ATmega32U2 datasheet(111/314 Pages) ATMEL

No. de pieza	ATmega32U2

Descripción Electrónicos	8-bit Microcontroller with 8/16/32K Bytes of ISP Flash and USB Controller

PDF	314 Pages

Scroll/Zoom	100%

Fabricante Electrónico	ATMEL [ATMEL Corporation]

Página de inicio	http://www.atmel.com

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111 / 314 page

111

7799B–AVR–07/09

ATmega8U2/16U2/32U2

Note:

1. See “Code Examples” on page 6.

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.

The following code examples show how to do an atomic read of the TCNTn Register contents.

Reading any of the OCRnA/B/C or ICRn Registers can be done by using the same principle.

Assembly Code Examples

(1)

...

; Set TCNTn to 0x01FF

ldi r17,0x01

ldi r16,0xFF

out TCNTnH,r17

out TCNTnL,r16

; Read TCNTn into r17:r16

r16,TCNTnL

r17,TCNTnH

...

C Code Examples(1)

unsigned int i;

...

/* Set TCNTn to 0x01FF */

TCNTn = 0x1FF;

/* Read TCNTn into i */

i = TCNTn;

...

ATmega32U2 Datasheet(PDF) 111 Page - ATMEL Corporation