Datasheet

113
7728G–AVR–06/10
ATtiny87/ATtiny167
12.3.1 Code Examples
The following code examples show how to access the 16-bit timer registers assuming that no
interrupts updates the temporary register. The same principle can be used directly for access-
ing the OCR1A/B and ICR1 Registers. Note that when using “C”, the compiler handles the
16-bit access.
Note: 1. The example code assumes that the part specific header file is included.
The assembly code example returns the TCNT1 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 regis-
ters, 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 dis-
able the interrupts during the 16-bit access.
Assembly Code Examples
(1)
...
; Set TCNT1 to 0x01FF
ldi r17,0x01
ldi r16,0xFF
sts TCNT1H,r17
sts TCNT1L,r16
; Read TCNT1 into r17:r16
lds r16,TCNT1L
lds r17,TCNT1H
...
C Code Examples
(1)
unsigned int i;
...
/* Set TCNT1 to 0x01FF */
TCNT1 = 0x1FF;
/* Read TCNT1 into i */
i = TCNT1;
...