PERIPHERAL INTERFACING
TRAFFIC LIGHT CONTROLLER OBJECTIVE Interfacing TRAFFIC LIGHT CONTROLLER with 8085 Microprocessor trainer kit and simulating the sequence of traffic light states.
APPARATUS REQUIRED 8085 Microprocessor trainer kit. Traffic light controller. Power Supply. Flat Ribbon Cable.
DESCRIPTION Combination of Red, Amber and Green LEDs are provided to indicate Halt, Wait and Go states for vehicles. Combination of Red and Green LEDs are provided for pedestrian crossing. 36 LEDs are arranged in the form of an intersection. At the left corner of each road, a group of 5 LEDs (Red, Amber and Green) are arranged in the form of a Tsection to control the traffic of that road. Each road is named as North N, South S, East E and West W. L1,L10, L19 and L28 (Red) are for stop signal for the vehicles on the road N,S,W and E respectively. L2,L11,L20 and L29 (Amber) indicate wait state for the vehicles on the road N,S,E and W respectively. L3,L4 and L5 (Green) are for left, straight and right turn for the vehicles on the road S. Similarly L12 - L13 - L14 , L23 - L22 - L21 and L32 - L31 - L30 simulates same function for the roads E, N & W respectively. A total of 16 LEDs (2 Red & 2 Green at each road) are provided for pedestrian crossing. L 7 - L9, L16 - L18, L25 - L27 & L34 - L36 (Green) when on allows pedestrians to cross and L 6 - L8, L15 - L17, L24 - L26 & L33 - L35 (Red) when on alarms the pedestrians to wait. To minimize the hardware pedestrians indicator LEDs (both Green and Red) are connected to some port lines (PC 4 to PC7 ) with Red inverted. Red LED’s L10 and L28 are connected to port lines PC 2 to PC3 while L1 and L19 are connected to lines PC 0 and PC1 after inversion. All other LEDs (Amber and Green) are connected to Port A and port B.
INSTALLATION PROCEDURE SDA_85M to NIFC_11 interface connection details: 1.Connect p3 on 85M to the connector C1 on the interface using a 26 core FRC. Care should be taken such that, pin1 of P3 on the kit coincides with pin1 of cable [Observe the notch on the cable connector] 2.Power connection: Connect +5v,GND to the interface. Color codes of power connection on the interface +5v - Orange, Blue, White GND - Black. 3.Enter the Program. 4.Now execute the program, Go The LEDs on the interface glow according to certain sequence.
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ASSEMBLY LANGUAGE PROGRAM ADDRES S C000 C002 C004 C006 C009 C00A C00C C00D C00E C010 C011 C012 C014 C017 C018 C019 C01C C01F C022 C024 C025 C028 C029 C02A C02B C02E
LABEL
REPEAT NEXTSTAT
DELAY L2 L1
MNEMONICS OPCODE/OPERAND MVI A,80H OUT CWR MVI E,03H LXI H,C100H MOV A,M OUT PORTA INX H MOV A,M OUT PORTB INX H MOV A,M OUT PORTC CALL DELAY INX H DCR E JNZ NEXTSTAT JMP REPEAT
3E D3 06 21 7E D3 23 7E D3 23 7E D3 CD 23 05 C2 C3
80 DB 03 00 C1
LXI MVI DCR JNZ DCX MOV ORA JNZ RET
11 0E 0D C2 1B 7A B3 C2 C9
00 30 FF
D,3000H C,FFH C L1 D A,D E L2
D8 D9 DA 1F C0 09 C0 04 C0
24 C0
22 C0
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PORT A PORT B PORT C
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PROGRAM TRACE LABEL
MNEMONICS MVI A,80H
DESCRIPTION Initializing the ports of the PPI 8255 as O/P ports by writing the control word as 80H. DATA BITS COMMENT
D7 1 I/O mode
D6 D5 0 0 Mode0
D4 0 PortA O/P
D3 0 PortC Upper O/P
D2 0 Mode0
D1 0 PortB O/P
D0 0 PortC Lower O/P
80H is moved to accumulator. REGISTERS A F 80 XX B C XX XX D E XX XX H L XX XX OUT CWR REPEAT
MVI E,03H
LXI H,C100H
Control word specify 8255. Initialize E register REGISTERS A 80 XX B XX XX D XX 03 H XX XX
the I/O function for each ports of with number of sequence. F C E L
Initialize the memory pointer at C100H .i.e. loads the 16-bit data in the register pair designated. REGISTERS A F 80 XX B C XX XX D E XX 03 H L C1 00 C100H is the memory pointer to the first data of the sequence. MEMORY C100 C101 C102 C103 C104
NEXTSTAT
MOV A,M
BF BF AF EE EE
HL memory pointer
Memory pointer content BFH is moved to accumulator. REGISTERS BF XX XX XX XX 03 C1 00 LED no PORTA bits BFH LED status
A B D H L14 1 Will not glow
F C E L L13 0
GLOW
L12 L11 L5 L4 1 1 1 1 Will not glow
L3 1
L2 1
Since Negative logic
when the portA bit is ‘1’ then LED is in OFF state, when the portA bit is ‘0’ then LED is in ON state.
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L13 will glow
INX H
Increment the HL register pair by 1.The instruction views the contents of the HL registers as a 16-bit number. No flags are affected. REGISTERS BF XX XX XX XX 03 C1 01
A B D H
F C E L
C101H is the memory pointer to input data sequence. MEMORY C100 C101 C102 C103 C104 MOV A,M
BF BF AF EE EE
HL memory pointer
Memory pointer content BFH is moved to accumulator. REGISTERS A F BF XX B C XX XX D E XX 03 H L C1 01 LED no PORTB bits BFH LED status
L32 1 Will not glow
L31 0
GLOW
L30 L29 L23 L22 1 1 1 1 Will not glow
L21 1
Since Negative Logic when the portB bit is ‘1’ then LED is in OFF state, when the portB bit is ‘0’ then LED is in ON state. OUT PORTB
L31 will glow
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L20 1
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INX H
Increment the HL register pair by 1. REGISTERS A F BF XX B C XX XX D E XX 03 H L C1 02 C102H is the memory pointer to input data sequence. MEMORY BF BF AF EE EE
C100 C101 C102 C103 C104 MOV A,M
HL memory pointer
Memory pointer content AFH is moved to accumulator. REGISTERS AF XX XX XX XX 03 C1 02 LED no LED glow PORTC bits AFH LED status
OUT PORTC
A B D H
F C E L
L33 L35
L34 L36
L24 L26
L25 L27
L15 L17
L16 L18
L6 L8
L7 L9
L28
L10
L19
L1
1
0
1
0
1
0
1
0
0
0
1
1
1
1
1
1
1
0
1
L33,L35
L25,L27
L15,L17
GLOW
GLOW
GLOW
0 L7,L9
Will GLOW not
GLOW
glow L1 L19 => glow; since positive logic. Only when ‘1’ is present in this place the LED will glow. L10 L28 => does not glow; since negative logic. This will not glow because only when ‘0’ is present in this, the LED will glow. Here ‘11’ is present hence it will not glow. L7,L9 L25,L27 => will glow; since negative logic. Here we have zero. L33,L35 L15,L17 => will have one.
glow; since positive logic. Here we
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CALL DELAY INX H
In order to make these LEDs glowing programmer/user, delay was provided. Increment the HL register pair by 1. REGISTERS A F AF XX B C XX XX D E XX 03 H L C1 03
visible
to
the
C103H is the memory pointer to input data sequence. MEMORY BF BF AF EE EE
C100 C101 C102 C103 C104
HL memory pointer
DCR E
E register was decremented number of sequence. REGISTERS A F AF XX B C XX XX D E XX 02 H L C1 03
by
1
indicating
JNZ NEXTSTAT JMP REPEAT
Now the next sequence is being looped.
remaining
Once again the three sequence are executed.
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WE EW
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Now the next sequence is being traced. When E=02 PORTS CONFIGURATION & DISPLAY. LED no
L14
L13
L12
L11
L
L4
L3
L2
1
1
0
5
PORTA bits EEH LED status
LED no PORTB bits EEH LED status
LED no LED glow PORTC bits ACH LED status
1
1
1
0
Will not glow
L32 1
L31 1
1
Since Negative logic L30 1
L29 0
0
1
L25 L27
L15 L17
0
1
1 L24,L26
GLOW GLOW
L22 1
GLOW Since Negative logic L21 1
Will not glow
Since Negative logic L24 L26
L33,L35
L23 1
GLOW
L34 L36 1
Will not glow
GLOW
Will not glow
L33 L35
1
L16 L18
L6 L8
0
1
1 L15,L17
GLOW
L20 0
GLOW Since Negative logic
L7 L9
L2
0
0 1
1 L6 L8
GLOW
L10
L19
L1
0 1
1 0
1 0
8
Will not glow
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WAITING SEQUENCE
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Now the next sequence is being traced. When E=01 PORTS CONFIGURATION & DISPLAY. LED no PORTA bits FBH LED status
L14 L13 L12 L11 1 1 1 1 Will not glow
L5 1
L4 0
GLOW Since Negative logic
LED no PORTB bits FBH LED status
L32 L31 L30 L29 1 1 1 1 Will not glow
L23 1
L3 L2 1 1 Will not glow
L22 0
L21 L20 1 1 Will not glow
GLOW Since Negative logic
LED no LED glow PORTC bits 50H LED status
L33 L35
L34 L36
1
L24 L26
L25 L27
1
L15 L17
L16 L18
0 0 L34,L36
0 1 L24,L26
1
0 0 L16,L18
GLOW
GLOW
GLOW
L6 L8
L7 L9
1
0 1 L6 L8
GLOW
L28
L10
0 0
0 0
GLOW
L19
L1
1 1 0 0 Will not glow
Thus the LEDs glow, when E=00 the sequence is terminated and next cycle starts.
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NS S N
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DELAY SUBPROGRAM DELAY
LXI D,3000H
Initialize the memory pointer at C100H .i.e. loads the 16-bit data in the register pair designated. REGISTERS A F XX XX B C XX XX D E 30 00 H L XX XX C100H is the memory pointer to the first data of the sequence. 3000 3001 3002 3003 3004
MEMORY XX XX XX XX XX
HL memory pointer
L2
MVI C,FFH
Move FFH immediately in to C register. REGISTERS A F XX XX B C XX FF D E 30 00 H L XX XX
L1
DCR C
Move FFH immediately in to C register. REGISTERS A F XX XX B C XX FE D E 30 00 H L XX XX
JNZ L1 DCX D
Loop until C = 00 Decrement the DE register pair by 1. REGISTERS A F XX XX B C XX XX D E 2F FF H L XX XX
MOV A,D
D register content 2FH is moved to accumulator. REGISTERS A F 2F XX B C XX XX D E 2F FF H L XX XX
ORA E
OR the accumulator content with E register content FF => 1111 1111 2F => 0010 1111 ----------1111 1111 => FF
JNZ L2 RET
REGISTERS A F FF XX B C XX XX D E 2F FF H L XX XX Only when DE=0000,this loop will end. Return to main program
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EXECUTION ADDRE SS C100 C101 C102 C103 C104 C105 C106 C107 C108
DATA BF BF AF EE EE FC FB FB 50
H H H H H H H H H
VERIFICATION The LEDs on the Interface glow according to the given sequence.
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