# Self Powered USB Host on the Touchpad



## ften (Aug 26, 2011)

(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
[media]http://www.youtube.com/watch?v=MaI0QdFd7xk
I cleaned it up and made it pretty, here are some build pics.








I had to sand the micro USB PCB to fit it in the SIM slot. Sparkfun part number: 9614








Side shot to show you about the width you need to sand it to so it fits in the SIM slot snuggly.








Placement of the 5v Step Up.








Placement of the micro USB PCB.








Side shot of the SIM Slot with the micro USB in it.








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.


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## mastamind518 (Nov 8, 2011)

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 (Aug 22, 2011)

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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## ften (Aug 26, 2011)

mastamind518 said:


> 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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## ften (Aug 26, 2011)

Razor512 said:


> 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.


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## ften (Aug 26, 2011)

Razor512 said:


> 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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## ften (Aug 26, 2011)

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


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## Razor512 (Aug 22, 2011)

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 (Oct 13, 2011)

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 (May 16, 2012)

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  but... i wold rather like to have there a SIM card slot, a real one, even if half-self-made


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## ften (Aug 26, 2011)

Even without a metal casing on the standard female USB port, a full size male USB wouldn't be able to plug in, unless you stuck the port all the way out of the side of the SIM port, which would then risk damaging it.

I did think about wiring the SIM micro USB port with data, but I figured that I would need a micro to standard USB port adapter anyway, it was just easier to go with a Y cable.


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## zbanded (Jun 11, 2012)

It's been near a month now since this topic was last spoken about. I would like to ask (ften) again How did you get the 5v connection from the battery? Is there a tutorial for that somewhere? I know that you would likely have to open your HP Touchpad so I wanted to offer an alternative. Do you think that you could possibly go to Google Picutres and google a pic of HP Touchpad Breakdown search for the pic and the spot where you made the connection and then be able to complete the tutorial. I myself would love to perform this hack on my HP Touchpad also. I'm sure that others like myself would not hold you responsible since we are asking you to complete the information so others also know how to do this. This is an extremely useful hack especially for techs.

Best regards.


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## macauman (Jan 19, 2012)

is it possible to hook up the 5V directly to the default micro usb port?


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## ften (Aug 26, 2011)

zbanded said:


> It's been near a month now since this topic was last spoken about. I would like to ask (ften) again How did you get the 5v connection from the battery? Is there a tutorial for that somewhere? I know that you would likely have to open your HP Touchpad so I wanted to offer an alternative. Do you think that you could possibly go to Google Picutres and google a pic of HP Touchpad Breakdown search for the pic and the spot where you made the connection and then be able to complete the tutorial. I myself would love to perform this hack on my HP Touchpad also. I'm sure that others like myself would not hold you responsible since we are asking you to complete the information so others also know how to do this. This is an extremely useful hack especially for techs.
> 
> Best regards.


I used a 5v Step Up from Sparkfun, which I connected directly to the battery terminal. Basically it takes the 3.7v power from the battery and changes it to 5v. I've circle in red the points that I solder the IN side of the Step Up to the motherboard.









5v Step Up labeled;









Macauman: You could solder the 5v/ground lines to the default micro USB port but you would have to add diodes in-between the port and the step up to prevent electricity from flowing back into the out of the step up when you were charging the Touchpad.


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## macauman (Jan 19, 2012)

ften said:


> Macauman: You could solder the 5v/ground lines to the default micro USB port but you would have to add diodes in-between the port and the step up to prevent electricity from flowing back into the out of the step up when you were charging the Touchpad.


So, a simple diode will simply do the job? And I have one more question. If I set up like that, will there be a charging loop: Battery --> 5V step up --> micro USB --> charge up the touchpad (back to the battery)

Sorry if I didn't explain clear enough


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## childofthehorn (Oct 13, 2011)

Its essentially a flyback transformer.

The sparkfun one you used would not be my choice. I would use one more designed for that kind of purpose:

http://www.sparkfun.com/products/10255
* LiPower - Boost Converter*

The LipoRider from SeeedStudio would also work if you remove some of the connectors. 
http://www.seeedstudio.com/depot/lipo-rider-p-710.html?cPath=155

Both of those will spill out about 500ma when needed (more than enough to charge or use any accessory... even portable HDDs!). They are current boosted, so they will only put out what is asked of them.

Sweet huh?


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## ften (Aug 26, 2011)

childofthehorn said:


> Its essentially a flyback transformer.
> 
> The sparkfun one you used would not be my choice. I would use one more designed for that kind of purpose:
> 
> ...


Very sweet, don't know how I missed that on Sparkfun. I might actually switch out the one I used with this one.


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## childofthehorn (Oct 13, 2011)

ften said:


> Very sweet, don't know how I missed that on Sparkfun. I might actually switch out the one I used with this one.


I would also just use a dremel to cut off the extra space given for the connector. Scrape off those thick traces to get your contacts. Save space!

Pick up some of this while you are at it: http://www.ebay.com/...5#ht_500wt_1413

28AWG silver plated teflon stranded wire. More durable, great power and data transfer....best of all it is easy to use and will take up almost no space. Power transference is much closer to the spec for chassis wiring which is up to 1.4amps for that short of a distance.

Get those data lines transferred while you are at it. BTW: What double sided tape did you use to put it back together?


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## loofkid (Oct 13, 2011)

Is there theoretically a way to make the second usb port essentially a second otg port? I ask because I'd really like to be able to charge the tablet while using something plugged in OTG. On a related note, could this be used to add a MicroSD slot as well?


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## aadelman (Aug 9, 2012)

What would be really cool is to take a 32 GB or bigger USP Thumb Drive, take out the innards, and hardwire it into the touchpad as a second USB drive that is internal.









Has anyone done a step by step guide to installing the power port and making the Y cable?


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## amkaos (Oct 18, 2012)

hi:

i follow this project close

i look foward to the progress and hope it has not been abandoned..

thanx


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## autobulb (Oct 25, 2011)

Is there a way to do something like this with an external battery pack? I don't really want to open up my Touchpad (just yet) and mess around with stuff inside. But it would be nice to be able to carry around the OTG splitter cable and a battery pack that has the appropriate voltage so that when I want to view my camera's photos I can plug in and view it on the nice screen.


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## nevertells (Oct 29, 2011)

autobulb said:


> Is there a way to do something like this with an external battery pack? I don't really want to open up my Touchpad (just yet) and mess around with stuff inside. But it would be nice to be able to carry around the OTG splitter cable and a battery pack that has the appropriate voltage so that when I want to view my camera's photos I can plug in and view it on the nice screen.


You just answered your own question. Watch this video and just substitute the external battery pack to provide power.


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## MidnightRob (Oct 29, 2011)

I have my touchpad working with usb-host mode but I have an issue. Everything works, however I'm curious if there's anyway to unmount the external harddrive someway. Es file explorer wasn't able to do it and if i hard pull it, the files no longer show up when I plug it back in unless i do a shutdown/restart. The external harddrive is formatted under fat32 so any help would be appreciated.


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## Dubi (Jan 19, 2012)

try this
http://rootzwiki.com/topic/33033-otg-usb-insufficient-available-bus-toolthingy/


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## ften (Aug 26, 2011)

Mpgrimm2 has done a much better version of this hack using a full size port and having the secondary port fully working for USB Host devices.

Pictures and walk-through at SDX;
http://forum.sdx-dev.../?topic=20683.0


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## Mpgrimm2 (Dec 6, 2012)

I now have an account here too if anyone has questions and may repost it here if anyone is interested.

Edit: Reposted it here since I am on this site regularly now also ...
http://rootzwiki.com...-size-11-30-12/

Sent from my "Up all night, sleep all day" HP CM9 Touchpad


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## royalr47 (Jan 26, 2013)

Why exactly do you want to do this? Does this enable you to use flash drives and external hard drives? What is the purposes of this mod? You can respond to [email protected]
Thanks for ne info you can supply.
Randy

Ps running CM-10 and am very happy with it. I am not a novice.


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