Timers do MCS51

  • Timers do MCS51

    • Two 16-bit Counter/Timers:
      • Up counters, can interrupt on overflow.
    • Counts:
      • CPU cycles (crystal/12).
      • External input (max. half CPU rate).
    • Four Operation Modes.

Timers do MCS51

  • Timers do MCS51

    • Timer Mode 0 :
      • Emulates 8048 counter/timer (13-bits).
      • 8-bit counter (TL0 or TL1).
      • 5-bit prescaler (TH0 or TH1).
    • Timer Mode 1 :
      • Simple 16-bit counter.
    • Timer Mode 2 :
      • 8-bit auto-reload.
      • Counter in TL0 or TL1.
      • Reload value in TH0 or TH1.
      • Provides a periodic flag or interrupt.

Timers do MCS51

  • Timers do MCS51

    • Timer Mode 3 :
      • Splits timer 0 into two 8-bit counter/timers.
      • First counter (TLO) acts like mode 0,
      • without prescaler.
      • Second counter (TH0):
        • Counts CPU cycles.
        • Uses TR1 (timer 1 run bit) as enable.
        • Uses TF1 (timer 1 overflow bit) as flag.
        • Uses Timer 1 interrupt.
      • Timer 1 (when timer 0 is in mode 3 ):
        • Counter stopped if in mode 3.
        • Running in mode 0, 1, or 2.
        • Has gate (INT1) and external input (T1), but no flag or interrupt.
        • May be used as a baud rate generator.

Timers do MCS51 – MODO 1

  • Timers do MCS51 – MODO 1

Timers do MCS51 – MODO 2

  • Timers do MCS51 – MODO 2

Timers do MCS51 – TMOD

  • Timers do MCS51 – TMOD

Timers do MCS51 – TCON

  • Timers do MCS51 – TCON

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