Thread: Having Trouble with Timer (8051) - any help appreciated

  1. #1
    Registered User
    Join Date
    Oct 2012

    Having Trouble with Timer (8051) - any help appreciated

    I am working on a program that takes an input from a switch (connected to P0.0) and causes 4 LEDs to blink. I am using an Atmel 8051 microcontroller. The idea is that if P0.0 is one then the LEDs will blink from lowest to highest with a .25 second delay between blinks. Only one LED will be on at a time. If P0.0 is zero then the LEDs will blink from highest to lowest with a .25 seconds delay. Only one LED will be on at a time.

    The LEDs are connected to P1.0, P1.1, P1.2, P1.3.

    I have written a program in C that does exactly what the above states. I used a continuos loop that had 2 if statements in it. if(P0_0 ==0) and if(P0_0 ==1) to check the input from the switch. Each of these if statments then had code to turn a specific port on/off and delay a certain amount of time.

    My question is how would i write the code to use one of the controllers onboard timers to set the blinking delay to .25 seconds. Would i be in Timer mode 0 or 1? Would i have the clock single or double clocked?

    The crystal speed we are using is 28.2076 MHz

    Any information would be extremely helpful. Thanks in advance

  2. #2
    Registered User
    Join Date
    May 2010
    I suggest you consult your documentation for your development board and the micro-controller you are using. Check the manufacture's web site. Quite often there are some very good sample programs you can take and modify for your usage.


  3. #3
    TEIAM - problem solved
    Join Date
    Apr 2012
    Melbourne Australia
    Read section 2.9 of this -

    Don't forget to Google - Atmel 8051 timer interrupt tutorial c language

    avrfreaks is a good website for Atmel development
    Fact - Beethoven wrote his first symphony in C

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