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build-instructions.md

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Build Instructions

Additional components required

Hardware

  • AVR programmer (in this tutorial an Arduino is used as ISP, using another programmer should be a similar procedure)
  • soldering iron, solder
  • for programming the ATtiny: jumper cables, 10µF capacitor (just for the Arduino as ISP)
  • for the flat version: at least a hot air gun, ideally a hot air soldering station
  • optional: flux (highly recommended for the flat version)

Software

Assembly

Normal version

Get yourself all parts listed in parts-list-normal-version.txt and solder them to the pcb, starting with the SMDs. Do not solder the ATtiny directly to the pcb, use the socket instead!

Flat version

Solder all parts listed in parts-list-flat-version.txt to the main pcb. For soldering the QFN parts it is recommended to add a tiny amount of solder on the pcb pads, apply a lot of flux around them and position the parts. Heat the parts one by one with hot air until the solder starts flowing, after that the parts should align themselves. Be careful not to heat the parts to long, otherwise you can damage them!

Programming the ATtiny84A

If you have no AVR programmer, set up your Arduino as ISP and connect it to the ATtiny as shown below.

[need to add connection diagrams here]

Copy the USBKeyboard library into your Arduino libraries folder, which can normally be found under Documents/Arduino/libraries

Open the sketch rfid-password-generator-normal-version.ino respectively rfid-password-generator-flat-version.ino with the Arduino IDE and open File > Preferences. Paste http://drazzy.com/package_drazzy.com_index.json into the Additional Boards manager URLs field near the bottum and click OK. To install the ATtiny Core open Tools > Board > Boards Manager. Scroll to the bottom, select ATTinyCore by Spence Konde and click on the Install button.

Go to Tools and select Board: "ATtiny24/44/84", B.O.D.: "B.O.D. Disabled", LTO (1.6.11+ only): "Enabled", Pin Mapping: "Counterclockwise (like ATTinyCore)", Clock: "12 MHz (external)", Chip "ATtiny84", Port: "COMx" (COMx ist your Arduino port, e. g. COM3), Programmer: "Arduino as ISP". Compile and flash the sketch by clicking on the upload button.

Press Win+R, type in cmd and hit Enter to run the command prompt. Paste avrdude -c arduino -p t84 -p COMx -b 19200 -U lock:w:0xfc:m in and change COMx to your Arduino port, e. g. COM3. By running the command you lock your ATtiny, this way the flash and especially the EEPROM, where your passwords are stored, are unaccessable from the outside. The ATtiny is still reprogrammable, but the EEPROM content gets lost by doing this.

Plug the ATtiny into the socket respectively disconnect the Arduino/AVR programmer from the programming header. Add an unused RFID tag by holding it above the RFID password generator plugged into an USB port while pressing the button or after hitting Caps Lock four times, this tag will be set as your master tag. By repeating this procedure with the master tag, all saved RFID tags and their corresponding passwords will be deleted.

In the current configuration ten RFID tags (+ master tag) and therefore ten passwords with 46 colums each can be saved, it can be adjusted by changing #define passwordLength to the desired value. The number of RFID tags in relation on the password length can be calculated by 507/(password length + 4).