ATmega16U4 datasheet(110/408 Pages) ATMEL

tên linh kiện	ATmega16U4

Giải thích chi tiết về linh kiện	8-bit Microcontroller with 16/32K Bytes of ISP Flash and USB Controller

PDF	408 Pages

Scroll/Zoom	100%

nhà sản xuất	ATMEL [ATMEL Corporation]

Trang chủ	http://www.atmel.com

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110 / 408 page

110

7766D–AVR–01/09

ATmega16U4/ATmega32U4

Note:

1. See “Code Examples” on page 8.

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

...

/* Set TCNTn to 0x01FF */

TCNTn = 0x1FF;

/* Read TCNTn into i */

i = TCNTn;

...

Assembly Code Example(1)

ATmega16U4 bảng dữ liệu(PDF) 110 Page - ATMEL Corporation