Hacking the Zsun WiFi SD Card Reader
The goal of this project is to learn as much as possible about the Zsun WiFi card reader and run OpenWrt on it to turn it into an awesome wifi device.
UPDATE 2017-09-12 Info about LEDE and USB gadget working
UPDATE 2016-11-28 Adding some more info about the new PCB revision, thanks to Erik Dorner, who sent me his analysis a long time ago
UPDATE 2016-04-23 The new PCB is missing a jumper on the RX serial line, see serial port section
UPDATE 2016-03-16 The second PCB revision has identical software and hardware (apart from optimized minor component layout), flashing works the same
UPDATE 2016-03-12 We now know that there are at least two different PCB versions of the reader!
UPDATE 2016-02-21 github mirror at https://github.com/Emeryth/openwrt-zsun
UPDATE 2016-01-27 informatic seems to have figured out how to use the original firmware’s update function: Zsun Card Reader Firmware Update Format
All the important aspects of hardware are understood.
OpenWrt Chaos Calmer ported (but not yet thoroughly tested), can be flashed over telnet if you dare.
What can I do with it?
Use it for its intended purpose of serving files, duh
Use as a tiny and pretty good WiFi AP/client/repeater (the hardware supports multiple simultaneous wireless interfaces!)
Play around with OpenWrt
Use it as the brains of your IoT project
Buy a dozen and play around with mesh networking
Use it for distributed WiFi activism like PirateBox or OccupyWiFi, or run a minimal Tor hidden service (with addition of being easily hidden in public places)
Host Node.js on it and take your apps to your favorite coffee shop :^)
Size comparison with a single 18650 cell powerbank.
16MB SPI Flash
GL827L USB SD Card Reader
The device consists of two PCBs sandwiched together and connected via 8 pins.
WARNING There are at least 2 PCB revisions, our original research was on the “old” revision, the “new” revision appeared in early 2016. The new revision has optimized layout with some minor changes, software is identical.
The bottom PCB contains only the SD card reader chip and SD slot, it can be safely removed without affecting operation. This is only true for the old PCB revision! The new revision moved the 3.3V regulator to the PCB with the card reader.
The serial console is brought out on testpoints (see pictures). Bitrate is 115200.
Original firmware root password is “zsun1188”
The new PCB has a missing jumper that connects the serial RX testpad to the SoC. Short it or solder directly to the lower pad of the jumper to use serial. (The second missing resistor is a pull up/down, I guess)
Read more: Hacking the Zsun WiFi SD Card Reader
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