SWCU191 February 2022 CC1311P3 , CC1311R3 , CC2651P3 , CC2651R3 , CC2651R3SIPA
After a packet is received, the radio CPU initiates transmission of an acknowledgment frame, given that all of the following conditions are satisfied:
The transmit time of the ACK packet is timed by the radio CPU, depending on frameFiltOpt.slottedAckEn. If this bit is 0, the ACK packet is transmitted 192 µs after the end of the received packet. Otherwise, slotted ACK is used. Assume that the received packet started on a backoff-slot boundary. The ACK frame then starts a whole number of backoff periods later than the start of the received frame, at the first backoff boundary following at least one TurnaroundTime-symbol period after the end of the received frame.
The contents of the automatically transmitted ACK frame are as follows:
After the ACK frame is transmitted, a TX_ACK interrupt is raised. The radio CPU then enables the receiver again.