Car charger that can enable dock mode

The cable I had the connector sealed up with solder, so no terribly easy access... and it would have been cramped. Luckily my USB MicroB Plug Breakout Board showed up today.

I tried a quick little experiment by quickly doing an ugly job of jamming in a 619k ohm resistor between pins 4 & 5...


Just the resistor with no power or anything else connected resulted in.


Shorting the data pins did nothing, not that I expected it to until I hooked up power. Adding +5v and a ground got me AC charging & "Car Mode Activated". No sign of the always annoying (at least for just charging in car mode) "USB Connected" & "USB debugging connected" taskbar items.

Due to the crappy GPS I recently picked up a Bluetooth GPS, so I'm thinking about making a custom form fitting car mount for the phone with the GPS stuck to the back. Probably going to tap a small mini USB cable off this breakout board to power the GPS & minimize the number of cables running across my dash. Hopefully an iPad 2.1@ power supply should charge both the phone & GPS off the same wire.

I use Setting Profiles to fiddle with settings or launch programs depending on conditions. One of the triggers can be "in car dock" so hopefully that will work & I'll be using that to kick off car activities.

The car charger from my wife's LG bt earbud makes my cappy go to USB mode... so they do exist. Do you want the pn from the adapter?



Sent from my SGH-I897 using XDA App

USB mode is easy, it's the default unless you short the data pins or put in resistors for dock mode.

Sent from my SAMSUNG-SGH-I897 using XDA App

Required components

• USB MicroB Plug Breakout Board
• 619k ohm resistor (car dock mode)
• A USB cable of some kind to chop up, or another breakout board similar to the first item only female
• 1k ohm resistor (desk dock mode)
• Soldering iron & associated supplies
• A USB power source capable of supplying .75 amps (or more depending on how far you go)

Dock mode (car or deck)

To trip Car (or desk) mode all you have to do is put a 619k (1k for desk) ohm resistor between pins 4 & 5 on the Micro USB connector. Some people have managed to do this by chopping up a cable, but I couldn't with the cable or 2 I had around. The only appropriate solution I was able to find was a USB MicroB Plug Breakout Board which was pretty decent at $4 + shipping.



For just dock mode & no other usefulness (like actually charging), you can see what doing a poor job of jamming the resistor in there for testing gets us.



AC charging

In order to get "AC charging" which goes up to 750ma instead of "USB charging" which only goes up to 500ma, you merely need to short out the 2 data pins (pin 2/white & pin 3/green) on a normal USB cable. Most people find it easy to short them (the center 2) on the big flat rectangular end (Type A) of a normal USB cable. Given my approach with the breakout board I just soldered a jumper across the 2 data pins on the board.

Bringing it all together

To complete things, you just need to hook power up to the breakout board. Pin 1 (red) goes to VCC on the breakout board & pin 4 (black) goes to ground. Soldering on the ground is marginally more difficult due to the resistor already inhabiting the hole.

Now you have a cable with a soldered up circuit board on the end. If you plug this into a USB power supply capable of supplying 750ma or more, as soon as you plug it into the phone, it will charge at the maximum possible rate & trip car (or desk) dock mode. The USB debugging & USB drive mounting icons shouldn't show up either (I'm assuming due to shorting the data pins for AC charging mode).

Software

I use Setting Profiles to fiddle with settings or launch programs depending on conditions. I'm using the car dock trigger to do appropriate things such as turn on bluetooth & GPS kill WiFi, etc. You could also have it automatically launch the soso Samsung Car Dock app or Google Navigation.

Taking it further....

Given how the GPS sucks, I picked up a bluetooth GPS. I'm planning on mounting it to the back of my phone mount. Being rather anal I don't like piles & piles of cables running across my dash.

My solution is to modify my original setup. I've taken a 6" length of mini USB cable & cut away everything but the power cables (red & black). I also got a female micro USB breakout board. I stripped the insulation off of a little over an inch of the power wires. I ran the power wires through the VCC & ground holes on the female board & soldered them into the appropriate connections on the male micro USB board with the data pins shorted & the resistor. I then soldered the now trapped female micro USB board in place.

Here are some photos of the little abomination I soldered up. I then coated everything in some red liquid electrical tape to seal it & protect it for when I get around to the melted friendly plastic mounting cradle (in the next section). Sory about the blury photos, not that impressed with the Captivate's camera & had a hard time cleaning some of the smudges off the lens.



This setup should power/charge both the phone & BT GPS. With the phone pulling 750ma & the BT GPS pulling 500ma, you will need a power supply that is rated at at least 1.25 amps of output. The iPad chargers pump out 2.1 amps, so make good candidates.

Making it pretty & mounting it up

The whole unit will shortly be encased in plastic like jonagpa figured out over on Custom DIY Dock for phones with cases or extended batteries. That should support the fragile setup of boards I have soldered together.

I've picked up the Friendly Plastic & used it on another project to make a bushing to mount a pipe for a solar driveway light on a metal lawn spike. I'll be making the docking cradle here shortly. My only quandary at the moment is related to the mounting holes for my mounting my cradle to the suction cup on the windshield/dash. Will post an update when I make the dock.

Sources:
http://xdaforums.com/showthread.php?t=802937 (General dock/electrical stuff)
http://xdaforums.com/showthread.php?t=906630 (good info on building a custom plastic mount)

I'm not an electrical engineer or anything, just a geek, and these are my findings. I'm not responsible for you electrocuting yourself or your gear, which is a real possibility by playing with hatcheting up power cables & what not. I didn't really figure out much of this myself, just scrounged info off these forums & put it all together. Hopefully I linked to all the major sources of info I've found & used.

Update on the cradle

Well, I melted up some friendly plastic & made a cradle for my phone. Not sure if I'm going to keep my first try as it's a bit tight.

Lessons learned:

• Wrapping your phone in 1 layer of tinfoil is not enough, the cradle turns out way to tight
• Cover up the power/volume buttons, camera lens & speaker grille next to the lens with something stiff & bulky, otherwise you get lumps on the cradle that make it REALLY hard to get the phone out
• Using saran wrap or something clear would prevent you from covering up way to much of the screen accidentally
• Friendly plastic drills ok (leaves lots of jagged twisted bits, but you can cut those off with a knife
• You can not sand or use a dremmel to grind off material, point a power tool at it, and it melts
• You can use a belt sander or dremmel to heat up bits of the dock and then move or remove melted plastic around with your fingers or pliers
• My belt sander is really dirty and makes the nice white plastic look like ass (planning on covering it with bondo for a smooth workable finish & painting, so not really a problem)

I have been thinking about how best to attach the cradle to one of my windshield mounts, but haven't gotten too far. Mostly because I'm not sure if I'm going to try and rebuild the cradle almost entirely or not.

tiuk said:

I've been looking for some sort of called moldable plastic, but didn't know what to search for. is the product called "friendly plastic", and is it found in any stores, or online only? Thanks

Click to expand...

Click to collapse

I checked Hobby Lobby & Michael's here in Colorado Springs, no luck. One of the 2 had Friendly Plastic strips, but they are a LOT more expensive than the granules & not nearly as appropriate for this project. I ended up ordering AMACO Friendly Plastic Pellets, 28-Ounce, Ivory from Amazon online. I got the 28oz bottle & barely made a dent in it after making the dock & wrapping a couple of metal spikes like a corn dog, so you could easily do with a much smaller bottle.

Technically it's called Polycaprolactone and if you look at the Wikipedia article, there are several other vendors for the material out there. I goggled around and found a few price comparisons 'n stuff, then figured AMACO's Friendly Plastic was good enough.

My wife keeps telling me I should get some polymer clay and use that. Most of those require heating to just under 300 degrees in the oven or something, and I don't wan to melt the cables & plugs. Some of it can be air dried/cured I guess, but I'm worried about it distorting, or shrinking. Not sure how flexible it is either. I can squeeze the sides of my dock so far in well over a centimeter with no ill effects. That gives you some good wiggle room to pull the phone out but still get a good grip on it with the dock. Not sure if I could have gotten my phone out when I first molded the plastic on it, as it was, I was pretty scared & had had a hard time getting my phone out the first time.

I decided to melt down my first try and restart from scratch. I wrapped my phone with some 3x5 index cards & taped them tight before wrapping things in tinfoil this time. That covered up the camera, buttons & other divots and gave me the extra little clearance I needed. This one is also a bit short, so I can get a grip on the bottom of the phone & pull it out.

I then applied a thin layer of bondo (bondo is the pink stuff, white/greyish stuff is the friendly plastic) to the dock. The bondo is MUCH easier to sand down to approximately the right shape & smooth finish. However I've found the bondo is also noticeably stiffer, which isn't ideal for gripping the phone. A majority of the bondo was then sanded off in the course of getting the right smooth shape.



I picked up a piece of flat plastic from another busted phone mount, sanded it down to the right thickness & cut the right key holes in to fit the prongs on my good Arkon mount. I then built up about a quarter inch of friendly plastic around the key holes & then stuck the whole thing to the back of the cradle by heating up the plastic on both sides. You can see the GPS dangling off the end of the 6" mini USB cable.



I'm debating how much effort I want to put into getting a nice smooth finish & fixing a couple chips in the bondo before I paint it. We'll see how motivated I am. Probably going to just use some velcro strips to mount my GPS to the back of the cradle.

WARNING!!!

Do not use Friendly Plastic for a car mount.

Today it didn't even make it up to 70 degrees Fahrenheit here in Colorado Springs, and my mount started melting up around the camera hole while attached to my dash in the parking lot at work.

Granted I painted mine black, which will heat it up a little more than a light color, but I'm pretty sure it wouldn't be that much better off & would end up melting soon enough.

Back to the drawing board to figure out what material to try next. May make this one into a desk dock now (will be annoying to have the car resistor in it, may just reverse the 2 resistors & use desk resistors for the car).

Try Dynatron. It's an epoxy type material made by Bondo for plastic bumper repair, but not as runny as epoxy resin. It's also sandable, paintable and resists heat and it's a nice black.

I have a few suggestions for you that will make your dock feel more solid, make it easier to sand and paint and also won't chip. In the end, if done right, it will look like something that came out of a factory.

I use this method to fabricate and modify many things, PC cases, fixing laptop cases, building a laptop holder for my car, home/car speaker cabinets, dashboard modification, keyboards, mouse and tons of other stuff... The possibilities are endless.


Materials needed:

Small, thin pieces of wood, popsicle sticks and toothpicks work well.
Thick gauge, solid copper or aluminum wire.
Short strand fiberglass body filler. Comes in a small paint can with a tube of paste to mix it with.
Pantyhose or nylon/aluminum screen for doors and windows (optional, but will make it much easier to mold it in the shape you want and will provide a nice flat, even surface to apply the fiberglass and make it stick to the wood and wire).
Plastic card (IE: old credit card or something similar) that you won't be using anymore. DO NOT USE AN ACTIVE CREDIT CARD UNLESS YOU NEVER PLAN ON USING IT AGAIN! You have been warned.
Wood glue, hot glue, epoxy (optional)
Sandpaper low grit (80-120) for basic shaping, high grit (400+) for a smooth finish.
Metal files for shaping (optional but highly recommended)


First, build a simple frame for your dock out of thin wood or out of solid thick gauge copper/aluminum wire or a combination of both. The wire is best of you want curved surfaces, you can use both materials if you want... The difference is that you'll have to solder or epoxy the wire together to make the frame while you can just glue the wood using wood glue. Make sure you leave a few (~2-3mm) millimeters of space where your phone will sit as you will be adding the fiberglass filler everywhere on the frame to hide it and make it fit snugly.

Next, take your pantyhose or nylon/aluminum screen, wrap your dock with it and glue it in place so it doesn't move... Next mix up some of the fiberglass filler with the paste (follow directions on the can for ratio) and start applying it with a thin piece of plastic (old credit card or something similar that you will not use again), try to apply it as smooth and even as possible as it will make your life easier when it comes to sanding. Also, don't mix large batches at once as it dries fairly quickly, it's better to mix a small batch, use it all, and mix more to finish the job than to have it harden before you're able to use it all...

After you completely covered your piece in a thin layer, let it dry for about 20 mins (enough so it holds its shape), then repeat over and over again until you get the desired thickness and shape (make sure your phone still fits in the slot after drying and before you apply the next coat, if it doesn't, some sanding with the lower grit sandpaper or a metal file will be necessary)... After you're done applying the fiberglass, let your dock sit for at least 24 hours so it has enough time to cure. Then, all that's left to do is sanding it all smooth with the high grit sandpaper, primer and then paint...

This will make a dock that is fairly light, extremely durable and won't melt in the sun... Oh and depending how well you do the job, it can look like it came right out of a factory.

Also, if you don't use a case on your phone, you can just buy a cheap hard case online and build the dock around that using the same method, it would make fitting the phone MUCH easier and make it fit more snugly.

Another point, if you plan on having embedded electronics in the fiberglass, make sure you insulate it all with liquid electrical tape or something similar as it can be conductive and will mess with your circuits.

Enjoy and have fun!

The problem with using anything other than the friendly plastic is easily getting the right fit by just packing the material around the dock. The Friendly Plastic you just have to smear it on your phone after you wrap it in plastic wrap or tin foil or something. It comes off pretty easily if you make a mistake or what not. Not sure I'm willing to do that with bondo or fiberglass as it would be harder to get off.

Also considering just making this out of wood. hardboard back panel with a couple rails attached to wrap around the sides. I've got a router, so getting a good profile on the side rails shouldn't be that hard.

i want to try this, so I am looking for the parts and I see several different watts ratings.

I know next to nothing about electronics, so how many watts are needed for the 619k, 1k and while I am at it, the 301k(for jig)?

Thanks

Next to nothing. Mine were 1/4 or 1/8th of a watt resistors.

Ohms law.... http://www.the12volt.com/ohm/ohmslawcalculators.asp

Assuming it's putting out 5v (USB voltage, could easily be less) divided by 619000 = 0.00001 amps... 5v times 0.00001 amps = 0.00005 watts of power being dissipated by that resistor.

Even if you take the lowest resistance resistor (the 1k ohm one) which would yield the most current you get 0.005 amps or 0.025 watts, way less than 1/8th of a watt, which is the smallest resistor you're likely to see without getting surface mount stuff that won't really work on the breakout board I was using.

It's been a while, but I think all the math is correct, no guarantees. Best I can guarantee is it worked for me.

Thank you.

Parts are on the way.

If anybody wants to PayPal (Devin.Noel@Gmail.com) $3 to me I can send out 10 619k ohm resistors. Think they are 1/4 or 1/8 watt +-2%. I got 200 from a local electronics dealer (think Goodwill meets Radio Shack) for what I'd have paid online.

I can vouch they are the right ones for the car dock.

ronkoni said:

i want to try this, so I am looking for the parts and I see several different watts ratings.

I know next to nothing about electronics, so how many watts are needed for the 619k, 1k and while I am at it, the 301k(for jig)?

Thanks

Click to expand...

Click to collapse

watts arent 'needed'. The wattage rating is the maximum wattage it can handle. wattage changes with the voltage and/or amperage, depending on how the circuit operates. but you dont need to worry about that. with the math stated in the post under yours, you arent going to come close. voltage and amperage affect each-other and therefore wattage too. Resistance (ohms) is the only constant in ANY circuit. And in this part of the circuit of the USB is a constant 5v in this situation.

basically just worry about the ohms adding up to the correct value.

+1 Remember, this doesn't require USB power. It's actually a very low voltage polling ADC seperate from the USB charging/data circuitry. It's takes millivolts and microamps to perform the operation so everyone's correct.

For material, I am looking into SUGRU. I´m not sure it will hold by its own, but it can be used to cover a harder material as lining, providing a softer fit.

d3v14n7 : Do you think this technique would work on foam? Also, what about wrapping the phone in plastic film (saran wrap) and applying the fiberglass on that?