Application

	AN517
	Product: Domino, Serial Plix
Transmitting and Receiving Data over AC Power Lines.	Date: 6/15/99
Introduction: Transmitting data over power lines using Serial Plix can be very simple. The following application note demonstrates how to accomplish this by using any two micro-controllers with the two Serial Plix chips.
Background: The Serial Plix is an 18-pin CMOS chip, which provides an intelligent communication interface between a serial port and X-10 AC power-line control modules. Using the Serial Plix and a TW523 to transmit and receive data, it is very easy to have a micro-controller perform a specific task remotely.
How it works: This application note demonstrates a generic micro-controller transmitting a series of commands to the Serial Plix and having it transmit M14 followed by M15, when a door opens. The code sequence of M14 and M15 is user defined. The Domino is used to tell the Serial Plix when to look for data on the power lines and if the Domino receives M14 followed by M15 from the Serial Plix, the Domino then sets an output bit high to sound a piezo buzzer. The following flow chart and schematic show the necessary steps and connections required for any micro-controller to monitor the door. The following schematic is the connections needed for the Domino 2 to operate as the receiver.
Program Listing: 10 REM* This program demonstrates receiving data 20 REM* over the power lines. 30 MTOP=12288 40 REM * Allocate memory for one 4-byte string. 50 STRING 6,4 60 REM * Set PB4 as an output. 70 PUSH 2033H,EFH 80 CALL 0F128H 90 POP C 100 REM * Coprocessor error checking 110 IF C<=255 THEN GOTO 160 120 REM * Setting P1.7 and P1.6 high masking the rest of the port. 130 PORT1=PORT1 .OR. 0C0H 140 GOTO 70 150 REM * Set PB4 low 160 PUSH 205CH,0 170 CALL 0F128H 180 POP C 190 REM * Coprocessor error checking. 200 IF C<=255 THEN GOTO 240 210 PORT1=PORT1 .OR. 0C0H 220 GOTO 160 230 REM * Transmit to the Serial Plix. 240 ?"$DINA9950", 250 REM * Receive from the Serial Plix. 260 INPUT $(0) 270 REM * Taking the House and Unit code from the Serial Plix 280 REM * and storing them into variables A, B, and C. 290 REM * To figure out where the variables are in memory 300 REM * you subtract the total bytes expressed in the 310 REM * string from MTOP. In this situation it is 320 REM * 12288-6=12282. Since we don't need to store the 330 REM * lead in character(!) we start at 12283. 340 A=XBY(12283) 350 B=XBY(12284) 360 C=XBY(12285) 370 IF (A<>77.OR.B<>49.OR.C<>52) THEN GOTO 240 380 REM * Transmit to the Serial Plix. 390 ?"$DINA9950", 400 REM * Receive from the Serial Plix. 410 INPUT $(0) 420 A=XBY(12283) 430 B=XBY(12284) 440 C=XBY(12285) 450 IF (A<>77.OR.B<>49.OR.C<>53) THEN GOTO 390 460 REM * Set PB4 high. 470 PUSH 205CH,1 480 CALL 0F128H 490 POP C 500 REM * Coprocessor error checking 510 IF C<=255 THEN GOTO 550 520 PORT1=PORT1 .OR. 0C0H 530 GOTO 470 540 REM * Delay the program for 1 second. 550 TIME=0 : CLOCK1 560 IF TIME<1 THEN GOTO 560 570 CLOCK0 580 GOTO 160