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[ROM][4.4.4][F2FS/EXT4] AutoDroid 1.2

OP michiil

20th January 2015, 05:12 PM   |  #111  
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I did have power issues until I got the voltage to 5.3V at the plug. USB devices are designed to change their charging rate to adapt to what's supplying it. If the voltage drops, it reduces its requested current until things stabilize, so that way it won't draw more current than the adapter is designed to supply. I've noticed that most USB charging devices won't take full current unless the voltage is slightly higher than a regular USB port (and so it knows it's on a dedicated charger supply). Mine won't take enough power to charge while running unless the voltage is above 5.25V (at the plug) during use.

I'm estimating at the plug voltages since I can't really measure that easily, and of course there are some losses in the cable.

The supply definitely turns on when the ignition is on, and off when it's off, but the Nexus gets really confused. It may be because the car pulses the voltage supply when I turn the key briefly before coming on. It's clearly confused when it gets pulsed. When I have the key in the accessory position, then start it, the car interrupts power briefly. That confuses it into thinking it needs to turn off when the car is running. I hate that. Once it starts turning off, even though it waits a few seconds, it seems to continue to turn off even if it gets power back.

I'm running Multirom, so I switched back to Timur's Rom this morning, but I remembered now I have an issue where the left channel is weak. It's clearly software since it doesn't do it in Autodroid. What a pain. I'm getting frustrated. I'll see if I get pausing and the other issues with Timur's rom though. Clearly there is a lot of R&D associated with making a Nexus into a stable head unit! I was thinking that Android would be more stable than windows (for a carputer), but I'm wondering now (flame suit on .
21st January 2015, 04:46 PM   |  #112  
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Poxin, I want to thank you for bringing this to light! Now that I think about it, that's exactly what's happening with mine. I liked Autodroid a lot, but after switching it showed sluggish performance when turning off, and paused music all the time, etc. I switched back to Timur's rom yesterday and NO PAUSES! Yeah! And, it shuts down much better.

I'm not sure if it's trouble free when switching on and off quickly (like when I turn the key from accessory and then crank the engine), but at least now it aborts shutdown when power is reapplied.

I found the left channel problem, somehow the Poweramp balance knob got bumped. oops. easily fixed. Now it works great!

Thanks!
21st January 2015, 05:07 PM   |  #113  
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Kman9:
The power cycling when starting the car is an easy fix ($10-$15). Just power the DC-DC converter from the constant 12v of the car. Run the DC-DC converter output through a relay (the normally open contacts), then power the coil of the relay by the ignition 12v. Choosing the relay is the only "thinking" part of this modification. Since you need to delay the opening of the contacts (that are closed when you are in ACC or run) when the car is started, you will need a time delay circuit in the "fix.". If you are handy with electronics, just use a 555 timer circuit for the relay (design it so you can easily adjust the time to your preference). If even a supper simple 555 timer circuit is too much for you, then just choose a relay with a high impedance coil and add a capacitor across the coil to hold it closed for a few seconds (the capacitor will need to be isolated from the ignition 12v with a diode, otherwise other accessories will suck its voltage and it cannot do its job supplying voltage to just the coil).

As far as "I'm estimating at the plug voltages," why estimate? Open up the cable near the miro-usb plug (within an inch or two, don't cut the wires, just remove the outer insulation), then you can add permanent pigtails from the red and black wires and run through to a connecter that you can access whenever you want (or for $1.50 you can get a self powered volt meter from China and leave it connected permanently). Alternatively, if you do not want permanent pigtails, just (carefully) stick a pin in the red wire (through the insulation) and a pin through the black wire (again up near the plug) and measure the voltage drop at full load (i.e. when the tablet is needing 2A+). If you use the pin method... After you get your numbers, remove the pins, close everything back up, and make sure there is absolutely no chance that any wires are exposed and that the positive and negative and the ground wires are all intact (no broken strands and no visible wire). Alternatively, if you are rooted, I have to believe that someone has an app that would let you measure the input voltage at the input (not just battery voltage), but I have not looked for one. Obviously this number is available to the firmware, because that is what controls the N7's internal supply that makes batter charging decisions. A third, and MOST PREFERABLE method to fix the voltage drop issue, is to just make a custom cable that uses 16ga or 18ga wires for the positive and negative feed right to the miro-usb connector, then you have no voltage drop!

The problem with the voltage drop is that it is NOT consistent. The drop is dependent on the current and that is constantly fluctuating. The N7 is perfectly happy with 5.3 volts (if that is actually what you have, but unless you measure it who knows), but if 5.3v is what is needed at 2amps, then, depending on you voltage drop, the voltage might be as high as 6v with no load. The N7 will protect itself from over voltage, but in doing so, it may shut off. (or go on battery). Since it is not drawing current from the supply the voltage will remain too high until you shut off the car, and start the whole cycle over again.
26th January 2015, 10:04 PM   |  #114  
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Thanks SaraOB! I'm an EE, so I've thought about several possibilities to supply power to the tablet that aren't so easily pulsed. My favorite is a microcontroller controlled power switch that has a shut off after a certain amount of power draw, not time (millamp hours), but so far what I have seems to work fine, even if pulsed.

What I might do long term is make the tablet turn on when the door is opened, like the new cars do. Then it would be ready to play when I'm ready, not after it takes a few seconds to come on, connect, etc. as it is now. My only problem is that I don't have the luxury of a seat switch (to know when the driver is present). I guess I could turn it on when either door was opened, and then if nothing happened for 60 seconds or so, turn it back off.

16 gauge cable obviously still has loss, but yes it would be substantially less than the tiny 28 gauge or so wire some plugs are attached to. So far mine is charging just fine, so I'm O.k. with estimating. I know my power supply puts out about 5.45V, so it's not going to get higher than that. I don't want to puncture insulation. Long term this causes wire corrosion in automobile environments, and there's not a lot of wire there, so I'm O.K. with estimation.

Thanks for the tips!
28th January 2015, 05:27 AM   |  #115  
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Fastcharge
I can't seem to get fastcharge to work.
I have enabled fastcharge option in Power Event Manager, and everything else works fine (host mode, powerdown and deep sleep on power loss).
When using my stock 2A wall charger, the tablet is drawing ~650mA in host mode (using y-splitter cable) and ~850mA in normal mode.
Any ideas of what the problem may be (software or hardware) ? Should i try different kernel or could it be my splitter cable?
17th February 2015, 10:18 PM   |  #116  
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I have bought me the ezreal usb gauge and i see all the kernel has not helped.
http://www.amazon.de/EzReal-Multimet.../dp/B00KGNFGQ4

My answer was the loading over the pogo pgio pins from the dockingstation.
http://forum.xda-developers.com/show....php?t=1800099
Now i loading with 2Ampere the Nexus 7.
20th February 2015, 06:34 AM   |  #117  
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I too have had a fair share of charging issues and my attempts at addressing that including: taking the tablet apart and wiping the USB port/cable assembly with IPA, soaking the thing in vinegar + baking soda solution, redoing the battery cable and reseating the said assembly, using a quality 5V2A DC-DC converter, hacking the OTG-y cable and splicing the power injection part with a thicker cable, a 6V2A DC-DC converter, adding a 120mm fan behind the tablet to help cooling the battery etc. They all seem to have an appreciable effect, but the power drain problem would come back time after time. It really is quite random, would work perfectly on a good day and would drain like hell a few month later.

One thing to note is I had BOTH hardware AND software issues. The software ones were less frequent but very significantly more severe when present - had a media scanner stuck on a mp3 file that was corrupted, some new wakelocks were added / existing locks toggled back off without me ever being notified. I am using an indigenous gps-only (no A-gps) turn-by-turn nav that used to drain the battery real bad even after force killing the process and turning the GPS off - still haven't figure this one out. Hardware ones otoh are less apparent but are harder to identify. Now that I think about it, it could have been the USB port assembly being oxidized again as I didn't have anything to protect the metal bits after stripping the oxide off of it. Last but not least, it could be the battery. 3C battery widget says it is in good health but who knows.

If the devs are still checking this thread, I have one suggestion to make. Unless I am mistaken, double tap to turn off the screen feature seems to be on by default; I can't find a way to turn that off in the settings. The screen doesn't turn back on by double tapping it (and understandably so, you wouldn't want anything running in the background to "listen" to an incoming double tap), and that's a huge PITA as I am prone to double tap inadvertently, only to be forced to take the tablet out from the enclosing bezel to access the power button to turn the screen back on. On my CM11 based OPO phone, there is a menu item in the settings to toggle this on and off. I am not even sure if anyone would want this feature enabled if the tablet was to be mounted in a car, but if anything you could add that to the settings if you get a chance.

Thanks a ton, appreciate all the hard work you have put into this!
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26th February 2015, 12:24 AM   |  #118  
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Quote:
Originally Posted by Buratei


If the devs are still checking this thread, I have one suggestion to make. Unless I am mistaken, double tap to turn off the screen feature seems to be on by default; I can't find a way to turn that off in the settings. The screen doesn't turn back on by double tapping it (and understandably so, you wouldn't want anything running in the background to "listen" to an incoming double tap), and that's a huge PITA as I am prone to double tap inadvertently, only to be forced to take the tablet out from the enclosing bezel to access the power button to turn the screen back on. On my CM11 based OPO phone, there is a menu item in the settings to toggle this on and off. I am not even sure if anyone would want this feature enabled if the tablet was to be mounted in a car, but if anything you could add that to the settings if you get a chance.

If you are using a Nexus 7 there is a secret magnetic switch at the bottom right of the display (assuming your buttons are at the top left), if my screen turns off I just touch and remove a magnet away from that position on the screen and it will turn the screen on again (thing is was added for a case to be able to switch the screen on when opened. (there is a video on youtube I think to show this). not a perfect solution but at least it gets the screen back on without removing the tablet
2nd March 2015, 09:26 PM   |  #119  
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Quote:
Originally Posted by Kman9


The supply definitely turns on when the ignition is on, and off when it's off, but the Nexus gets really confused. It may be because the car pulses the voltage supply when I turn the key briefly before coming on. It's clearly confused when it gets pulsed. When I have the key in the accessory position, then start it, the car interrupts power briefly. That confuses it into thinking it needs to turn off when the car is running. I hate that. Once it starts turning off, even though it waits a few seconds, it seems to continue to turn off even if it gets power back.
.

There is a very simple fix for this, you take the acc supply, the one that usually supplies the radio, but this one looses power at cranking, and take the ign supply, this has power when cranking, connect them both to your charger power supply line through 2 diodes to stop the power feeding back to each of the different circuits, get a couple 6A diodes .

Wiring

In this photo the joined side of the diodes with the yellow cable goes to the nexus usb charger, the diodes this way round with the 2 silver bands connected will stop the power feeding back to the other circuit,

The yellow cable that is connected to the yellow/black cable is ign live and power when cranking cable, the red cable that is connected to the other diode (not the red cable that is connected to the same loom as the ign cable) is connected to the radio acc power cable.

Using this method the nexus will always see power when acc, ign and crank is on, and all you need are a couple diodes.

FYI the other red cable is a permanent power supply that goes to the charger through a switch, if the battery gets too low in the nexus I flick the switch and leave it for a few hours and the nexus charges up without the key in the ignition, usually I leave it overnight for a full recharge. Of course I also make sure the screen is off when I do this.

---------- Post added at 08:26 PM ---------- Previous post was at 08:20 PM ----------

Ok, for some reason the photo didnt show up..

If you want to see the photo send me a pm and I will send you a link to it
Yesterday, 07:57 AM   |  #120  
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Hi All,

I have been using autodroid and USBROM for fix install of Nexus 7 in car for quite some years.
But time flies, my nexus 7 is now having big performance issue because of the bad IO I believe.
So I have tried to uninstall and reinstall to gain speed. It only last for 1 or 2 days and the system is not usable again.

autodroid and USBROM are the only ROMs (or kernels) offered OTG + Charge option so there is not much choice here.
Since USB ROM has stopped development and autodroid seems to be the only option.

Our Nexus 7 is very special, that we can use it specifically in car. But with very special weakness as well. It does not trim the NAND and there for slow down like hell. So I am looking for a kernel that support the following features.
1. OTG + Charge
2. fstrim() support
3. F2FS support
4. Fast Charge support
5. OTG USB DAC support

I have tried the AutoDroid 1.2 And it misses only the fstrim function, so I keep having performance issue.
Are there any version of the kernel (nightly or beta) that can do all of above or is there any other option available, please?

Thanks alot for your information.

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