14.3.7.2 LBT Mode

The AT86RF212B supports the previously described LBT specific listening mode when operating in the Extended Operating Mode.

In particular, during Transmit with Automatic Retransmission (TX_ARET), the CSMA-CA algorithm can be replaced by the LBT listening mode when setting the CSMA_LBT_MODE bit in the XAH_CTRL_1 register (XAH_CTRL_1.CSMA_LBT_MODE). In this case, however, the MAX_CSMA_RETRIES bits in the XAH_CTRL_0 register (XAH_CTRL_0.MAX_CSMA_RETRIES) as well as the MIN_BE and MAX_BE bits in the CSMA_BE register (CSMA_BE.MIN_BE and CSMA_BE.MAX_BE) are ignored, implying that the listening mode will sustain unless a clear channel has been found or the TX_ARET transaction will be canceled. The latter can be achieved by setting the TRX_CMD bits in the TRX_STATE register (TRX_STATE.TRX_CMD) to either FORCE_PLL_ON or FORCE_TRX_OFF, the value of the TRAC_STATUS bits in the TRX_STATE register (TRAC_STATUS.TRX_STATE) is not meaningful in this case. All other aspects of TX_ARET remain unchanged.

The LBT threshold can be configured in the same way as for CCA, that is via the CCA_MODE bits in the PHY_CC_CCA register (PHY_CC_CCA.CCA_MODE) and the CCA_ED_THRES bits in the CCA_THRES register (CCA_THRES.CCA_ED_THRES), refer to Section 8.6.