ata6616 ATMEL Corporation, ata6616 Datasheet - Page 137

• Manufacturer Part Number: ata6616
• Description: Microcontroller With Lin Transceiver, 5v Regulator And Watchdog
• Manufacturer: ATMEL Corporation

9132A–AUTO–10/08
DRAFT
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 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 examples show how to do an atomic read of the TCNT1 Register contents.
Reading any of the OCR1A/B or ICR1 Registers can be done by using the same principle.
The assembly code example returns the TCNT1 value in the r17:r16 register pair.
Assembly Code Example
C Code Example
Note:
TIM16_ReadTCNT1:
unsigned int TIM16_ReadTCNT1(void)
{
}
; Save global interrupt flag
in
; Disable interrupts
cli
; Read TCNT1 into r17:r16
lds
lds
; Restore global interrupt flag
out
ret
unsigned char sreg;
unsigned int i;
/* Save global interrupt flag */
sreg = SREG;
/* Disable interrupts */
_CLI();
/* Read TCNT1 into i */
i = TCNT1;
/* Restore global interrupt flag */
SREG = sreg;
return i;
1. The example code assumes that the part specific header file is included.
r18,SREG
r16,TCNT1L
r17,TCNT1H
SREG,r18
(1)
(1)
ATA6616/ATA6617 [Preliminary]
137