Robin2: For the future please post images as JPG or PNG files so we don't have to download them. See this Image Guide
I had no sense from your Original Post that there were 4 Arduinos involved. It just saidBut your diagram only shows a Tx sending to a single Rx.
At the moment this a typical XY problem
Please explain in simple terms what the project is all about.
- Ultra sonic sensor along with the NRF24l01 will be placed in the accident zone(Both the sides). The vehicles will have NRF24l01 incorporated which act as receivers.
- The ultrasonic sensor when senses some vehicle, the NRF24l01 transmits a message to the vehicle saying 'Accident zone'. This receiver is placed inside the vehicle. 3.If at all the NRF24l01 placed on the other side of the accident zone detects any vehicle there, it should send a message to this vehicle telling 'There's a vehicle ahead, Go slow'.
- Same is for the other side.
- I use 16*2 LCD to display these messages.