Keyboard for Arduino, RPI, STM32, ESP8266, ESP32 i2c peripheral

thingiverse

Arduino 39 keys keyboard with i2c interface for STM32, AVR or any other microcontroller with 3.3 or 5V supply. Size 4x10 cm using 6x6 mm tactile switches. The controller (Arduino Mini 3.3V 8Mhz) is dedicated to this application, and serves as i2c peripheral with interrupt to a host computer. Print the 3D STL file or prepare the K40 laser engraving, then position the 39 switches in it when soldering in a perfboard. Solder on 7 vertical and 6 horizontal bus wires and connect it to 7 inputs (pullup) and 6 outputs (1k resistor) to any microcontroller. The 6x7 matrix results in 42 scan codes, from which we use 39, so 3 keys could be added, e.g. comma, minus sign, point simply by extending the arrays. Pressing a key will generate an interrupt pulse, polling works as well. The master can control the backlight. The second - commented - part of the .ino program shows an example how the master can handle the interrupt, the enter and delete keys, and the PWM. The LYZ file has engrave and cut layers. In the STL file case there is place for a tumbwheel switch, connected to 3 free inputs on the microcontroller. Application : https://www.thingiverse.com/thing:4747833 (without i2c) This object was made in Tinkercad. Edit it online https://www.tinkercad.com/things/7fpYyQpQNwc