geohsia
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2010-03-20
, 23:23
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Posts: 515 |
Thanked: 259 times |
Joined on Jan 2010
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#641
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2010-03-21
, 01:05
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Posts: 243 |
Thanked: 172 times |
Joined on Sep 2007
@ silicon valley
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#642
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2010-03-21
, 04:12
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Posts: 2,222 |
Thanked: 12,651 times |
Joined on Mar 2010
@ SOL 3
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#643
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Having not been able to see the schematic before posting that, I thought perhaps it showed the twl4030 as the phy. That's not the case.
So the twl4030 (cribbing from the tps65950 datasheet) can drive vbus using an integrated charge pump. In order to drive vbus, cp.in needs to be connected to vbat. It is. r6 (cp.gnd) is grounded which is also good. However, I don't see any indication of the CP flying capacitor being present. According to wikipedia, the source of all knowledge, a charge pump uses a capacitor to operate. AFAIK that would not be integrated with the twl4030, so the charge pump can't operate. I also don't see vbus going to any other power supply.
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So the question is, why not have the charge pump? The 4 things I can think of is a) it added too much noise b) it doesn't actually work c) it can't supply enough power to meet spec d) it's stupid and tries to charge itself off its own charge pump.
Or perhaps there is no integrated charge pump on the chip they used. As I understand charge pumps are expensive and they may have decided the demand didn't justify the additional cost.
Also, even though the ID pin is connected to the twl4030, I suspect that normally this interrupt needs to be signaled through the ulpi interface (I think that's what normally happens) which the twl4030 can't do.
The Following User Says Thank You to joerg_rw For This Useful Post: | ||
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2010-03-21
, 05:49
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Posts: 243 |
Thanked: 172 times |
Joined on Sep 2007
@ silicon valley
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#644
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I thought it'd be clear by my previous post that I've checked these details. It's not just wild guessing only when I suggest to try and patch kernel driver to set the correct bits in GAIA registers. AIUI there are all needed components present for the chargepump in twl4030 gaia. (see C4213,14,15).
No, the real question is why Nokia decided to have a dedicated PHY chip for USB instead of using the builtin in TWL4030 GAIA. There might have been silicon erata (bug in chip).
Also nota bene that detecting ID pin is more of an OTG feature and absolutely optional for the manually activated hostmode I suggested (exactly like it's usually done on N810 as well, as it seems nobody is able to get such a magic cable with grounded ID pin. And even if you could find such a cable, it had a micro-A plug while the receptacle of N900 is a micro-B - N810 is micro-AB)
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2010-03-21
, 05:56
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Moderator |
Posts: 7,109 |
Thanked: 8,820 times |
Joined on Oct 2007
@ Vancouver, BC, Canada
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#645
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Thanks for the idea but but I shoot with a DSLR and given the investment can't move systems just to send photos. I'm hoping the techno-gurus here are able to provide a more elegant solution.
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2010-03-21
, 17:28
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Posts: 2,222 |
Thanked: 12,651 times |
Joined on Mar 2010
@ SOL 3
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#646
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The beagleboard uses the tps65950 USB PHY. I thought the isp170x was used because it supported the battery charging specification and the twl4030 doesn't.
I have such an adapter. http://www.electronicproductonline.c...oducts_id=2043 http://www.electronicproductonline.c...oducts_id=2004
It works just fine.
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2010-03-21
, 18:41
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Posts: 306 |
Thanked: 566 times |
Joined on Jan 2010
@ Romania
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#647
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The Following 2 Users Say Thank You to blue_led For This Useful Post: | ||
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2010-03-22
, 01:28
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Posts: 2,222 |
Thanked: 12,651 times |
Joined on Mar 2010
@ SOL 3
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#648
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hey, guys, we are talking too much about charge pump !
We don't neet it, bellow i'll explain why !
The Following 4 Users Say Thank You to joerg_rw For This Useful Post: | ||
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2010-03-22
, 01:49
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Posts: 362 |
Thanked: 143 times |
Joined on Mar 2008
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#649
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Thanks for the idea but but I shoot with a DSLR and given the investment can't move systems just to send photos. I'm hoping the techno-gurus here are able to provide a more elegant solution.
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2010-03-22
, 02:00
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Posts: 362 |
Thanked: 143 times |
Joined on Mar 2008
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#650
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Tags |
awesomeness in the works, boulevard of broken deals, host, i am the dealbreaker, inspector gadget lies, mobidapter is a scam, nokia fanbois, otg, over 9000, usb, usbcontrol |
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