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Modifying Transcend WiFi SD Card Firmware

fernjager.net

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Re: Modifying Transcend WiFi SD Card Firmware

#11

Post by jmpe »

DanBC wrote: post #8
SixSigma wrote: post #6

The commercial WiFi power harvester I remembered would be the perfect partner for a WiFi Spy. Despite the announcement that "on the CES floor, they were able to charge a BlackBerry from 30% to full in about 90 minutes, using nothing but ambient WiFi signals as a power source. " [1] The device has never been turned into a commercial product. [2] [1] http://www.ohgizmo.com/2010/01/09/ces2010-rca-airnergy-charg... [2] h…

You can make a very simple GSM signal detector using a germanium diode, an LED, and a bit of wire. Tune the wire by cutting it to the right length (a square with sides of 7.5 cm is fine) and solder the diodes in series. Hold a phone near it and send a text message to the phone. http://www.creative-science.org.uk/mobile_LED.html Of course, that's a tiny amount of power but it's still there to be harvested. Not sure wh…

Legal situation?!? You're creating a matched impedance point in space.

RF energy harvesting is a bit of a hot topic, there are a number of modules on the market atm. Just search for it on mouser or farnell to get started.

Thanks btw for that LED schematic, so simple. I'm currently tuning a harvester around a BQ25504 and super caps. I'll give it a test next week.

http://uk.mouser.com/Embedded-Solutions/Energy-Harvesting-Mo...

This one contains other energy sources as well:

http://uk.farnell.com/jsp/search/browse.jsp?N=2002+225290&Nt...

Re: Modifying Transcend WiFi SD Card Firmware

#12

Post by josteink »

zdw wrote: post #7

Does anyone know if the currently available versions of the hardware ( http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3D... ) are still compatible with these modifications? I ask because frequently identical outward appearance does not mean identical internal hardware, especially on low cost consumer devices.

That's really a good question. At these prices, I would like to know before I commit to anything.

Re: Modifying Transcend WiFi SD Card Firmware

#13

Post by kybernetikos »

fernjager wrote: post #2

Author here! It was quite a surprise to see one of my old posts on HackerNews. For those interested in what happened next: I managed to build and run sqlite, rsync, and dropbear SSH on the SD card using buildroot: http://buildroot.uclibc.org/ I quickly moved onto other interests as I couldn't work out any practical applications at the time. Feel free to reach out to if you have any ideas, or want to pick my brain on…

So one of my problems with the stock functionality is that I wanted it to automatically upload images to my samba fileserver at home, rather than some weird tablet/cloud service. Having some way of printing to my network printer would be awesome too.

I also like the idea of having a tiny, relatively cheap, long running deaddrop wifi hotspot on batteries. Any idea of how long you could run it for from a button battery?

Could you create a half decent mesh network / wifi repeaters with these taped at various locations?

I could imagine a wifi hacking linux distribution like xiaopan might be quite fun too, or something with tunnelling / vpn that can connect to a hotspot and make it safe.

If there were some way to add a few sensors to it without making it much larger / power hungry, that could be really cool, especially considering how much space you have for logging.

I'd like to see if one could be surreptitiously built into a usb cable, or wall wart, so it's powered when the usb cable is plugged in, but otherwise there's nothing obviously special about the usb cable.

Re: Modifying Transcend WiFi SD Card Firmware

#16

Post by kastnerkyle »

For anyone who is interested, there is pretty good writeup here [1] on how to do kernel builds for this card. I also have a WIP of crosscompiling for this card as part of a wifi connectable (using waypoints) automated quadcopter, though I probably won't get to do more on the copter side until the fall.

My current writeup is here [2] - I am in the process of using the 8GB Transcend cards to save a few $$. I also did not experience any weirdness with the first 8 bytes of the initramfs, so I will need to investigate that further...

[1] http://dmitry.gr/index.php?r=05.Projects&proj=15&proj=15.%20...

[2] http://nbviewer.ipython.org/urls/raw.githubusercontent.com/k...

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