106
4317I–AVR–01/08
AT90PWM2/3/2B/3B
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 TCNTn 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 disable
the interrupts during the 16-bit access.
Assembly Code Examples
...
;
Set TCNT
n
to 0x01FF
ldi
r17,0x01
ldi
r16,0xFF
out
TCNT
n
H,r17
out
TCNT
n
L,r16
; Read TCNT
n
into r17:r16
in
r16,TCNT
n
L
in
r17,TCNT
n
H
...
C Code Examples
unsigned int
i;
...
/*
Set TCNT
n
to 0x01FF
*/
TCNT
n
= 0x1FF;
/*
Read TCNT
n
into i
*/
i = TCNT
n
;
...
Содержание AT90PWM2
Страница 344: ...346 4317I AVR 01 08 AT90PWM2 3 2B 3B 31 1 SO24...
Страница 345: ...347 4317I AVR 01 08 AT90PWM2 3 2B 3B 31 2 SO32...
Страница 346: ...348 4317I AVR 01 08 AT90PWM2 3 2B 3B 31 3 QFN32...
Страница 347: ...349 4317I AVR 01 08 AT90PWM2 3 2B 3B...