One major advantage of the TM1638 module is that it calls for just three I/Os (Data, Clock, Strobe) of the concerned microcontroller for the full play. As mentioned, the interface pins are data, clock, and strobe. The strobe (STB) and clock (CLK) pins are only outputs while the data (DIO) pin works for both input and output. The strobe pin is required when sending data to the module.
While sending data you must set the clock pin to ‘low’, then you set the data pin, and then set the clock pin back to ‘high’ to commit the bit value. Perhaps you’re already familiar with this method as it is a common way of sending data with shift registers. And hence it’s possible to use the standard ‘shiftOut’ function to send 8 bits of data with just a single line of code.