Cheap clones of Seeed Studio's Grove 4-digit display use the TM1637 controller IC. This chip can actually drive up to six 7-segment LED digits while also polling a 16 button keypad. This video shows how you can add two more LED digits and a 8x2 keypad to the 4-digit module, without using any more I/O pins of your microcontroller. All LED control and keypad polling are managed through the same two pins (Clk and DIO) as before.
