Datasheet

72
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
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.
Note: See “Code Examples” on page 5.
The code example requires that the r17:r16 register pair contains the value to be written to TCNT0.
11.10.1 Reusing the Temporary High Byte Register
If writing to more than one 16-bit register where the high byte is the same for all registers written, then the high byte
only needs to be written once. However, note that the same rule of atomic operation described previously also
applies in this case.
11.11 Register Description
11.11.1 TCCR0A – Timer/Counter0 Control Register A
• Bits 7:6 – COM0A1:0: Compare Output Mode for Channel A
• Bits 5:4 – COM0B1:0: Compare Output Mode for Channel B
The COM0A1:0 and COM0B1:0 control the behaviour of Output Compare pins OC0A and OC0B, respectively. If
one or both COM0A1:0 bits are written to one, the OC0A output overrides the normal port functionality of the I/O
pin it is connected to. Similarly, if one or both COM0B1:0 bit are written to one, the OC0B output overrides the nor-
mal port functionality of the I/O pin it is connected to.
Note, however, that the Data Direction Register (DDR) bit corresponding to the OC0A or OC0B pin must be set in
order to enable the output driver.
Assembly Code Example
TIM16_WriteTCNT0:
; Save global interrupt flag
in r18,SREG
; Disable interrupts
cli
; Set TCNT0 to r17:r16
out TCNT0H,r17
out TCNT0L,r16
; Restore global interrupt flag
out SREG,r18
ret
Bit 7 6 5 4 3210
0x2E COM0A1 COM0A0 COM0B1 COM0B0
– – WGM01 WGM00 TCCR0A
Read/Write R/W R/W R/W R/W R R R/W R/W
Initial Value 0 0 0 0 0 0 0 0