14.4.4.2 User accessible Frame Content

The AT86RF212B supports an IEEE 802.15.4 compliant frame format as shown in the figure below.

A frame comprises two sections, the radio transceiver internally generated SHR field and the user accessible part stored in the Frame Buffer. The SHR contains the preamble and the SFD field. The variable frame section contains the PHR and the PSDU including the FCS, see Section 8.3.

To access the data, follow the procedures described in Frame Check Sequence (FCS).

The frame length information (PHR field) and the PSDU are stored in the Frame Buffer. During frame reception, the link quality indicator (LQI) value, the energy detection (ED) value, and the status information (RX_STATUS) of a received frame are additionally stored. The radio transceiver appends these values to the frame data during Frame Buffer read access.

If the SRAM read access is used to read an RX frame, the frame length field (PHR) can be accessed at address zero. The SHR (except the SFD value used to generate the SHR) cannot be read by the microcontroller.

For frame transmission, the PHR and the PSDU needs to be stored in the Frame Buffer. The maximum Frame Buffer size supported by the radio transceiver is 128 bytes. If the TX_AUTO_CRC_ON bit in the TRX_CTRL_1 register (TRX_CTRL_1.TX_AUTO_CRC_ON) is set , the FCS field of the PSDU is replaced by the automatically calculated FCS during frame transmission.

To manipulate individual bytes of the Frame Buffer a SRAM write access can be used instead.

For non IEEE 802.15.4 compliant frames, the minimum frame length supported by the radio transceiver is one byte (Frame Length Field + one byte of data).