Close
0%
0%

Keypad

49-key mini keypad

alanrcamalan_r_cam
Following
Liked Like project

Just one more thing

To make the experience fit your profile, pick a username and tell us what interests you.

Pick an awesome username
hackaday.io/
Your profile's URL: hackaday.io/username. Max 25 alphanumeric characters.
Pick a few interests
Projects that share your interests
People that share your interests

We found and based on your interests.

Choose more interests.

OK, I'm done! Skip
Similar projects worth following
5 comments
118 followers
View Gallery
This is/was the start of a clamshell - style calculator. A 49-key keypad, about 10cm x 6cm. Thanks to the Calculator origins, the artwork has suggested calculator functions for the keys.
The connector is PMOD-compatible, with and extra pin used to send interrupts back to the microcontroller. Schematics and PCB are in KICAD files at the Github.

There are other mini keyboards around: fully functional, bluetooth connection, and cost less than what I'm charged for SMD switches [let alone diodes, board, controller chip, case, keycaps etc]. But maybe the design can be used as a stating point for YOUR design...
  • 1 × TCA8418 Evaluation, Demonstration Kits, Boards and Modules / Evaluation Kits, Boards and ModulesKeyboard Encoder
  • 49 × 1N4148 SMD Diode Discrete Semiconductors / Diodes and Rectifiers
  • 49 × EVQ-PQHB55 SMD Switch Switches and Relays / Switches
  • 2 × 10K Resistor SMD Resistor
  • 2 × 4K7 Resistor SMD Resistor

View all 7 components

Enjoy this project?

Share

Discussions

Jan Szumiec wrote 10/04/2016 at 20:26 • point

Hey, I'm building something simliar. What do you need the diodes for in this design?

  Are you sure? yes | no

alan_r_cam wrote 10/05/2016 at 09:50 • point

n-key rollover is a problem when you press multiple keys (control-alt-delete). Theres some great write ups in the Reddit groups on mechanical keyboards. The fix is the diodes.

If you never expect to be pressing multiple buttons at once, you could leave them out. Your choice

  Are you sure? yes | no

Jan Szumiec wrote 10/05/2016 at 10:02 • point

Thanks, this is very useful info.

  Are you sure? yes | no

alan_r_cam wrote 03/12/2014 at 02:52 • point
My original plan was to mate this with a 4.3" LCD, a battery, and an ARM microcontroller. However, my first batch of PCB's have already cost more than the eBay price of a mini Bluetooth wireless keypad. This has severely impacted my desire to continue with the design.
Common sense tells me I should just use a existing keypad, coupled with an iPhone or Android. What do you think?

  Are you sure? yes | no

Rocko wrote 03/29/2021 at 23:12 • point

Your original plan is way cooler.  It may cost more but, you will get more out of it I think.  Also, one of anything you design will always cost more than one of anything on eBay.

  Are you sure? yes | no

Does this project spark your interest?

Become a member to follow this project and never miss any updates

Going up?

About Us Contact Hackaday.io Give Feedback Terms of Use Privacy Policy Hackaday API

© 2025 Hackaday

Yes, delete it Cancel

Report project as inappropriate

You are about to report the project "Keypad", please tell us the reason.

Send message

Your application has been submitted.

Remove Member

Are you sure you want to remove yourself as a member for this project?

Project owner will be notified upon removal.