UM0934 datasheet(109/113 Pages) STMICROELECTRONICS

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UM0934

MAC mode communication example

Doc ID 17389 Rev 2

109/113

As station1 has already achieved the time-slot synchronization, it does not generate any

CMD_SynchroIndication() notification.

10.4.1

Station2 (Server)

Status message

Before sending the data request, the external host must set the T_REQ signal at low level

and wait for the status message from the ST7570 modem.

The status message can be used by the external host to quickly retrieve useful information

about the status of the modem. A typical status message is as follows:

●

Byte 0: 3Fh (“?” ASCII code)

●

Byte 1: 22h

⇒ MAC server mode, not NEW, synchronized, not busy

●

Byte 2: E4h

⇒ TS_COUNTER=7, alarm not received in the previous time-slot, PLL not

ZC_FAIL, device out of hardware reset/boot, FW release = 1

●

Byte 3: 80h

⇒ Phase = 4 (180°), Delta Credit = 0, No repeater

CMD_DataRequest

The local frame encapsulating the CMD_DataRequest():

The fields are filled in the same way as the data request from Client to Server

(Section 10.3.1), with the only exception on the address sub-field:

●

SA: 001h, DA: C00h

⇒ Address = C0.00.01h

CMD_DataConfirm

As soon as the transmission over the power line is complete, station2 generates locally a

CMD_DataConfirm() as follows

The data value equal to FFh (LP_OK, Section 5.3.13) notifies that the transmission

completed successfully.

“? ”

ASCII

byte

nd byte 3rd byte

3Fh 22h

E4h

80h

STX Length

Command

Code

DATA

CHK

02h 22h

51h

D4. 01h

Pad

00h

Addres s

00.1C.0 0h

Credit

00h

00.01 .02.03.04.05.06.07.08.09.0A.0B.0C.0D.0E.0F.10.11.12.13.14.15.16.17.18.19h

M_SDU

STX

Length

Command

Co de

DATA

CHK

02h 04h

52h

55.01h

FFh

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