Introduction: Picoduino Password Keeper (PPK)

This is a password auto typer based on Picoduino. Picoduino is an Attiny85 board, similar to digispark but it has a couple of bells and whistles. For example it has a pushbutton which can be used as reset or (in our case) a user input button, and an RGB led! Also, like the digispark, it gets detected as an HID device (keyboard or mouse) which is exactly what we are going to take advantage of! It makes using complex passwords and keeping them in hand effortless.

Step 1: How It Works

This is how it works: Once you plug the PPK in a computer it flashes green and red showing that it is ready for business.

Step 2: ​Put Your Cursor on the Username Field of the Login Screen You Want Know...login...

Step 3: Pressing the Button Once Cycles Through the Available Credentials, Showing in the Username Field the Name of Each One. (the Led Flashes Red)

Step 4: When You Find the Credential You Want, Hold the Button Pressed And...pressed-to! (pun Intended) the Picoduino Auto Fills the Username and Password Fields and You 're In!(led Flashes Green)

Step 5: Prepare Your Computer

Download and install the Arduino IDE (if you haven't allready). Follow this guide to install the digispark drivers for your system.

Step 6: Optional

If you want you can follow this guide to change the bootloader. Alternative bootloaders support instant run of sketch (no 5 second delay after plugging in) and use of button as reset button.

Step 7: Prepare the Picoduino

You will have to solder a jumper in order to use the button of the Picoduino as user input. On the underside of Picoduino you will find 3 contacts. You will have to solder the contact labeled PB0 with the one right next to it (see image). Now we will be able to access the pushbutton through pin 0.

Step 8: Upload the Sketch

Using the Arduino IDE upload the sketch provided to the Picoduino. you will also need the Onebutton library. If you don't know how to install a library check here.

The Onebutton library is missing a line in order for the TAB command to work. You have to go to:


and in the file DigiKeyboard.h add

#define KEY_TAB     43

anywhere between the similar lines (see image).

Step 9: Summing Up

Would love to hear ideas on how to improve the Picoduino password keeper (PPK) in terms of security or generally in any way that it can be improved.

You can build the project with a digispark too but I find that the Picoduino is more compact, it doesn't need any extra components and dare I say it's cuter!

You can get your Picoduino at



The Picoduino Password Keeper offers no digital security, only physical. Use at your own risk.

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