...tt_10khz_sq.jpg

This is a messed up square wave:

http://mixguides.com/studiomonitors/Basics/TF-FIG.4A.WEB.jpg

This is what artaylor got on his scope from an incorrectly terminated GP2X USB!!:

http://wiki.gp2x.org/wiki/Image:USB_Scope.png

As you see the voltage doesn't stop and go straight when it reaches the higher spot, it just bounces around. A capacitor stores and releases the energy like a shock absorber for a car, making everything nice and smooth.

I don't think that the GP2X will be able to read that signal very well.

 

[GameGod]

Hmmm, I've got another question for you guys...

According to the EXT port connection diagram ( http://wiki.gp2x.org/wiki/USB_Host_BoB_Schematic ), pins 12 and 11 are unused.
Has anyone tried snagging the the +5V from inside the GP2X and sending it down the EXT connector? (There's at least one unused +5V connection inside the GP2X, I saw it in some guide.)

Thoughts?

 

[nubie]

Hmmm, I've got another question for you guys...

According to the EXT port connection diagram ( http://wiki.gp2x.org/wiki/USB_Host_BoB_Schematic ), pins 12 and 11 are unused.
Has anyone tried snagging the the +5V from inside the GP2X and sending it down the EXT connector? (There's at least one unused +5V connection inside the GP2X, I saw it in some guide.)

Thoughts?

I thought those were the USB 1.1 device pins (http://wiki.gp2x.org/wiki/EXT_Port), of course if you can cut the traces and feed 5 volts onto both pins that would be awesome.