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Self Powered USB Host on the Touchpad

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OP ften

ften

Android Apprentice

  • 29 posts

Posted 13 May 2012 - 11:38 AM #1

http://www.youtube.com/watch?v=0V1Ezi4ADms
(See final build pics below)

WARNING: This could fry your Touchpad if you set this up wrong.

5v Step Up Link: http://www.sparkfun.com/products/8290

I attached the 5v step up's (The step up is used to increases the battery's voltage from 3.7v to 5v) in directly to the battery, the step up's out to a USB extension cable and then the extension cable to the USB OTG adapter. Works great.

It's a little ugly right now, but really all I have to do is move the 5v step up to the SIM card slot (which in most Touchpads is not used) and attach a female micro USB port (a standard USB port is too large for the SIM slot) to it and then modify a Y cable with a male micro USB port.

The only downside of using this step up is it only supports 300mA, not the standard 500mA, so some devices may not work properly. Keyboards, flash drives and mice should have no issues.

Update: Final Pretty version
http://www.youtube.com/watch?v=MaI0QdFd7xk
I cleaned it up and made it pretty, here are some build pics.
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I had to sand the micro USB PCB to fit it in the SIM slot. Sparkfun part number: 9614
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Side shot to show you about the width you need to sand it to so it fits in the SIM slot snuggly.
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Placement of the 5v Step Up.
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Placement of the micro USB PCB.
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Side shot of the SIM Slot with the micro USB in it.
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My modified male micro USB Y cable connected. The Y cable is just a Charge only micro USB cable attached to a USB extension cable.

Edited by ften, 16 May 2012 - 05:40 AM.

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mastamind518

mastamind518

Member

  • 22 posts

Posted 13 May 2012 - 12:40 PM #2

Wow looks good. How did you get the 5v connection from the battery? Is there a tutorial for that somewhere? I assume you have to open it up?

Sent from Touchpad running CM9
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Razor512

Razor512

Android Apprentice

  • 88 posts

Posted 13 May 2012 - 01:40 PM #3

have you tested the effects on the battery level detected by webos and android? webos seems too rely on stored info to measure the battery (usually webos will read a higher percentage battery than android so there is evidence that the OS has it's own way of reading the battery)

does prolonged power draw that the OS cant measure impact the battery readout in a way where it will shutoff before hitting 0%?
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OP ften

ften

Android Apprentice

  • 29 posts

Posted 13 May 2012 - 06:30 PM #4

Wow looks good. How did you get the 5v connection from the battery? Is there a tutorial for that somewhere? I assume you have to open it up?

Sent from Touchpad running CM9

The 5V Step up changes the battery's 3.7v into 5v.
There isn't a tutorial really, but I suppose i could write one in the next few days.
Yeah I opened up the Touchpad and disassembled the majority of it to get the the battery connector to wire the step up, as it is on the underside of the motherboard.
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OP ften

ften

Android Apprentice

  • 29 posts

Posted 13 May 2012 - 06:32 PM #5

have you tested the effects on the battery level detected by webos and android? webos seems too rely on stored info to measure the battery (usually webos will read a higher percentage battery than android so there is evidence that the OS has it's own way of reading the battery)

does prolonged power draw that the OS cant measure impact the battery readout in a way where it will shutoff before hitting 0%?

I haven't done any type of battery drain testing yet, I'll take a look at that tomorrow and see if it shutdown properly when the battery gets low.

Edit 5/14 2am EST: Testing this now in WebOS, although my battery is full so it will take a while to drain it to see how and when it shuts down.

Edited by ften, 13 May 2012 - 10:06 PM.

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OP ften

ften

Android Apprentice

  • 29 posts

Posted 14 May 2012 - 02:57 PM #6

have you tested the effects on the battery level detected by webos and android? webos seems too rely on stored info to measure the battery (usually webos will read a higher percentage battery than android so there is evidence that the OS has it's own way of reading the battery)

does prolonged power draw that the OS cant measure impact the battery readout in a way where it will shutoff before hitting 0%?

I tested the low battery shutdown feature using a USB drive and then having ping echo to a file on the USB drive to keep it in constant use, both Android And WebOS shutdown properly with zero battery percentage left.
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OP ften

ften

Android Apprentice

  • 29 posts

Posted 14 May 2012 - 11:52 PM #7

I cleaned it up and made it pretty, see main post for pic updates.

Edited by ften, 15 May 2012 - 09:12 AM.

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Razor512

Razor512

Android Apprentice

  • 88 posts

Posted 15 May 2012 - 01:52 AM #8

cool, looks pretty good.

if the touchpad were a little bit thicker, I wonder if there would have been a way to install a full sized USB host port that used the data pins from the charge port and allowed a device to be plugged directly into the side of the touchpad.
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childofthehorn

childofthehorn

ResiDEV 3V0

Posted 16 May 2012 - 10:20 AM #9

It does look good.

I would suggest that you do go back and track the USB data lines and reroute those as well. That way you would have a USB host port and a USB data out port.

Realistically, you could fit a full USB port there, it just has to be a hybrid half port (think those USB sticks that have no pin covers). Essentially, you take off the metal shield of the full USB port and just use the bottom piece. The pins are large enough for direct soldering (even in a surface mount package). Actually, I might have to do this. Need some double stick tape for putting it back together first. I has a PCB mill...hmmmmmm
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Rusnak-COBRA

Rusnak-COBRA

Average Android

Posted 16 May 2012 - 11:54 AM #10

with that FULL USB port you are right. I think that it could be possible to make even for those with metal shield. if you will get USB female connector inside, just to the cover, and on one side of SIM slot do a 2mm bigger place for plugging full usb port with shield. hm, maybe i can do that too.

Data pins would be great if so :D but... i wold rather like to have there a SIM card slot, a real one, even if half-self-made
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Rusnak-COBRA - Nokia, Symbian, MeeGo & webOS lover
Nokia N950, N9, E7, Lumia 800; HP TouchPad