Rainbow-electronics ATtiny861_V Instrukcja Użytkownika Pobierz pdf (Strona 82)

2588B–AVR–11/06

ATtiny261/461/861

The following code examples show how to do an atomic read of the TCNT0 register contents.

Reading any of the OCR0 register can be done by using the same principle.

Note: 1. The example code assumes that the part specific header file is included.

For I/O registers located in extended I/O map, “IN”, “OUT”, “SBIS”, “SBIC”, “CBI”, and “SBI”

instructions must be replaced with instructions that allow access to extended I/O. Typically

“LDS” and “STS” combined with “SBRS”, “SBRC”, “SBR”, and “CBR”.

The assembly code example returns the TCNT0H/L value in the r17:r16 register pair.

Assembly Code Example

TIM0_ReadTCNT0:

; Save global interrupt flag

in r18,SREG

; Disable interrupts

cli

; Read TCNT0 into r17:r16

in r16,TCNT0L

in r17,TCNT0H

; Restore global interrupt flag

out SREG,r18

ret

C Code Example

unsigned int TIM0_ReadTCNT0( void )

{

unsigned char sreg;

unsigned int i;

/* Save global interrupt flag */

sreg = SREG;

/* Disable interrupts */

_CLI();

/* Read TCNT0 into i */

i = TCNT0L;

i |= ((unsigned int)TCNT0H << 8);

/* Restore global interrupt flag */

SREG = sreg;

return i;

}

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Rainbow-electronics ATtiny861_V Instrukcja Użytkownika Strona 82