14.2.2.1 State Control

The Extended Operating Mode include RX_AACK and TX_ARET modes and are controlled by writing respective command to register TRX_CMD bits in the TRX_STATE register (TRX_STATE.TRX_CMD). Receive with Auto matic Acknowledgement state RX_AACK_ON and Transmit with Automatic Frame Retransmission and CSMA-CA Retry state TX_ARET_ON can be entered either from TRX_OFF or PLL_ON state as illustrated in Figure 14-26. The completion of each change state command shall always be confirmed by reading the TRX_STATUS bits in the TRX_STATUS register (TRX_STATUS.TRX_STATUS).

RX_AACK - Receive with Automatic Acknowledgement

A state transition to RX_AACK_ON from PLL_ON or TRX_OFF is initiated by writing the RX_AACK_ON command to the TRX_CMD bits in the TRX_STATE register (TRX_STATE.TRX_CMD). On success, reading the TRX_STATUS bits in the TRX_STATUS register (TRX_STATUS.TRX_STATUS) returns RX_AACK_ON or BUSY_RX_AACK. The latter one is returned when a frame is being received.

The RX_AACK Extended Operating Mode is terminated by writing command PLL_ON to the register bits TRX_CMD. If the AT86RF212B is within a frame receive or acknowledgment procedure (BUSY_RX_AACK), the state change is executed after finishing. Alternatively, the commands FORCE_TRX_OFF or FORCE_PLL_ON can be used to cancel the RX_AACK transaction and switch to TRX_OFF or PLL_ON state respectively.

TX_ARET - Transmit with Automatic Frame Retransmission and CSMA-CA Retry

A state transition to TX_ARET_ON from PLL_ON or TRX_OFF is initiated by writing TX_ARET_ON command to the TRX_CMD bits in the TRX_STATE register (TRX_STATE.TRX_CMD). The radio transceiver is in the TX_ARET_ON state when the TRX_STATUS bits in the TRX_STATUS register (TRX_STATUS.TRX_STATUS) return TX_ARET_ON. The TX_ARET transaction (frame transmission) is actually started by a rising edge on pin 11 (SLP_TR) or by writing the command TX_START to the TRX_STATE.TRX_CMD bits.

The TX_ARET Extended Operating Mode is terminated by writing the command PLL_ON to the TRX_STATE.TRX_CMD bits. If the AT86RF212B is in the mids of a CSMA-CA transaction, a frame transmission or an acknowledgment procedure (BUSY_TX_ARET), the state change is executed after completing of the operation. Alternatively, the command FORCE_PLL_ON can be used to instantly terminate the TX_ARET transaction and change into transceiver state PLL_ON, respectively.