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8051 Aula 02 Prof Afonso Ferreira Miguel. Microcontrolador 8051 (MCS-51)  Timers do MCS51 Two 16-bit Counter/Timers: Two 16-bit Counter/Timers: Up counters,

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Presentation on theme: "8051 Aula 02 Prof Afonso Ferreira Miguel. Microcontrolador 8051 (MCS-51)  Timers do MCS51 Two 16-bit Counter/Timers: Two 16-bit Counter/Timers: Up counters,"— Presentation transcript:

1 8051 Aula 02 Prof Afonso Ferreira Miguel

2 Microcontrolador 8051 (MCS-51)  Timers do MCS51 Two 16-bit Counter/Timers: Two 16-bit Counter/Timers: Up counters, can interrupt on overflow. Counts: Counts: CPU cycles (crystal/12). External input (max. half CPU rate). Four Operation Modes. Four Operation Modes.

3 Microcontrolador 8051 (MCS-51)  Timers do MCS51 Timer Mode 0 : Timer Mode 0 : Emulates 8048 counter/timer (13-bits). 8-bit counter (TL0 or TL1). 5-bit prescaler (TH0 or TH1). Timer Mode 1 : Timer Mode 1 : Simple 16-bit counter. Timer Mode 2 : Timer Mode 2 : 8-bit auto-reload. Counter in TL0 or TL1. Reload value in TH0 or TH1. Provides a periodic flag or interrupt.

4 Microcontrolador 8051 (MCS-51)  Timers do MCS51 Timer Mode 3 : Timer Mode 3 : Splits timer 0 into two 8-bit counter/timers.Splits timer 0 into two 8-bit counter/timers. First counter (TLO) acts like mode 0,First counter (TLO) acts like mode 0, without prescaler.without prescaler. Second counter (TH0):Second counter (TH0): Counts CPU cycles. Counts CPU cycles. Uses TR1 (timer 1 run bit) as enable. Uses TR1 (timer 1 run bit) as enable. Uses TF1 (timer 1 overflow bit) as flag. Uses TF1 (timer 1 overflow bit) as flag. Uses Timer 1 interrupt. Uses Timer 1 interrupt. Timer 1 (when timer 0 is in mode 3 ):Timer 1 (when timer 0 is in mode 3 ): Counter stopped if in mode 3. Counter stopped if in mode 3. Running in mode 0, 1, or 2. Running in mode 0, 1, or 2. Has gate (INT1) and external input (T1), but no flag or interrupt. Has gate (INT1) and external input (T1), but no flag or interrupt. May be used as a baud rate generator. May be used as a baud rate generator.

5 Microcontrolador 8051 (MCS-51)  Timers do MCS51 – MODO 1 Osc.÷12Osc. TL1 8-bits TF1 TH1 8-bits Interrupt Control T1 (Pin) TR1 Gate INT1 (Pin) The Gate input controls whether the Counter runs while gated bythe interrupt signal or not. C/T=0 C/T=1

6 Microcontrolador 8051 (MCS-51)  Timers do MCS51 – MODO 2 Osc.÷12Osc. TL1 8-bits TF1 TH1 8-bits Interrupt Control T1 (Pin) TR1 Gate INT1 (Pin) The Gate input controls whether the Counter runs while gated bythe interrupt signal or not. C/T=0 C/T=1

7 Microcontrolador 8051 (MCS-51)  Timers do MCS51 – TMOD

8 Microcontrolador 8051 (MCS-51)  Timers do MCS51 – TCON

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