A device for simulating the operation of a traffic light on the PIC16F84A microcontroller. Scheme, description

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A device for simulating the operation of a traffic light on the PIC16F84A microcontroller. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Microcontrollers

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The traffic light simulation device is implemented on the PIC16F84A microcontroller. The switching circuit of the microcontroller (MK) is standard; a 32768 Hz resonator used in watches is used as a quartz resonator.

microcontroller datasheet PIC16F84A

(click to enlarge)

LEDs are connected to the outputs RB1..RB6 through current-limiting resistors 500 - 200 Ohm: Instead of LEDs, you can use any other lamps, but for this you need to put transistor switches or other matching devices (optorelays, optocouplers, etc.) on the microcontroller outputs

1 traffic light
RB1 - red (K1)
RB2 - yellow (W1)
RB3 - green (З1)
2 traffic light
RB4 - red (K2)
RB5 - yellow (W2)
RB6 - green (З2)

An example of compiling a program to simulate the operation of a traffic light: To compose a program, it is necessary to draw up a flowchart of work.

K1 = 1, Z2 = 1
turn on red at the first traffic light, green at the second, the rest are disabled
K1 = 1, Z2 = 0,1,0,1,0,1,0,1,0,1
red at the first traffic light continues to burn, green at the second blinks 5 times, the rest are off
K1 = 1, W1 = 1, W2 = 1
red on the first remains on, yellow on the first and second traffic lights turns on, the rest are off
K2 = 1, Z1 = 1
turn on red at the second and green at the first traffic lights, the rest are disabled
K2 \u1d 1, Z0,1,0,1,0,1,0,1,0,1 \uXNUMXd XNUMX
red at the second traffic light continues to burn, green at the first blinks 5 times, the rest are off
K2 = 1, W2 = 1, W1 = 1
red on the second continues to burn, yellow turns on at the second and first traffic lights, the rest are turned off

Program text with comments in assembler and HEX file (comments are not repeated)

A little about the program:

the inclusion of red on the first and green on the second is done by copying the constant 01000010 to PortB.
The Pause_1 subroutine serves to delay the state of the PortB pins for a time of approximately 10 seconds.
For "blinking" green, the Z_1 subroutine is used, which includes two delay subroutines using bit-oriented commands (bcf PortB,6, bsf PortB,6): 1) green off 2) green on.
Further, everything is similar.

Author: A. Kapliy, Ukraine, processor@meta.ua; Publication: cxem.net

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