Rainbow-electronics ATmega8515L Uživatelský manuál stáhnout pdf (Strana 90)

ATmega8515(L)

2512A–AVR–04/02

Timer/Counter Register –

TCNT0

TheTimer/Counter Register givesdirectaccess, bothforread andwrite operations, to

theTimer/Counter unit 8-bit counter. Writing to theTCNT0 Registerblocks (removes)

the comparematch on the following timerclock. Modifying the counter(TCNT0)while

the counter isrunning, introduces a risk of missing a comparematch between TCNT0

and the OCR0 register.

Output Compare Register –

OCR0

The Output Compare Registercontains an 8-bit value that iscontinuously compared

with the counter value (TCNT0).Amatch can beused to generateanoutput compare

interrupt, or to generate a waveform output on the OC0 pin.

Timer/Counter Interrupt Mask

• Bit 1 – TOIE0: Timer/Counter0 Overflow Interrupt Enable

When theTOIE0 bit iswritten to one, and the I-bit in the Status Register isset (one), the

Timer/Counter0 Overflow interruptis enabled.The corresponding interruptis executed if

an overflow in Timer/Counter0occurs, i.e.,when theTOV0 bit isset in the

Timer/CounterInterrupt Flag Register –TIFR.

• Bit 0 – OCIE0: Timer/Counter0 Output Compare Match Interrupt Enable

When the OCIE0 bit iswrittentoone, and the I-bit in the Status Register isset (one), the

Timer/Counter0 Compare Match interruptis enabled.The corresponding interruptis

executed if a comparematch in Timer/Counter0occurs, i.e.,when the OCF0 bit isset in

theTimer/CounterInterrupt Flag Register –TIFR.

Bit 76543 210

TCNT0[7:0] TCNT0

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value00000000

Bit 76543 210

OCR0[7:0] OCR0

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value00000000

Bit 76543 210

TOIE1 OCIE1A OCIE1B – TICIE1 – TOIE0 OCIE0 TIMSK

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value00000000

1 2 ... 85 86 87 88 89 90 91 92 93 94 95 ... 222 223

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Rainbow-electronics ATmega8515L Uživatelský manuál Strana 90