[INFO] HP TP USB OTG Notes, Tips, & Tricks (4-28-14)

[mpgrimm2]

[INFO] HP TP USB OTG Notes, Tips, & Tricks ​

DISCLAIMER: I'm not a dev, nor do I play one on t.v. Use the information and links at your own risk. READ and UNDERSTAND what your doing before flashing is the best bet. I take no responsibility or credit for the information.

This is a work in progress... Still gathering my notes for the thread.

Major Credit to @ramjet73 for working with me on the Evo3d OTG Tips & Tricks thread and allowing me to reuse the info here:
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Other XDA USB OTG related threads:
Spunker88's HP Touchpad USB OTG Compatibility List
Solar powered USB hub (kinda cool)
Nitty gritty OTG hardware discussion
Mpgrimm2's [MOD] Self Powered USB OTG on the HP Touchpad! (v2 Full Size)

For kernels that have On-The-Go (OTG) USB host support built-in, it's very easy to support USB peripherals such as keyboards, mice, flash drives and portable hard drives from your phone regardless of the ROM installed. If you would like more information about OTG, here's a very good thread in the XDA Sensation forum that covers it pretty well.

The commands to mount and unmount USB storage devices manually are covered in that thread, but I've found the easiest way to mount and dismount my flash drive is to use an app called [root]StickMount from Chainfire, the developer of SuperSU. Depending on the ROM installed, it may not be considered compatible and won't show in the Play Store, let me know if that happens and I will post the apk.

If you are using OTG to attach any type of USB devices, please share your experiences and any tips you might have. Also, please use this thread for any questions you might have about OTG support and devices, even if you haven't gotten around to trying it yourself yet.

A couple of quick FYI's about using USB OTG with the Touchpad:

- USB OTG has been possible on the HP TP since CM9 (or earlier?)

- To enable OTG on any android device, Pin 4 (I.D. Pin) needs to be shorted to Pin 5 (DC Return) on the host device. This is the function of "OTG" cables. Note that I have purchased OTG cables that didn't work because Pins 4 & 5 were not shorted/manufactured correctly. On some devices with 3.x Kernels, it is possible to enable USB OTG via a sysfs command (not the TP yet).

- The HP Touchpad is not capable of supplying 5v power out the microUSB port for OTG functions so a standard OTG cable WILL NOT WORK. You must use either an OTG Cable with Isolated External Power Plug, an externally powered USB Hub, or a modified USB Charger/Cable.

- Even though external power is required for OTG, earlier support for USB OTG on the TP would only allow a device that draws/reports 100ma or less (ie USB mouse, small thumbdrives, etc) to be active when directly attached to the primary msm_otg port of the TP (Not Sure if this still applies). This limit can be "bypassed" for larger draw devices (ie portable hard drives) by using an externally powered USB Hub in between the TP's OTG Cable and the device. The hub's "Host" end will report 100ma or less to the TP and allow up to 480ma devices to be plugged into the hub. Good. (Credit to AndroidLover at RootzWiki for this info)

- It is possible to make your own USB OTG Cable with Power, or modify some USB Chargers for OTG functionality if you have some basic soldering skills and equipment.

- Most "dedicated" android USB Chargers have the "Data" pins sorted to tell an android device to use "AC Charging" ("fast charge") instead of "USB Charging". This "prevents data communication and only allows charging. Without a correctly "isolated" OTG Power Cable, OTG will not work with most chargers. Some chargers will either have shorted data pins (i.e. HTC), a low resistance across the pins (i.e. HP) or an "Open" (nothing) across the pins (i.e. aftermarket "Apple" chargers).

- Recommended minimum apps to use with USB OTG:
StickMount, USB Device Info, USB Host Diagnostics, ES File Explorer (or Similar)

 

[mpgrimm2]

Purchase Links for USB OTG items I Use with my TP

I just verified that if you get the Micro USB Host OTG Cable With USB power ($6 from AppleCable on Ebay) that Ramjet73 mentioned (or this one), it will work with any standard USB charger (ie the 1 Amp HTC or 2 Amp HP Touchpad Charger) because the USB Power Connector is Isolated. I also picked up Applecable's USB 2.0 3 Port Hub with data Sync Charger cable for $7

(I may try to modify it to be a USB OTG powered hub with this OTG Adapter and this USB to 3.5mm/1.3mm Adapter to power the hub directly from "ANY" USB charger.
EDIT: It works fine, but modified it anyway).

Here's some updated AppleCable Ebay Store links (4-18-14):
Micro USB Host OTG Cable With USB power
USB 2.0 3 Port Hub with data Sync Charger cable (not OTG, but a cheap hub that works. can be modified for OTG)
Micro USB Host OTG Cable w/micro USB power
Left Angled Micro USB Host OTG Cable w/USB power
Right Angled Micro USB Host OTG Cable w/USB power

 

[mpgrimm2]

USB OTG Cable Schematics. HP TP Needs Cable 2 or Cable 3​

If you are able and want to make your own OTG cable, use the schematic for cable 2 (or cable 3) as needed for the TP.


Here are some pictures of an earlier version I made (Cable 4, not recommended) as an example.

 

[mpgrimm2]

Markmx6's HTC USB Charger/Powered OTG Cable Mod Part 1 of 2 : (Reposted here with permission)​

First off, I am not responsible for you screwing up your phone, shorting your house out, frying your SD card, burning down your home, or anything else that may or may not occur from you building this...

Tools you will need: Razor blade, Soldering iron, Solder, Super glue.

Optional tools: Dremel with cut-off wheel.

I started with components I imagine you will all have, since they came with the phone. The HTC charging cable and outlet adapter.

First, cut around the base of the outlet adapter. This is around 3/16" thick, and the cut is better off to be made on the "shiny" plastic than the "dull" portion. I used a Dremel, but any type of blade will do, it just may take more time.

Make a cut along the white line on the board (Shown in red here) Otherwise this will not work. On typical chargers they short out the Data+ and the Data- connections (mpg2 edit: it forces "AC Charging" mode). Not sure why... Digging a razor blade across this several times should do the trick, but if you want to make sure with a continuity tester that will always give piece of mind.

Now you need to cut your cable, I recommend leaving around 2" or more from the standard usb side. (A little of this wire will come in handy for later in this project)

Cut and then strip your wires, there will be a braided shielding wire just under the insulation. Then it will be helpful to "Tin" the ends of your wires.
The shielding can be completely removed, or you can ground it out, but I haven't found this to be needed.

You will now need to solder the wires to the circuit board. This will obviously need to be in the correct order.

From the top will be:

RED = 5V+

WHITE = Data +

GREEN = Data -

BLACK = 5V-

Now you can re-assemble the Outlet adapter if you choose.


Now you need to cut up the other (phone) end of your cable to enable the OTG function.
Post 2 will outline this.

 

[mpgrimm2]

Markmx6's HTC USB Charger/Powered OTG Cable Mod Part 2 of 2 : (Reposted here with permission)​

Carefully cut down the sides of the connector, if you can do this in one clean cut it will be helpful when you re-attach then after your modifications.

Carefully cut away the plastic, and what looks like hot glue. You need to expose the side that has a blank terminal. and the one on the other side that has a black wire.

Pins 4 and 5 need to be attached, so a small piece of wire (from the leftover ends of the cable comes in handy) works really well.

It doesn't really show up in the pictures though

Now re-glue the pieces from the end of the cable back onto the connector


That is all.


For usb storage you need to have all of the cables hooked up before you insert the SD card.

Sent from my "Up all night, Sleep all day" EVO3D!

 

[mpgrimm2]

I got to looking around and wondering with the parts I have if I am setup for OTG and just need to plug everything together without hacking up a power supply which I'd prefer not to do.
Here's what I have on hand:

I ohmed out the " CrazyOnDigital 2 port charger's" data pins:
Port1-pin3 & port2-pin3 = 0.1 ohms (and about 30k to gnd/shld)
Port1-pin2 & port2-pin2 = 0.1 ohms (and about 30k to gnd/shld)
(I also reversed the leads in case I was reading through a diode)

So it looks like the data pins on this aren't shorted together and that it will function as a Powered USB "y" cable/pass through between ports 1 & 2.


Part 2
I realize that my purchased USB OTG cable won't plug in between the charger & my phone (Schematic #1) so I may use a USB extension Cable and USB A to A adapter that I have (not pictured) or I may just hack a spare USB A to Micro USB (5pin) cable that I have into another OTG Cable.

Q: My understanding is that an OTG cable has the ID pin (pin 4 of the 5pin Micro) tied to Gnd, like Markmx6 did in his original cable; correct? So, that's why the micro USB end gets cut open a bit.
A: Yes.

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My Additional References:

Zoom [DIY] MicroUSB Host Cable

So in a normal micro/mini USB cable, there are 4 wires, 5 pins.
1. Red - V+
2. White - Data -
3. Green - Data +
4. Empty
5. Black - Ground

That micro male to mini female cable above has the 4th (5th?) wire, brown. This is the ID wire. Shorted to ground, it makes the cable a host cable.

Wikipedia's: USB On-The-Go page

The OTG cable has a micro-A plug on one side, and a micro-B plug on the other (it cannot have two plugs of the same type). OTG adds a fifth pin to the standard USB connector, called the ID-pin; the micro-A plug has the ID pin grounded, while the ID in the micro-B plug is floating. The device that has a micro-A plugged in becomes an OTG A-device, and the one that has micro-B plugged becomes a B-device. The type of the plug inserted is detected by the state of the pin ID .

Three additional ID pin states are defined[4] at the nominal resistance values of 124 kΩ, 68 kΩ, and 36.5 kΩ, with respect to the ground pin. These permit the device to work with a USB Accessory Charger Adapter which allows the OTG device to be attached to both a charger and another device simultaneously.[6]
These three states are used in the cases of:
- A charger and either no device or an A-device that is not asserting VBUS (not providing power) are attached. The OTG device is allowed to charge and initiate SRP but not connect.[6]
- A charger and an A-device that is asserting VBUS (is providing power) are attached. The OTG device is allowed to charge and connect but not initiate SRP.[6]
- A charger and a B-device are attached. The OTG device is allowed to charge and enter host mode.[6]

Micro-USB connector pinout

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Part3: SUCCESS! (with Otg Enabled kernel)
I went ahead and modified a spare USB A to Micro B cable for OTG without power. Plugged everything up with my Logitech Wireless USB mouse and it works! Cool as can be! See new pics. (Yellow wire is the Jumper).

Still have a few questions:

Q: Would the "purchased" OTG Cable already have pin 4 & 5 Shorted?
A: YES it should, but one of the cables I bought was defective.

Q: Does your OTG setup from the op charge the phone at the same time (and/or keep it charged)?
A: Yes (Not Likely on the HP TP)
Edit: Apparently I broke the +5v wire during reassembling the cable. See pictures.

 

[mpgrimm2]

My CrazyOnDigital 2 port charger doesn't have the data pins shorted (D+ and D-) like the stock HTC unit. This causes any "Android" device to charge at the lower 500ma Max "Charging USB" rate vs "AC Charging" (explains my slow charging when travelling), but a bonus is that it allows me to pass data b/w the 2 ports like a simple hub.

- If the D+ and D- pins are shorted when an OTG USB cable is plugged in, the phone will go into "AC Charging" mode, but not allow OTG devices to work, but if the phone is still connected and the data pins opened back up, you retain "AC Charging" mode and have USB OTG functions.
(I'm thinking that a simple on/off switch installed across the data pins of my charger will give me a dual mode charger).

---------------------------------------------------------

AC CHARGING / USB CHARGING (Data Pass Through) MOD 12-1-12
​

I am not responsible for you screwing up your device, shorting your house out, frying your SD card, burning down your home, or anything else that may or may not occur from you building this...

- I got tired of having a 2 port 2 Amp charger that only allowed 500ma "USB Charging" with Android & OTG. See pix:

 

[mpgrimm2]

Post 8 for me.

 

[mpgrimm2]

Originally Posted: 2/23/13

Q: Does anyone know for certain if it's possible on the touchpad to echo the OTG "mode" command (ie host vs none) ?

On the evo3d there is a sysfs command that can be "echoed" to enable OTG with any standard cable and I was able to get the Kernel Tuner dev to add a toggle in his app for it.

If I can find someone who knows & can verify the sysfs command for our CM touchpad's I can have him add it into the app easily (Apr2014 Edit: KT not currently in development).
Note: I haven't found it yet by digging around with EsFileExplorer and activating OTG with a cable.

Didn't know OTG could be activated (on the Evo3D) using a standard cable with a sysfs command like:

echo host > /sys/kernel/debug/msm_otg/mode

Options are "host" or "none" (maybe this command can get added to "kernel Tuner" app! ). Wonder if it's the same for the Touchpad.

Fyi, don't know how different it would be on each device (ie GS3 vs. Evo3d & HP Touchpad), but it looks like for the Touchpad on CM9 it's

 /sys/kernel/debug/otg/mode

I realize some may say "why bother, just use an OTG cable", but if you look through my OTG mod thread, you will realize that it's one less wire to solder to a circuit board and will also allow any user to avoid buying the cable.
Note: I also posted this in my [MOD] Self Powered USB OTG on the HP Touchpad! (v2 Full Size) 11-30-12 thread.

In kernels 2.6.39 and newer the sysfs entry is named msm_otg. We're using the 2.6.35 kernel where the entry is named otg. The available options are: none, peripheral and host.
It seems that the:

echo host > /sys/kernel/debug/otg/mode

command should work.

Thank you for the feedback.

/sys/kernel/debug/otg/mode

That's what I was thinking too, but I can't seem to see any change of state at that location when activating it with a shorted ID pin and the developer for Kernel Tuner indicated that he added the code for it which doesn't seem to work either.
When I check the mode file there isn't anything there (blank). I have also tried settings permissions for rwx-rwx-rwx and manually typing "host" and saving the file. It goes immediately back to a blank file.

Admittedly I'm an amateur and was trying to echo it with an /init.d script at one point (edited with EsFileExplorer), shouldn't that work? I will fiddle with it some more.

First of all try to echo from a terminal app on running system and check if it works, check also the dmesg if there's no error there. If it will be working then you can add an entry to init.d script

 

[mpgrimm2]

Last one for me. Feel free to comment.

 

[ConfusedTouchpad]

Trouble with OTG/Touchpad/DS4 controller

I hope someone can help me. I am trying to connect my Dual Shock 4 PS4 controller to my Touchpad via OTG, so I can use Remote Play for my games. I am rooted, using PAC MAN ROM 4.4.4RC-1. Through trial and error (and this forum), I discovered that a normal OTG cable will not work. So, I ordered and received my powered OTG cable in the mail from China (I found the link in this thread a couple of weeks ago). Unfortunately, the HP Touchpad still doesn't seem to recognize the DS4, so I want to make sure I am doing this correctly. Pictures of the cable are attached, along with my setup. The only thing missing from the pix is the connection of the male USB side of the cable to the iPhone wall charger (the cable is very short to get all in one picture). I lost the official Barrel charger 2 years ago, but the iPhone wall charger DOES charge my Touchpad when in Android mode, so not sure why it won't work for OTG connectivity.

1. I connect the DS4 to the micro-USB controller cable that came with the PS4.
2. I then connect the male USB side of that cable to the female USB of the powered OTG cable.
3. I then connect the micro-USB of the powered cable to the HP Touchpad.
4. I then connect the male USB side to the female iPhone wall charger (I lost the TP Barrel charger a couple of years ago).

And I get nothing. The DS4 seems to have no connectivity with the HP Touchpad using this method.

FYI: Again, I am rooted and running Pac Man Rom 4.4.4RC-1

The strange thing is that when I connect the Touchpad to the iPhone wall charger when it's on Android, it charges! So I don't understand why it's not working when connected to the DS4. Is the official Barrel charger the only one that will work? Do I need to install some app or software to get the DS4 to be recognized via OTG?

Any help you can provide would be greatly appreciated!
Thank you!

 

[mpgrimm2]

I hope someone can help me. I am trying to connect my Dual Shock 4 PS4 controller to my Touchpad via OTG, so I can use Remote Play for my games. I am rooted, using PAC MAN ROM 4.4.4RC-1. Through trial and error (and this forum), I discovered that a normal OTG cable will not work. So, I ordered and received my powered OTG cable in the mail from China (I found the link in this thread a couple of weeks ago). Unfortunately, the HP Touchpad still doesn't seem to recognize the DS4, so I want to make sure I am doing this correctly. Pictures of the cable are attached, along with my setup. The only thing missing from the pix is the connection of the male USB side of the cable to the iPhone wall charger (the cable is very short to get all in one picture). I lost the official Barrel charger 2 years ago, but the iPhone wall charger DOES charge my Touchpad when in Android mode, so not sure why it won't work for OTG connectivity.

1. I connect the DS4 to the micro-USB controller cable that came with the PS4.
2. I then connect the male USB side of that cable to the female USB of the powered OTG cable.
3. I then connect the micro-USB of the powered cable to the HP Touchpad.
4. I then connect the male USB side to the female iPhone wall charger (I lost the TP Barrel charger a couple of years ago).

And I get nothing. The DS4 seems to have no connectivity with the HP Touchpad using this method.

FYI: Again, I am rooted and running Pac Man Rom 4.4.4RC-1

The strange thing is that when I connect the Touchpad to the iPhone wall charger when it's on Android, it charges! So I don't understand why it's not working when connected to the DS4. Is the official Barrel charger the only one that will work? Do I need to install some app or software to get the DS4 to be recognized via OTG?

Any help you can provide would be greatly appreciated!
Thank you!

I will hopefully touch base with you shortly. PM sent.

 

[mpgrimm2]

Small update. Spoke over the phone briefly and he was able to get USB OTG working with a USB mouse (had to unplug/replug OTG cable from TP to have it initialize each time) so it looks like he has the basics for a working OTG setup and an OTG enabled ROM.
Might be the version of ps4 controller he is using or the apk/driver that enables it to work.
Hopefully more to come. Anyone else try this setup before? Chime in.

He is on
[ROM][OFFICIAL][KitKat 4.4.4][TENDERLOIN] PAC-man KK RELEASE [WEEKLY]http://forum.xda-developers.com/showthread.php?t=2779954

[NEW][ALL][PORT][4.0+] PS4 Remote Play for Android (New Thread)
http://forum.xda-developers.com/showthread.php?t=3068225



Sent from my LG G4 on Tapatalk.

 

[mpgrimm2]

An confused update

Hi ....just an update following my email earlier:

1. I went to a local PC Repair place and they let me use a 5.3V wall charger, to see if some added juice might be enough to get the DS4 recognized by the TP over the OTG cable. Unfortunately, nothing.

2. I went to Gamestop and they let me connect their DS4 to the Touchpad, to see if it would work (using the iPhone wall charger I brought along). Again, nothing.

3. I don't know how this happened, but at one point during the process, the Touchpad turned completely blue and would not respond to anything. I was able to reboot by holding the Vol button down, plus the other 2 buttons. Freaky.

Maybe this info + my earlier email might help you know what's going on? It doesn't seem like this is going to work for me, but you never know.

Thanks!

Sent from my LG G4 on Tapatalk.

 

[mpgrimm2]

Another thought on the matter,

Last time I dug into OTG TP setup, there was an issue with either the kernel or the msm chipset that prevented it from using any device directly connected to the OTG cable/port that was asking for more than 100ma or so (ie USB portable drives, CDROM's, etc). You would think this doesn't matter since we are providing power externally separate from the TP but it didn't know that.
The work around was to connect a powered USB hub between the touchpad and the device so that the Touchpad sees the low power Hub on its port, and the hub acts as the middle man supplying the full 500ma out to the device, ie the DualShock4 controller.

Got a powered USB hub handy?
See post 2 for a picture of my hub setup.
(I see I mentioned this in post 1 also)

If u want to see the details, you can get USB port and current draw info from the USB Device Info app or USB Host Diagnostics app linked at the bottom of post 1

Sent from my LG G4 on Tapatalk.

 

[ConfusedTouchpad]

Mr. Grimm....as always, thanks for the info. Other than your responses, it's pretty much crickets in here, eh? (Think everyone else abandoned this thread a long time ago).

I am a little confused about your post below. I did see posts #1 and #2, where it was stated that regular OTG cables wouldn't work for the TP, that you need a powered USB one. That's why I bought and tried a powered cable....in fact, there was a link to it in post #2: "Micro USB Host OTG Cable With USB power".

So if I understand your post below correctly, you're now saying I need something ADDITIONAL (power or an additional cable) on top of the one I just purchased? I'm not sure I understand....I thought I had done what I was supposed to. I connected the USB male part of the cable to the iPhone charger, and also a 5.3V wall charger I tried at a PC Repair store and neither would work. The only thing I've gotten to work, occasionally, is the USB mouse connected to the cable. DS4 not working.

Any help would be appreciated....thanks!

Another thought on the matter,

Last time I dug into OTG TP setup, there was an issue with either the kernel or the msm chipset that prevented it from using any device directly connected to the OTG cable/port that was asking for more than 100ma or so (ie USB portable drives, CDROM's, etc). You would think this doesn't matter since we are providing power externally separate from the TP but it didn't know that.
The work around was to connect a powered USB hub between the touchpad and the device so that the Touchpad sees the low power Hub on its port, and the hub acts as the middle man supplying the full 500ma out to the device, ie the DualShock4 controller.

Got a powered USB hub handy?
See post 2 for a picture of my hub setup.
(I see I mentioned this in post 1 also)

If u want to see the details, you can get USB port and current draw info from the USB Device Info app or USB Host Diagnostics app linked at the bottom of post 1

Sent from my LG G4 on Tapatalk.

 

[mpgrimm2]

You MAY need the hub if the Ps4 controller indicates it needs more than 100ma on the USB port. Perhaps you can pick one up at Walmart and return it later if it doesn't work.

- Yeah, I don't think many people actually use or have tried OTG with their Touchpad. So there may not be a lot of traffic here.
Most of my OTG info actually originated from my Evo3D threads because it had the same chipset and processor as the Touchpad.

Sent from my LG G4 on Tapatalk.

 

[ConfusedTouchpad]

Thanks. Is 100ma more than the stock TP barrel charger provides? Maybe I should just order one of those off Ebay, if that will provide the power needed, since I need one anyway after losing it. Is the USB hub more powerful than the barrel charger?

Also, adding all these things makes for a really clunky setup and sadly reduces the convenience of OTG connection. I guess I will have to decide if it's worth it.

You MAY need the hub if the Ps4 controller indicates it needs more than 100ma on the USB port. Perhaps you can pick one up at Walmart and return it later if it doesn't work.

- Yeah, I don't think many people actually use or have tried OTG with their Touchpad. So there may not be a lot of traffic here.
Most of my OTG info actually originated from my Evo3D threads because it had the same chipset and processor as the Touchpad.

Sent from my LG G4 on Tapatalk.

 

[mpgrimm2]

Thanks. Is 100ma more than the stock TP barrel charger provides? Maybe I should just order one of those off Ebay, if that will provide the power needed, since I need one anyway after losing it. Is the USB hub more powerful than the barrel charger?

Also, adding all these things makes for a really clunky setup and sadly reduces the convenience of OTG connection. I guess I will have to decide if it's worth it.

That is not exactly the issue, but you should be using a 2 Amp (2000ma) charger with your Touchpad. 1.8A may work fine though. (Stock is 2.0 or 2.1 Amp I believe)

Regardless of getting 'enough' actual power from a charger to the devices, here is the deal/conversation between the TP's chipset (Host device) and the DS4 controller's usb chipset...

DS4: knock knock. Hi, I'm a device that needs 480ma from your USB port, can you let me in.

TP: From behind the closed door... Sorry, only 100ma or less here.

DS4: But I have my own USB power. [email protected]#%
(TP lets hot little 30ma thumbdrive through, followed but 35ma mouse)

Later... Ds4 comes back with its cute little 75ma Hub friend...

Hub: knock knock. Hi, I'm a device that needs 75ma from your USB port, can you let me and my friends in?

TP: From behind the closed door... Uh, sure you all look like only 100ma or less.

Sent from my LG G4 on Tapatalk.

 

[mpgrimm2]

I don't know many people where I moved to recently but if I can get my hands on a ps4 controller, I can see how thing work on my setup.

Please install those 2 USB info apps I mentioned before, they will help identify what the TP sees on its port:

USB Device Info
USB Host Diagnostics

Sent from my LG G4 on Tapatalk.