A small 4x5 diy keypad to get into pcb design and custom keyboards.
PCB not tested yet. There's no guarantee that it will work right now!
Front panel needed to mount 3-pin switches. No files for that provided yet.
Generally this README and the whole project is far away from being
complete.
- 4x5 keys (cherry mx compatible, hotswappable)
- compatible with variety of Adafruit ItsyBitsy boards:
- 32u4 (3.3V 8MHz Version!)
- M4
- nRF52840
- RP2040?
- M0?
- up to 2 rotary encoders (optional)
- indicator RGB led (optional)
- RGB underglow (optional)
- RGB backlight (optional)
- i2c OLED-Display (optional)
- small 'prototyping' area with access to i2c, serial + some analog Pins
- PCB
- 20 1N4148W Diods (SOD123 package)
- 20 hotswap sockets for cherry mx compatible switches
- 20 cherry mx compatible switches (both 3 and 5 pin versions should work)
- compatible ItsyBitsy controller (cf. features)
- 8 SK6812 mini HW RGB LEDs for underglow + top indicator led
- 20 SK6812 mini RGB LEDs for backlight
- 0.1μF 0805 capacitors for each RGB LED (cf. notes)
- up to 2 Alps EC11E rotary encoders
- i2c OLED display, this one should fit perfectly
- front panel
- some sort of case or an extra back panel
- screws to hold the whole thing together
- rubber feet (otherwise typing won't be much fun)
- 0.1μF capacitors are recommended according to the datasheet. There are many designs without them. I do not know whether or not they are necessary.
- A resistor on the LED data line between the controller and the first led is recommended. I forgot to add that on. Here as well many pcbs do not include them. It should work. Supposedly what could happen is that the first LED in the 'chain' gets fried every once in a while.
- A wireless version could be achieved with the nRF52840 in combination with the LiIon/LiPoly Backpack.
- I experienced some form of 'ghosting' in the upper two rows when setting columns to high and reading from row pins with internal pulldowns (diodes facing opposite way than shown in schematics). When holding 4 switches down in same row, the 5th one shows as constantly on or continuously toggling. This does not seam to appear when setting rows to low and reading from columns with internal pullups. So I guess use internal pullups for scanning the matrix.