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PIC16F877 Microcontroller

  1. Feb 19, 2005 #1

    One of my projects requires my team to build a remote-controlled boat. One of the features of the boat is an indicator light feature which will blink on and off to indicate that there is this ship nearby and signal to other ships to clear away during dim light conditions (for example visibility is poor due to fog or at night). OK, now is a simple simple question.

    Can I use one of the ports (for example port RC0 of the PIC16F877) to output an oscillator output signal of a fixed frequency (the frequency, how to determine or control this frequency in the microcontroller? Is it dependent on the external crystal oscillator clock frequency?) since this port is designated as a Timer1 oscillator output?
    How does the oscillator signal output of this port look like if I program the microcontroller to output the desired frequency I want? Is it a square wave signal with logic one at 5V say, and logic 0 at 0 V? If the signal is exactly as above, then I think the LED will blink on/off which satisfy our design specifications.
    Another question on the LED, does LEDs have a frequency sensitivity that at a certain threshold frequency, it cannot change fast enough to blink on/off? Or is this limitation of the frequency dependent on how our eyes perceive it, not on the LED itself?
  2. jcsd
  3. Feb 20, 2005 #2
    Usually the microcontroller executes instructions slower then the input oscillator frequency. You can look in the documentation for this or just set a port to alternate between +5 and ground and use an oscilloscope to measure the frequency at which it switches.

    The led can turn off and on faster then our eyes can perceive. The LED does have a limit but that limit is far beyond the perception rate of human eyes.
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