explanations on the prints

README.md

@@ -77,7 +77,19 @@ values = d.read_inputs()
 print(values) # prints {2: 1, 6: 0, 15: 1}
 ```
 
-## Error handling
+## Prints handling
+
+By default, print statements from the device are relayed and displayed as:
+
+```txt
+MPY_PRINT@COM1:HELLO WORLD
+```
+
+These messages can be suppressed by passing `show_prints=False` when instantiating the device.
+
+For more complex message exchange, it's best to pass a string to the host computer with a `return` statement.
+
+## Exceptions handling
 
 Exceptions on the MicroPython side are turned into Python exceptions, which can help you debug the embedded code. You can catch them and react accordingly: