1.When the key in the sending part is pressed by someone, the 1602LCD will display the value of the key.
2.The value of the key will stay on the 1602LCD until other key is pressed. The 1602LCD will refresh and display the value of the new key.
Code for your reference
Step 1: Components list
Step 2: Schematic diagram of sending part
Step 3: Schematic diagram of receiving part
Step 4: The connection of sending part
SCK--Digital pin 52 ；MOSI-- Digital pin 51
MOSI--Digital pin 50；CS——Digital pin 9 CE——Digital pin 8
Step 5: The connection of receiving part
CS——Digital pin 8