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The security system application and
program offers a simple demonstration of the BASIC
Serial Interface. By adding only a few door and window
switches, a transistor, a siren, (see schematic) and a
few lines of BASIC program (see program listing) the
interface can become a multi-function security system.
Please note, however, that it is a "barebones" program.
It is left to the reader to fancy it up to their liking.
Normally closed door and window switches
can be attached to the interface "in" ports as shown in
the schematic (all unused ports should be grounded). In
this configuration with all the switches closed the "in"
port is held "low". When any switch opens the port goes
"high". The program recognizes this as an alarm
condition for the zone associated with that port. If the
program "detects" a high on "in" port number 1 it will
delay sounding the alarm for a user defined length of
time. This is done to allow the owner time to enter the
secured area and reset the alarm before the siren is
activated. If a "high" condition is detected on any of
the other ports, 2 to 7, an alarm will be sounded
immediately.
The alarm is sounded by bringing "out"
port number 1 high. Connected to "out" port 1 is a NPN
transistor which switches a 12 volt supply to a security
siren or bell (figure 3) . The alarm remains on until
the system is reset or it reaches it's time out period.
In order for the BSI to transmit the
status of it's "in" ports Data Strobe (pin. 23 of IC1)
must be toggled. This toggling of the Data Strobe is
done by program control. In this application Data Strobe
is connected to "out" port 8 by a jumper. In order to
trigger a transmission of the port conditions the
program turns "out" port8 "on" then "off". This causes
IC1 to transmit the status of it's "in" ports.
10 ' BASIC SERIAL INTERFACE
20 '
30 ' SECURITY SYSTEM DEMONSTRATION PROGRAM
40 '
50 ' setup
60 KEY OFF:CLS:CLOSE'.........................................
turn key off, clear screen, close
70 OPEN "COM1:1200,N,8,2" AS #1'
.......................all files, open the serial port
80 PRINT#1,CHR$(NUL);'.........................................as
com port #1, and transmit "0".
90 GOTO 310
100 '
110 FOR X=1 TO
8'..................................................
Subroutine to convert decimal number
120 B=C MOD 2:C=INT(C/2):R(X)=B'......................
received from the UART to binary
130 NEXT
X'.............................................................
and set array variables to represent
140
RETURN'.............................................................UART
port conditions,R(1) to R(8)
150 REM
160 IF T(HP)=1 THEN
210'.......................................Subroutine to
turn one UART port on
170 FOR X=1 TO
8'..................................................without
changing the condition of
180 IF HP=X THEN OT=OT+2^(X-1):T(X)=1'...............any
other UART port.---
190 NEXT X
200 PRINT #1,CHR$(OT);
210 RETURN
220 '
230 IF T(HP)=0 THEN
280'........................................Subroutine
to turn one UART port off
240 FOR X=1 TO
8'...................................................without
changing the condition of
250 IF HP=X THEN
OT=OT-2^(X-1):T(X)=0'................any other port.---
260 NEXT X
270 PRINT #1,CHR$(OT);
280 RETURN
290 '********************* SECURITY SYSTEM MAIN PROGRAM
*******
300 '
310 PRINT" Security System Program
320 '
330 PRINT:PRINT"Note:'OUT' port 8 of the UART (pin 5)
must be connected to Data Strobe (pin 23)before running
this program.":PRINT
340 INPUT"ENTER ALARM DELAY FOR ZONE #1 ENTRY ";DELAY
350 INPUT"ENTER ALARM TIMEOUT ";TIMEOUT
360 '
370 CLS:PRINT#1,CHR$(128);'.................................clear
screen and turn UART port 8 on
380 PRINT "Ctrl E to reset"
390 HP=8 :GOSUB 220:HP=8:GOSUB 150'................Ask
UART for 'in' port status.
400 IF LOC(1)=0 THEN
470'.......................................If
transmission not received,skip.
410 IN$=INPUT$(1,#1):C=ASC(IN$):GOSUB 100'... read
transmission and convert to
420 FOR X=1 TO
8'......................................................binary,assign
each bit to array R(X)
430 LOCATE X+9,10
440 IF R(X)=1 THEN PRINT X;" ALARM !!!!!"' Print UART
port status conditions
450 IF R(X)=0 THEN PRINT X;" ZONE SECURE"' as either
'alarm' or 'secure'
460 NEXT X
470 IF R(1)=1 THEN
TIME=TIME+'.............................If zone 1 is
high start delay time.
480 IF TIME=DELAY THEN ALARM=1'.......................if
delay time is up set alarm.
490 FOR X=2 TO 8
500 IF R(X)=1 THEN
ALARM=1'..................................if any
zone,2-8,is high,set alarm.
510 NEXT X
520 IF ALARM=1 THEN HP=1:GOSUB 150'............... if
alarm set,turn port 1 on.
530 IF ALARM=1 THEN RESETT=RESETT+1'............ if
alarm is set start timeout.
540 IF RESETT=TIMEOUT THEN GOTO 580'............ If
timeout is up then shutdown.
550 A$=INKEY$:IF A$="" THEN 570'........................
Check to see if Ctrl E was entered,
560 IF ASC(A$)=5 THEN
50'...................................... if it was then
reset program.
570 GOTO 390
580 PRINT#1,CHR$(NUL);'.......................................Turn
alarm off
590 PRINT:PRINT"SYSTEM SHUTDOWN AT "TIME$,DATE$ ' print
shutdown
600 END
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