The M5Stack CardKB v1.1 is a card-size '50 key' QWERTY keyboard which adopts an ATMega8A as the MCU. It features an I2C communication port and one 'RGB-LED' indicator.
Consider that you want to make some cool stuff that requires keyboard typing and interaction, but the M5 core by itself only has a few buttons, what can you do? Well, you can use a CardKB!
CardKB also can achieve button combinations (Sym+Key, Shift+Key, Fn+Key) and output richer key values. This unit communicates with M5Core units through GROVE A port (I2C interface). The default Address is 0x5F.
Instructions
Single button pressed: Keyboard will output the first key value (the letter button will output in a lowercase form). E.g if "Q" was pressed, the keyboard will output "q" (lowercased).
Sym+key: Keyboard will output the second key value. E.g if "Sym" was pressed and then "Q" was pressed, the keyboard will output "{". If "Sym" was double pressed, then the keyboard will lock this function, all key pressed will output it's second key value.
Shift+key: If a letter button was pressed, it'll output upper case form. E.g if "Shift" was pressed and then "Q" was pressed, the keyboard will output "Q". If "Shift" was double pressed, then the keyboard will lock this function, all letter keys pressed will output its upper case form.
Fn+key (custom function key combination): Keyboard will output the third key value. You can customize what function the key presses correspond to.