Книга: Advanced PIC Microcontroller Projects in C

Project PDL

Project PDL

The PDL of the project is shown in Figure 6.35. The program is in two sections: the main program and the interrupt service routine. Inside the main program, TMR0 is configured to generate interrupts every 5ms and the counter is incremented with a one-second delay. Inside the interrupt service routine, the timer interrupt is reenabled and the display digits are refreshed alternately every 5ms.

MAIN PROGRAM:
 START
  Configure PORTB as outputs
  Configure PORTC as outputs
  Clear variable Cnt to 0
  Configure TMR0 to generate interrupts every 5ms
  DO FOREVER
   Increment Cnt between 0 and 99
   Delay 1 second
  ENDDO
 END
INTERRUPT SERVICE ROUTINE:
 START
  Re-configure TMR0
  IF Digit 1 updated THEN
   Update digit 2
  ELSE
   Update digit 1
  END
 END

Figure 6.35: PDL of the project

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