UM0934 Datasheet, PDF (98/113 Pages) STMicroelectronics – ST7570 S-FSK power line networking System-on-Chip

Extended functions
UM0934
7.3.2
Server
The ST7570 set as Server also accepts a CMD_RC_Request if the command is received
from the external host while a transmission, reception or repetition is in progress over the
powerline only; otherwise it refuses it. A positive or negative confirmation
(CMD_RC_Confirm(RC_Result)) is always generated.
If accepted, the node will start the Repeater Call mode at the beginning of the first timeslot
after the completion of the current transmission, reception or repetition.
During the Repeater Call mode, the Server listens for RC messages and may also transmit
a RC pattern.
The transmitting subtimeslot position is different according the local MAC address:
● if the node is registered (address not equal to NEW), the transmitting position of the RC
message transmitted matches the local MAC address. The parameter “TxPosition” in
the CMD_RC_Request (Section 5.3.23) has to be equal to 0000h;
● if the node is not registered (address NEW) or its local MAC address is higher, the
transmitting position of the RC message transmitted matches the parameter
“TxPosition” declared in the CMD_RC_Request (Section 5.3.23) message received.
During RC messages reception, the Server performs an estimation of signal (S_RC) and
noise (N_RC) by averaging the amplitude of signal and amplitude of noise on both channels
(f₀ and f₁):
Equation 4
⎧
⎪⎪
⎨
⎪
⎪⎩
S _RC
N _RC
=
=
S₀
N
+ S₁
2
0 ^{+ N}1
2
The RC message is considered valid only if the S_RC > N_RC and S_RC is greater than the RC
detection threshold passed in CMD_RC_Request(Section 5.3.23) or (if RC_THRESHOLD =
0) written into MIB object 000Ch (RC Threshold, Section 6.5.13).
Figure 27 shows and example of Repeater Call procedure for Server, with both received and
transmitted patterns.
Figure 27. Repeater Call for Server
NORMAL MODE
RC MOD E
NORMAL MODE
TX
CC = 3
TX
CC = 2
TX
CC = 1
TX
CC = 0
RC MODE
i‐ 2
i‐1
i
i+1
i+ 2
i+3
i+ 4
CMD _RC_Re quest()
CMD_ RC_Confirm()
RE QUEST RE FUSED
CMD_RC_Reques t()
RC pattern eventually received and
notified (S, N levels and TX position ) in
CMD _RC_Confirm()
C MD_R C_Con firm()
RC pattern transmitted in subtimeslot
expressed in CMD_RC_Request()
REQUEST ACCEPTED
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Doc ID 17389 Rev 2