UM0934 datasheet(97/113 Pages) STMICROELECTRONICS

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UM0934

Extended functions

Doc ID 17389 Rev 2

97/113

7.3

Repeater call

The Repeater Call (RC) is a special service supported by the ST7570 at MAC layer, with

specific short messages (RC messages).

During the Repeater Call mode, the physical layer does not send or receive the frames over

powerline in the usual form. In fact, the physical time-slot (Section 3.3) is split down into 21

sub-timeslots (SubTslot) with a duration equivalent to 2 bytes. Since the Pause/Alarm time

is not used by the RepeaterCall function, the alarms remain active during this period.

During each sub-timeslot of the RepeaterCall mode, a node can either receive or send a 2-

byte fixed pattern (2EC5h), with a behavior in accordance with its configuration (Client or

Server).

7.3.1

Client

The ST7570 will accept a CMD_RC_Request if this command is received while a

transmission or reception on powerline is in progress only, and refused otherwise. If

accepted, the node will start the Repeater Call mode at the beginning of the first timeslot

after the current transmission or reception completion.

The Client leaves the Repeater Call mode and goes back to the normal mode after one

timeslot.

A confirmation and an exit code (CMD_RC_Confirm(RC_Result)) are always generated to

the host.

The ST7570 configures as a Client will transmit the RC message at position 0 (first sub-

timeslot), whatever is the value of parameter “TxPosition” in the CMD_RC_Request.

The Figure 26 shows an example with a Client sending a MAC frame with IC=CC=3 and a

M_sdu of 26 bytes.

Figure 26.

Repeater call for client

UM0934 Datasheet(PDF) 97 Page - STMicroelectronics