Does A 5v Gp2x Really Exist?


S

sausage

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Whenever people have been doing USB host projects, there is always some sort or external powering or getting a 5V line from the board inside.

Am I to believe that there is no version of the GP2x that truly has 5V through pin 20 on the EXT port? Apparently this is yet to be proven.

My unit is supposed to be a Second edition Mk2 but only has 3.3v. I hear there are two types: 3.3V and 5V.

Can anyone post a picture of a multimeter test showing 5v on their EXT port? And also a photo of their corresponding sticker under the unit?

I'd like to bed this rumour if possible.
 
I don't believe it is true (though I may be proved wrong). As I said on the wiki, I've asked around and Lithosphere, who has a GP2X made during the supposed 5V era has only found 3.3V on the EXT port. EvilDragon said he'd test some different models when he gets time to finally determine the truth.

I think people assume that just because you can run USB devices with a MK2, it must be 5V. However, I regularly use keyboards, mice, gamepads and flash drives off 3.3V and many work fine (though it's pot luck). Try plugging an empty socket into the cradle/developer board and you'll find even a MK1 will power up whilst plugged in, though USB devices may not work due to the logic on the board (with a home made cable, they work).

Also, GPH deny the change and there have been rumours about changes in EXT that haven't been true (like the JTAG pins being moved, which clearly is false).

Basically, there seems to be very little proof that this is the case.
 
When I built my BoB, there was a discuss in #gp2xdev about this. The wiki said something about 5 volts, but not a single person had seen a GP2X with 5v coming out the EXT port.

The unofficial verdict was that it was just bogus information on the wiki that nobody ever really caught.
 
My MK1 does have a 5V point inside. I use it to power the usb-host connection. However it only provides very little current, so only a few usb memory keys I have work. Most of the time the gp2x reboots itself due to the voltage dip when plugging something in.

The 5v can be "tapped" from a testpoint (which made soldering a wire very easy) on the back of the pcb (side of the screen)


usb_small1.jpg


usb_small2.jpg


usb_small3.jpg
 
Thanks for the replies, guys, Orkie for helping follow this through and to cheap plastic for the pics + the others as well. I feel confident now to forget the possibility of trying to get 5v out of EXT. It means I will have to follow something like Sprite's project and build the usb port internally taking the 5v from the inside.

Perhaps eventually someone will prove that a 5v exists but I think it is safe to say that it is not to be factored into the wiki information, nor should it be something that can be expected from a standard GP2x.
 
bacteria said:
Cheap-plastic - nice work, looks nice.

How about using a step-up regulator to connect directly to the batteries and convert 3v into over 5v? Just a thought.
Click to expand...
Nah the intention is to use a small keyboard to connect to the GP2X so I can type documents on the train. An internal port is going to be best for me.
 
Last edited by a moderator:
bacteria said:
Cheap-plastic - nice work, looks nice.

How about using a step-up regulator to connect directly to the batteries and convert 3v into over 5v? Just a thought.
Click to expand...
Yes I tried that a while ago (before discovering the 5v point) with a Linear LT1300 ( http://www.linear.com/pc/downloadDocument....035,P1449,D2742 ) but it did provide even less power than using the internal stepup converter (a Maxim chip that provides several other voltages)

Also, despite the %#)! small chip, it wasn't very easy to get verything in:

lt1300.jpg
 
Last edited by a moderator:
How about putting in a couple of small lithium camera batteries; they are about 12-15mm long (or thereabouts), slim, and 3v - 12v each. I am sure there is space to put this/these into the back of the GP2x, even if it means making a smallish hole in the GP2x case to accomodate it. Wire your USB wires to that instead. They are about 1400 mAh.
 
sorry if this sounds stupid but does this mean that a mk1 gp2x could power the cradle? wasn't the reason that it was thought it couldn't power it cause there was that supposed difference in the power coming through the ext port?
 
Try shoving an empty plug (i.e not connected to the wall or to the power supply at all if you have a generic plug) into the cradle power socket, put your GP2X in and turn on. It should at least boot up.
 
jbrodack said:
sorry if this sounds stupid but does this mean that a mk1 gp2x could power the cradle? wasn't the reason that it was thought it couldn't power it cause there was that supposed difference in the power coming through the ext port?
Click to expand...
The GP2X wasn't really designed with the idea of powering anything but itself in mind :)
 
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