How to let the receiver know that an acknolegement packet was received by the sender?

Question

I have connected two nrf24l01+ modules using tmrh20 library. I'd like to implement the following scenario:

1. A sends a payload packet to B
2. B receives the payload packet
3. B responds with an ACK packet
4. A receives the ACK packet
5. A sends an ACK packet to B
6. B receives the ACK packet

Right now I can implement this up to step 4 by simply using this code on the sender:

bool delivered = radio.read(&message, sizeof(Message));

Is there a way to implement other steps without changing roles and writing lots of additional code? Or does the library provides some easy way of doing this?

Answer 1

You can send the ACK (which is described in step5) by putting in the payload. It might be necessaray to wrap your payload with a tiny header. This header can be used to indicate that it is data or second ACK.

#define MAX_PAYLOAD_DATA_SIZE   (10u)

typedef enum packet_type{
  DATA_PACKET, 
  ACK_PACKET,

  PACKET_MAX
}packet_type_t;

typedef struct payload{
  packet_type_t packetType;
  uint8_t len;
  uint8_t data[MAX_PAYLOAD_DATA_SIZE];
}payload_t;