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TAXI
PHONE
Page 2
Mouseover to stop
MODIFYING THE PROGRAM
The program can be developed in an F84 chip using an 8-Pin to 18-Pin adapter
as shown below. The set-up instructions we have used in the program apply
equally to the '508A and F84. The only difference is you must assemble the
program in MPASM for the F84 during experimenting and when you are ready to
put it into a '508A, the program must be assembled for a PIC12c508A. This
will produce two completely different .hex files.
There are a number of areas
where the program can be modified to suit different requirements. The first
is the dialling speed. The program sends out the DTMF tones at approx 5
tones per second. Many phone lines will accept this rate (and higher rates)
but if you are experiencing problems with your carrier, the rate of
transmission can be reduced. The tones can be produced for a longer period
of time (at DTMF1 the number of loops can be increased to 0F0h) and the
delay between tones can be increased (at Dial2, add another one or two CALL
Del1 instructions).
The delay before beginning to send the tones can be increased, depending on
how long it takes for your phone system to pick up a line. Don't
increase it too much as surprise is the essence of this alarm.
If you have a number of these alarms at different locations, the Hee Haw
sound can be altered for each location. Or the program can be altered to
deliver a 4 digit code and a receiver at a central location can identify the
particular alarm.
CONNECTING THE PROJECT TO A PHONE LINE
The requirements for connection to a Public Telephone system vary from country
to country and you must find out the full
details for your own country. This project must not be connected without an authorisation number.
To get an authorisation number, the design has to go through approval stages
and this could cost $2,000 - $5,000 or more. Compliance is extremely strict, with the requirement that every component has to be "authorised for
connection to the line" and at least 5,000v isolation between components and user.
After approval has been granted, the authorisation number has to attached to the product.
The only way to work on this project is to get an "experimental licence" and place the project behind a "telephone line isolating device."
These are available from Altronic Imports in Perth, WA. in Australia.
When we refer to "connecting to the line" in this project, we mean connecting to an experimental line made up of
27v from 9v batteries, a 1k relay in
series with one line and terminating with a 4-pin modular telephone plug for
connection into the project, as shown below. A switch on the project
allows it to be turned off (bypass mode). Use the ON mode
for testing.
BEFORE BURNING A CHIP
Before burning a chip, Table1 must be increased to at least 100 RETLW 0FFh to allow for
reprogramming of phone numbers. For example, a 10 digit number, with RETLW
0E, takes 11 RETLW 0FFh's.
Next, insert the digits of the phone number you wish to call. End with RETLW 0E.
The RETLW values for the digits co-relate exactly except for 0 = 0A as 0 represents ten pulses and ten in hex is 0A!
Note: there is no: RETLW 00h!!
1 = RETLW 01h
2 = RETLW 02h
3 = RETLW 03h
4 = RETLW 04h
5 = RETLW 05h
6 = RETLW 06h
7 = RETLW 07h
8 = RETLW 08h
9 = RETLW 09h
0 = RETLW 0Ah
E = RETLW 0Eh - End of phone number
Do not code-protect the chip as the phone number must be able to be removed when re-burning. This is done by burning down the
old digits to 00 00h and the next RETLW 0FFh locations are converted to RETLW 01h etc, for dialing.
When burning a PIC12C508A, in the Fuse Edit section of the PIP-02 programmer,
place a dot (o) beside XT and a cross (X) beside Watchdog Timer On. The MCLR
feature is internal and cannot be altered. Make sure CP:
OFF The ID and CSum is not important.
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;TAXI PHONE for
12c508A CHIP
Note: This program does not dial a recognised telephone number.
Insert the phone number to be dialled at Table1.
;'508A Files used
in this program
;07h
;08h
;09h
;0Ah
;0Bh
;0Ch
;0Dh
;0Eh loop file
;0Fh
;10h jump file for tables
;11h
;12h Count file
;13h Carrier DTMF
;14h Low tone
;15h decrementable low tone
;16h High tone
;17h decrementable high tone
;18h
;19h
;1Ah delay routines
;1Bh delay routines
;1Ch delay routines
;1Dh
;1Eh
;1Fh
SetUp MOVLW 08 ;Put 0000 1000 into W
TRIS 06
;Make GP3 input
CLRF 06
;Clear port 6 of junk
BSF 01h,0
;Prescaler bit0
BSF 01h,1
;Prescaler bit1
BSF 01h,2
;Prescaler bit2 = WDT x 128
BSF 01h,3
;Prescaler assigned to WDT
StartUp GOTO Main1
;Table 1 for storing phone number
Table1 ADDWF 02,1 ;File 02 = Low bits of program counter
RETLW 0Ah ;0
RETLW 01h
RETLW 01h
RETLW
02h
RETLW 03h
RETLW 02h
RETLW
09h
RETLW
02h
RETLW
05h
RETLW
05h
RETLW 0Eh
;E = End of number
RETLW 0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh
RETLW
0FFh ;etc etc etc ETC ETC
;Table2 DTMF Low tones
Table2 ADDWF 02,1 ;File 02 = low bits of program counter
NOP
RETLW 075h
;1
RETLW 075h
;2
RETLW 075h
;3
RETLW 06Bh
;4
RETLW 06Bh
;5
RETLW 06Bh
;6
RETLW 060h
;7
RETLW 060h
;8
RETLW 060h
;9
RETLW 057h
;0
;Table3 DTMF HIGH tones
Table3 ADDWF 02,1 ;File 02 = Low bits of program counter
NOP
RETLW 044h
;1
RETLW 03Dh
;2
RETLW 037h
;3
RETLW 044h
;4
RETLW 03Dh
;5
RETLW 037h
;6
RETLW 044h
;7
RETLW 03Dh
;8
RETLW 038h
;9
RETLW 03Dh
;0
;Short delay between tone approx 50mS
Del1 CLRWDT
MOVLW 50h
;loops
MOVWF 1B
;
Del1A DECFSZ 1A,1
;Will produce 256 decrements
GOTO Del1A
DECFSZ 1B,1
;decrements file 1B
GOTO Del1A
RETLW
00
;0.7sec Delay
Del2 CLRWDT
NOP
;NOP's to pad out the delay routine to
NOP
;create more than 655,000uS delay
NOP
;(approx 0.7sec delay)
NOP
NOP
NOP
NOP
DECFSZ 1A,1
;After one pass, each file will be
GOTO Del2
;256 and will produce the longest
DECFSZ 1B,1
;delay-time.
GOTO Del2
RETLW
00
;Dial1 dials the DTMF phone number
;13h = carrier file
;14h = low tone
;15h = decrementable low tone
;16h = high tone
;17h = decrementable high tone
Dial1 MOVF 10h,0
;Put 10h into W
CALL Table1
MOVWF 13h
;Put W into 13h - carrier
MOVLW 0E
;Look for E - end of number
XORWF 13h,0
;Is 13h = E?
BTFSC 03,2
GOTO Main4
MOVF 13h,0
;File 13h will be 1,2,3 ..0A
CALL Table2
;Get low-tone value
MOVWF 14h
;Put low-tone into 14h
MOVWF 15h
;Decrementable low-tone file
MOVF 13h,0
CALL Table3
MOVWF 16h
;Put high-tone into 16h
MOVWF 17h
;Decrementable high-tone file
CALL DTMF1
Dial2 CALL Del1
;Short delay before next
CALL Del1
; digit
INCF 10h,1
GOTO Dial1
DTMF1 MOVLW 0A0h
; loops of tone
MOVWF 11h
; to produce 1/10th sec
DTMF2 DECFSZ 17h,1
;Decrement high-tone file
GOTO DTMF3
MOVLW 01
;To toggle GP0
XORWF 06,1
;Toggle GP0
MOVF 16h,0
;To re-load high-tone file
MOVWF 17h
;Re-load high-tone file
DTMF3 DECFSZ 15h,1
;Decrement low-tone file
GOTO DTMF2
MOVLW 02
;To toggle GP1
XORWF 06,1
;Toggle GP1
MOVF 14h,0
;To re-load low-tone file
MOVWF 15h
;Re-load low-tone file
DECFSZ 11h,1
;Decrement loops file
GOTO DTMF2
GOTO Dial2
;Main
Main1 CALL Del2
;0.7sec delay
CALL Del2
;0.7sec delay
CLRF 10h
;Jump value for Table1
Main2 MOVF 10h,0
;Look for NOPs in Table1
CALL Table1
; so chip can be re-burnt
XORLW 00h
BTFSS 03,2
GOTO Main3
INCF 10h,1
GOTO Main2
Main3 BTFSS 06,3
;Is auto-dial Sw closed? = GP3=LOW
GOTO Main4
;Yes. Auto Sw closed = GP3 = LOW
Sw CALL Del2
;No. Wait for Sw to be pressed
BTFSC 06,3
;Is switch pressed?
GOTO Sw
;No. Loop here until Sw pressed
Main4 GOTO Dial1
;Yes.
Main5 NOP
;Loop forever after dialing
CLRWDT
;WDT will turn project on
GOTO Main5
; when power is applied
END
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The program above has been laid out with spacing and
is not suited for importing as a text file. To download the text file as Taxi-1.zip,
click HERE.
The .zip holds Taxi-ASM.asm and this is suitable for both
the PICF84 and
'508A.
No .hex file has been provided as you must add your own phone
number to the .asm file above and create your own .hex file.
You will need
the: Multi
Chip Programmer - for burning '508 chips
You will also need to download the programming program
PIP-02.
You should also go to the section "Burning
a Chip." This section explains how to load the PIC chip with a .hex
file.
TO RE-BURN A '508A CHIP
If you need to change the phone number, the old digits are turned into 00 00 (including the
RETLW 0E command), and the new digits are placed after the 00 00's.
This can be done until all the RETLW 0FFh locations are used. That's why you
need up to
100 RETLW 0FFh when you first burn the chip.
This concludes the Taxi Phone Project. To buy a kit, click
HERE
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