the Serial println show that the transmission is failed, it can't send the data "Hello World" to the Receiver
so in the serial monitor the message shown is
failed
failed
failed
i use delay to make it send once after 1000ms
but for the details i think it is not failed at all but, i make a mistake about how to get notification when the data sent or failed, when i try the conde again this is what happen
when i used the first code, Mega as a transmitter and when i pressed the button, this happened
and when i looked out to the uno as the receiver, it happened
so i think that's work, for send simplex mode
but this happen when i press the button on my Mega and see the serial monitor
i notice, it means that the transmission is fail
now i try to make difference for the code so we can notice if the data sent from Mega or uno
in the Mega Code, i change the string from "Hello World " to "Hello world from Mega", so when we see in the uno Serial monitor as receiver, we can know that the data is coming from arduino mega, i do it for my uno too
when i press the button on my Mega(it means that my mega is tx), i see this in the serial monitor of my Uno (it means that my uno is Rx)
and when i press the button on my uno (uno as Tx), i see this in the serial monitor of my Mega (Mega as Rx)