Looking for USB host pads

[peterson]

I am looking for the (internal) USB host connection on a Kindle Paperwhite 2 (I believe the PW3 would be identical). This supposedly should be near the SIM card / 3G module connector. On the KT at least there seems to be two pads (see https://www.mobileread.com/forums/sho...&postcount=159 and https://www.mobileread.com/forums/sho...&postcount=166)

On the PW2, the board layout is different. I have found a good connection for power, but I have no clue which of the pads could be the two data lines for USB.

I've annoted the picture from https://www.mobileread.com/forums/sho...d.php?t=229223 with what I know so far. The cyan dots mark pads that are GND.

Does anybody know where (or if) DATA+ and DATA- are available on an open Kindle Paperwhite 2 (rev 11), or could make an educated guess based on the image? Alternatively I would also appreciate any hints on how to figure this out myself.

TIA

[knc1]

try 36 and 38 first.
http://www.allpinouts.org/index.php/...ress_Mini_Card

You don't mention what test equipment you have available.
Its hard to make "howto" suggestions without that information.

[peterson]

Originally Posted by knc1

try 36 and 38 first.
http://www.allpinouts.org/index.php/...ress_Mini_Card

Are you sure this is PCI express mini? Because as you can see from the image there are only 50 pins, but it should be 52. And at least pin 21, 27 and 50 should, according to the website, be GND but they aren't on the PW2. And 48 should be 1.5 V but I'm not measuring it. At least assuming that pins 1-50 are equivalent and they just removed pins 51/52.

You don't mention what test equipment you have available.
Its hard to make "howto" suggestions without that information.

I have a multimeter and a semi-decent soldering station at home. At work I could ask a colleague to take a look with an oscilloscope, and I have access to better soldering stations (both with a heated element and with hot air, dunno what the professional english terms are).

[knc1]

Originally Posted by peterson

- - - -

I have a multimeter and a semi-decent soldering station at home. At work I could ask a colleague to take a look with an oscilloscope, and I have access to better soldering stations (both with a heated element and with hot air, dunno what the professional english terms are).

An oscilloscope would be the first choice.
IIRC, USB is 8-in-10 differential (a web-search would give the answer).

I am not sure how you would put a signal on that pair, after the kernel discovers there isn't anything on them.

I would expect the USB leads to go directly to the SoC, the pins of which you can't reach physically.

Also, I don't recall if the USB I/O goes through the cross-bar switch.
You should be able to find out that in the iMX6 reference manual.
https://www.mobileread.com/forums/sho...d.php?t=249979
(last attachment to post #2)

Also, there may be a built-in USB hub in the SoC. See above.

In any case, the USB driver (hardware) will have a fixed i/o address, you should be able to diddle that directly (once you know what/where) in the /proc image of memory.

Other than those hints, looking at the Amazon/Freescale USB kernel driver is probably the only real source of information.
I.E: It has to run discovery somehow.

[peterson]

We took a close look and multiple people (more experienced than I in that regards) are sure that this is not PCI express mini. I decided not to pursue this path further (though would still appreciate if anybody already knows and could share this knowledge). I would need significant time myself and from my colleagues assisting me, which I don't have and don't want to ask of them.

I will now approach my goal differently. What I want to achieve is wireless page flipping. I still have the serial port available, plus WiFi. My choice would be to use a bluetooth2serial device and some "camera shutter remote" (search Amazon with these words and you see what I mean). This sounds like the most energy efficient version (ideally using BLE), but I haven't found a good solution yet (the nrf51822 seems like a good choice, but then I'd need to have both receiver and sender with it, and it seems there is no easily available source code yet). For now, I got hold of an ESP8266 and will build a remote that sends keypresses over wifi (already have a small script running on my Kindle PW2 that listens on a UDP port and depending on the received packet flips the page for- or backward).

[knc1]

Zigbee?

[peterson]

Maybe. For now I will build a first version using WiFi. I got the ESP2866 running, tomorrow I'll get the parts to have it powered by battery. Software is rudimentary done, I will post a tutorial once I have something stable. Biggest issue left is actually how to package everything together to actually hold it :-)

Depending on how bad this affects battery (both in the remote and the Kindle) I may attempt a second version using BLE or maybe Zigbee.

[knc1]

I suggested Zigbee because of its low power consumption.
Bluetooth is notoriously a power hog.

[peterson]

Originally Posted by knc1

I suggested Zigbee because of its low power consumption.
Bluetooth is notoriously a power hog.

I would focus on Bluetooth Low Energy, which should be comparable if not better according to http://research.microsoft.com/pubs/1...onsumption.pdf. For the use case at hand, the differences between ZigBee and BLE should not be that relevant. For BLE, you get the very popular (and cheap) nrf51822 with everything baked in. There are several modules using that for easy integration, too, so this looks very promising for this kind of application. However programming it seems to be more involved, hence my focus on the ESP8266 for now (which you can easily flash with NodeMCU and then simply program it in LUA). But maybe I just haven't found the right documentation or the right example software.