Galaxy Nexus Watering Hole

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  1. nkk

    nkk Well-Known Member

    Look into the Qi charging standard. The Rezound (and TB and IIRC all VZW Chi phones) have two V+ pins and two ground pins. I think (not sure...long time since I looked into it) that the V+ are broken into a ~5V and ~3V (~ meaning approx, not AC obviously) but the circuit limits output to 5V. I think you can ignore the 5th pin and just bridge the two V+ and two grounds and go from there. The four applicable pins (again, IIRC and I have NOT seen the rezound back specifically) are in a squre and the fifth is offset.

    Hope that at least put you on the right track.


    PS in case I did not say this enough, get a darn multimeter and check what I am saying before you go using it with your phone. There is a finite nonzero appreciable chance that I am wrong.

    EDIT: Look at the pic in the OP.

    Those five pins next the uSD slot in a square and one offset. That is what I am referring to.

    EDIT2: Here is a good example of someone doing it with the TB back, which also uses Qi

    jbdan, MSUgEEk and BabyBlues like this.
  2. BabyBlues

    BabyBlues Trouble Just Finds Me! VIP Member

    Well said. Credit should be given where it is due - definitely agree with that. And I understand rules and such about searching first but they, as well as quite a few other sites (I swear I'm not disliking just them), don't make the search mode very easy to use. I will say that right about now I intensely dislike Amazon and their Kindle store and app but that's a whole other issue.
    I have learned from this wonderful place that it is much easier to rise above the nasty and snarky comments IF everyone is willing to work at it.
    EarlyMon, jbdan and Unforgiven like this.
  3. BabyBlues

    BabyBlues Trouble Just Finds Me! VIP Member

    I didn't understand most of that but I had to thank it because your PS made me laugh. :D
  4. Lucky Armpit

    Lucky Armpit Well-Known Member

    I came across a few forums that mention people found relief from the one-way audio issue by turning off Voice Privacy and setting DTMF tones to Long. I'm not exactly sure what Voice Privacy is (encryption, possibly?) or the difference between long and short DTMF tones, but thought I'd ping the wonderful Nexus family and see if anyone has heard of this and/or could debunk the suggestion?
  5. AntimonyER

    AntimonyER AF Addict VIP Member

    I have seen an excellent explanation of this by Early in the GNex forum, if I find it before he posts I will repost it here.
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  6. BabyBlues

    BabyBlues Trouble Just Finds Me! VIP Member

  7. Unforgiven

    Unforgiven -.. --- - / -.. .- ... .... Moderator

    I should have been more clear about crediting and linking to XDA. If I find a post or thread over there that summarily answers a question, I will paraphrase (I don't copy and paste from other forums, paranoia about copyright) and link to the post/thread. If I find a solution across multiple posts / threads I paraphrase the answer and give credit to the smart folks at XDA. Much as I do when I find answers for folks in other threads on this forum (I will hit the quote button and copy and paste that, and as I recently learned, it links back too:D). I am a member at XDA too and they are a very smart bunch whose work I appreciate.
    EarlyMon likes this.
  8. MSUgEEk

    MSUgEEk Well-Known Member

    Yeah, my wife has a Rezound and that's why I was greatly confused when I opened up the back and found 5 pins where the inductive charging circuit contacts were supposed to be. What you're saying makes sense, just gotta figure out which one is which now...kind of difficult since I don't own the inductive charging back...I want to make my own out of my other Palm Touchstone circuit.
  9. MSUgEEk

    MSUgEEk Well-Known Member

    So, NKK, what you're saying is that the top 2 pins are GND and the bottom 2 are a +3V and a +5 V. In reality you need to connect the +3V and +5V to the same +5V source and the 2 GNDs connect together as well.
    Unforgiven likes this.
  10. nkk

    nkk Well-Known Member

    Honestly, given that you seem to need to output 5V and 3V together it seems like it would take a lot of in depth hacking to get a palm circuit to do this. I would see if you could just aply 5V to the 5V pin (after you find it, of course).

    My gut is that that 3V pin is there so that things like tablets, which have two 3.7V Li-Ion batteries in series to provice 7.4V (for larger screen, etc) can use the Qi standard without modification and the standard can stay...well...standard and universal. From that,I would take the preliminary assumption that the 3V is never drawn from, and the 5V pin provides all charge for the phone. Then it becomes a lot easier to reconcile the two standards.

    My only concern is that the person I linked to who did this is the TB bridged the two V+ for a total of 8V, so perhaps the circuit to make 5V is in the phone and wants 8V no matter what, meaning you are probably SOL with the Palm kit, which outputs only 2 pins, 5.6V and gnd.

    On a different note, can you do a quick write up of your case mod? I want to do something similar, but am debating between inductive coil in phone (and then case on phone) or coil in case with the pogo pins also in the case.

    The real question is why Palm felt the need to make their own standard. I understand the economic OEM lock-in aspect, but my God is it annoying.

    Unforgiven likes this.
  11. nkk

    nkk Well-Known Member

    See...this is where I do not know. I think that might work, but I do not know where the circuitry to decide 5V vs 5+3V is. There are a few options that I can think of:

    1) The 3V just goes nowhere in the phone if it does not need all 8V. The thing is, the person I linked to bridged both V+, so he had 8V and it was working

    2) The phone takes in 8V and then the circuit in the phone steps it down to 5V. Thus, the back cover and mat are kept standard across all devices and it is the in device circuit that derives the needed voltage. This is most logical IMHO.

    Option 2 is harder for you to get around, because stepping it down may not work if you only input 5V (it would work if they used a microprocessor to output 5V no matter the input, but that is highly unlikely. The cost would be absurd).

    Option 1 works for you, but you would have to find the 5V pin first.

    There may be other things I am missing. I have not read in depth the spec docs of the Qi standard (although looking there might not be a bad idea. How good are you at reading technical documents?)


    EDIT: just to be clear, the phone does not have +5V pins (because it does not output anything). I know what you are saying, but I just wanted to make sure it was perfectly clear. You want to put +5V onto the (now bridged) pins that would otherwise receive +5V and +3V from the Qi back cover.
    Unforgiven likes this.
  12. Unforgiven

    Unforgiven -.. --- - / -.. .- ... .... Moderator

    Conversations like this make me feel like a noob.:D I'm glad your having it here in the GNex megathread, I learn a lot in here. I can do a lot of electrical stuff, but I would kill everything in sight if I tried these kinds of hacks in my electronics.
    BabyBlues likes this.
  13. AntimonyER

    AntimonyER AF Addict VIP Member

    So, how does everyone feel about LG being the next Nexus manufacturer?
  14. Unforgiven

    Unforgiven -.. --- - / -.. .- ... .... Moderator

    I've seen this mentioned a couple of times here. Did I miss an announcement?
  15. BabyBlues

    BabyBlues Trouble Just Finds Me! VIP Member

    I think its great that Google is seemingly giving all the makers a shot at a Nexus. I briefly got to use my Uncle's LG something or other running Android and found it to be perfectly acceptable as far as how it ran so I'd imagine LG having a Nexus could only be an improvement...unless Verizon has their hand in it as well. Then it'll get released and treated like the red-headed stepchild.
  16. jbdan

    jbdan Well-Known Member

    BB's summed it up rather well. Glad to see as many parties involved that can be. Still won't be as nice as MY/our Nexus :p
    BabyBlues likes this.
  17. MSUgEEk

    MSUgEEk Well-Known Member

    After reading a bit more on the links, it looks like the guy took a QI stardard back and soldered the +5 and +3 V source contacts together and ran them directly to the 5V input on the pogo contacts on the Nexus. Same thing for ground...solder both together and run them to the ground contact.

    I don't see a problem arising if I take the Palm +5.5~V and applying it to the 5V pin on the Rezound phone. Seems like you would run into more problem doing what the guy on the link did running 5V and 3V supplies together into a 5V pin.
  18. MSUgEEk

    MSUgEEk Well-Known Member

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  19. Stigy

    Stigy Some say... VIP Member

    So glad Motorola is getting out there and promoting Android and all its features. Although Apple people will say how Voice Actions copied Siri, but we all know its been around forever. The directions one is amazing -- we're in Maps and navigating before the iPhone even lists directions and then makes you decide on a route.

    Motorola pits Voice Actions against Siri, claims to take the title belt (video) -- Engadget

    Bumped for ya.
  20. BabyBlues

    BabyBlues Trouble Just Finds Me! VIP Member

  21. nkk

    nkk Well-Known Member

    Sounds good. All I was saying is that if there is some filtering/stepping down going on it the phone, if the phone is expecting 5V and 3V and gets only 5V with a dead 3V pin, it may not like it and the down stepping may give you less than 5V or it may not work. Either way, it is most definitely worth a try. Do post your results, as this would be important in making the now dirt cheap touchstones work with all of the other Qi devices.

    Good luck.

  22. MSUgEEk

    MSUgEEk Well-Known Member

    Found this in the XDA archive for the Thunderbolt:

    "Mainly need to do checks on the connection points for the back cover to see which connections are positive and which are negative.

    If you can, take a reading with a multimeter with the case back on and connected (as best as you can do it since the multimeter wires will have to go under the case).

    Also try another reading right after taking the case perhaps as well.

    If that isn't enough details, just let me know.


    I may not need you to do it after all. The multimeter I used was busted I think. I tried a different one and the bottom right one is + and the top left one is - and the other 2 are not used. I'll report back when I get it set up. I need some wire from the store today.

    Appreciate the offer to test though.


    I tested attaching wires to the gold prongs under the case and it showed as "charging (inductive)" when hooked up to the hp touchstone charger. I don't think it's possible to really hold them in place for a permanent solution without soldering though. They're just too tiny."

    It appears the Thunderbolt had a 4-pin arrangement where the bottom right was +5V and the top left was GND. Still doesn't explain the 5-pin arrangement on the Rezound. Really wish someone had the inductive back and a charging base that would test them with a multimeter for me.

    Same basic thing here with the D-INC 2
  23. Unforgiven

    Unforgiven -.. --- - / -.. .- ... .... Moderator

  24. nkk

    nkk Well-Known Member

    The only thing I can think of is to go to the Rezound forum either here or XDA or wherever and make an open plea. I am sure someone can do it.

    on a different note, I quickly glanced over the Qi spec sheet and I saw nothing in the specs nor in the example reference designs that would require anything more than 2 pins (V+ and gnd). So...I am at a loss.

  25. MSUgEEk

    MSUgEEk Well-Known Member

    I've had a post on XDA for a couple of days now about this and have gotten nothing. Thought being a developer forum someone would know or have the tools and the charging back to find out. May venture over to the Rezound forum here to see.

    I haven't found anything regarding the Qi specs that would require anything other than a + and - either. So much for being a "standard" :rolleyes:

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