When the AES CCM is encrypting a packet at the same time as the radio is transmitting it, the radio must read the encrypted packet from the same memory location as the AES CCM is writing to.
The OUT.PTR pointer in the AES CCM must therefore point to the same memory location as the PACKETPTR pointer in the radio, see Example configuration of encryption during radio transmission.
The START task must be triggered by RADIO READY event to ensure that the payload is encrypted in time for radio transmission. This is illustrated in the following figure, using a PPI connection between RADIO.EVENTS_READY and CCM.TASKS_START.