Zeroplus Arduino starter kit with Logic Analyzer Manual page 116

25. Now press again the button connected to the pin 2 and press
the button Data and Send. The color changed again.
26. Once again press the button connected to the pin 2 and the
buttons Send. You can see another 4 digits number on the
serial monitor, different from the previous one. As shown
below.
27. The same number will be printed if you push again the button
Send. And if you press the button connected to the pin 2
then the buttons Data and Send, then the button connected
to pin 2 again and the button Send, it will print the
first number. Thus, for each color of the LEDs a different
number is printed. And this number is sent from the I2C
device to the serial monitor. So we can assume that this
button connected to the pin 2 is a Read/Write button. When
in position Read it prints the current state of the device