Rainbow-electronics ATtiny10 Bedienungsanleitung PDF herunterladen (Seite 72)

8127B–AVR–08/09

ATtiny4/5/9/10

Note: See “Code Examples” on page 5.

The code example returns the TCNT0 value in the r17:r16 register pair.

It is important to notice that accessing 16-bit registers are atomic operations. If an interrupt

occurs between the two instructions accessing the 16-bit register, and the interrupt code

updates the temporary register by accessing the same or any other of the 16-bit timer registers,

then the result of the access outside the interrupt will be corrupted. Therefore, when both the

main code and the interrupt code update the temporary register, the main code must disable the

interrupts during the 16-bit access.

The following code example shows how to do an atomic read of the TCNT0 Register contents.

Reading any of the OCR0A/B or ICR0 Registers can be done by using the same principle.

Note: See “Code Examples” on page 5.

The code example returns the TCNT0 value in the r17:r16 register pair.

The following code example shows how to do an atomic write of the TCNT0 Register contents.

Writing any of the OCR0A/B or ICR0 Registers can be done by using the same principle.

Assembly Code Example

...

; Set TCNT0 to 0x01FF

r17,0x01

r16,0xFF

TCNT0H,r17

TCNT0L,r16

; Read TCNT0 into r17:r16

r16,TCNT0L

r17,TCNT0H

...

Assembly Code Example

TIM16_ReadTCNT0:

; Save global interrupt flag

r18,SREG

; Disable interrupts

cli

; Read TCNT0 into r17:r16

in r16,TCNT0L

in r17,TCNT0H

; Restore global interrupt flag

out SREG,r18

ret

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Rainbow-electronics ATtiny10 Bedienungsanleitung Seite 72