UM0934 Datasheet, PDF (26/113 Pages) STMicroelectronics – ST7570 S-FSK power line networking System-on-Chip

MAC layer
UM0934
Figure 10. MAC subframe structure
MAC Protocol Data Unit (M_pdu)
Frame Indicator
(FI)
Data
2 bytes
36 bytes
MAC subframes are then presented to the underlaying PHY layer for encapsulation and
transmission on the medium. According to the length of the M_sdu to be transferred (from 1
up to 242 bytes), the MAC could use from 1 up to 7 subframes (corresponding to 1 up to 7
consecutive time-slots on the medium).
During reception, the PHY layer presents all the received P_pdu frames to the MAC for
further processing. If the P_pdu frames are recognized as being part of one long MAC frame
(checking information NS), the MAC assembles them in order to rebuild the original long
frame. The long frame is then presented to upper layers through M_Data.Indication()
according to the result of the FCS and address checks.
26/113
Doc ID 17389 Rev 2