Putting a retired phone to use...
 

*incoming wall-of-text*

Been meaning to do a write-up on this for some time before the details disappear from my beer-addled brain, but who knows how much I will remember.

After several upgrades to our phones over the years I've ended up with a few Android phones laying around. My wife and I got the original HTC Evo 4G when they came out and they're pretty decent phones still. I of course rooted mine immediately and used different roms constantly in the 2 or so years that I used it. It's been "retired" for a few years now but I still use it for media players, etc. I decided to take my wife's and root it and use hers since her camera lens was pretty scratched up. I think I have a rom on it that is Android 4.1 or possibly 4.2, but I don't think it really matters for my project.

Let's see if I can remember what I have all done on this project. I had a windshield mount for it that when you plugged the phone into it, the phone would charge and also switch into Car Mode. Through some googling I figured out that HTC uses a "sense wire" of sorts on I think pin 3. If it's connected via a resistor to GND it knows that it's in Car Mode and switches it accordingly. I assume if you have a home dock, it would just have a different resistor and the phone would know to go into Dock Mode. Anyway, I think each manufacturer is different, but for my HTC (ymmv) it worked for my needs.

For a while I was just using the phone during my tests right in the dock on the windshield. The problem came in that the battery was old, and with the Jeep off, it wasn't being charged. Also, some of my processes continued to run, (GPS, wi-fi, bluetooth, etc) with the screen off and sometimes they would get all aflutter and the battery would be dead overnight.

I bought an app called Automate-It Pro (I think that's what it's called) where you can set up conditions to control certain things. For instance, here's what I was playing with during my testing....

Jeep not running (basically power off to the phone)
1. Set display timeout to 5 seconds
2. Turn off wifi, gps, etc
3. Kill running applications
4. yada, yada, yada

Jeep running
1. Turn screen on and keep on
2. Turn on wifi, gps, etc
3. Start speedometer app
4. So on and so forth...

This worked pretty well for the most part, but sometimes things didn't shut down correctly and the battery would be toast.

My solution in the end was to completely hack the car dock apart and just use the guts and a separate relay. My wiring isn't at all pretty, but it's been working fine for some months now, and it's hidden out of sight.

The way I have it wired now is so that it's got constant power from the constant-on from the stereo. That way the battery is always being charged. When I turn the key on I get a switched-on 12V, again from the stereo, which fires a 12V relay. When the relay is switched closed, it closes the circuit with the resistor on the sense-wire of the docking station which makes the phone think that it is in Car Mode.

When this happens, the Automate-It parameters kick in.

I think at the moment I have it set so that when it's in Car Mode (key on) the screen gets turned on with no timeout. It also fires up Ulysse Speedometer which has been pretty slick and my go-to speedometer for some time now. There's a paid version that removes ads, etc, but I haven't gotten around to installing it yet because the ads don't annoy me and perhaps I just don't know what the other options are with the paid app. But I digress...

I don't think that I have Automate-It switch anything on or off like GPS, etc, but maybe one of the "rules" I set up just makes sure that they're on. I figured that I didn't need to turn anything off since the battery was always charging.

When the key gets turned off, Automate-It kills the speedometer app and sets the screen timeout to 5 seconds.

I've been using that setup for most of 2014 so far with very few hiccups. Occasionally the GPS won't pick up and the speedometer doesn't work, but sometimes closing the app and restarting it fixes it, sometimes it doesn't, but it's not that big of a deal when I'm just headed to work or the store, I still have the speedo in the dash, even if it's off a bit because of my larger tires.

I also have it wired via the headphone jack to the AUX-in on my stereo, so I can listen to music that I have stored on the phone.

I do have the ability to tether the phone to my current cell phone with a wifi-hotspot, so I have tried out stuff like Pandora and that works well too, and I think that if you wanted to use google maps you'd need an active internet connection, so I could also tether for that purpose too.

Another thing that I have but haven't really played with is a Bluetooth OBDII adapter that I suppose I could use an app like Torque to get some real-time data from the Jeep right there on the phone as well.

Here's a couple pictures of how it looks in my Jeep. I just made something out of some extra wood I had laying around.

Looks like I'm having issues uploading pictures, so I will try to figure that out in another post so I don't lose all this typing. :)

Ok, looks like I just had to resize some of the pics.

haha, had to change my post after seeing pics.. i like it. how deep is mounting pod though? looks kinda deep. is this to allow room for relay, etc.?

Yeah, all of my electronics are stashed back there. I actually took the dummy idiot light plastic out of the dash and the wires are back there. I was going to mount the phone right in the dash where that plate was, but I figured if I ever needed to get the phone out for anything it would be a pain. Now that grey wooden thing is just velcro'd to the dash.

I like it! Wanna set me up with something like that? haha.

Nice. I've been considering using my old HTC One SV strictly for XJ/car use. My biggest issue with that is Google Maps...I'd love to use it for navigation as well, but without an active contract, it makes it difficult. I too could tether to my Galaxy S5, but i think that's too much overhead when I could just use my S5.

I do know that Google Maps has a feature where you can download a map or route for offline use, but I think it requires that you map it out beforehand on a PC or something.

Yeah, if I needed to use navigation, I'd just use my S3. I don't tether to it very often, but it's nice to have the option. Gives me more geek-cred.

There's several Navigation apps out there that allow you to just select a massive area and download it to the device.

For example, I used an Offroad app called "Gaia" to download the entire Southern Half of Kentucky on my latest trip. With zero cell service it works flawlessly. There are on-road apps that do the same. The only issue I've seen with those is that without a cell reception the GPS has a hell of a time recalculating if you miss a turn.