ATMEGA640 datasheet(136/436 Pages) MICROCHIP

tên linh kiện	ATMEGA640

Giải thích chi tiết về linh kiện	8-bit Microcontroller with 16/32/64KB In-System Programmable Flash

PDF	436 Pages

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ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]

DS40002211A

Note:

1. See “About Code Examples” on page 10.

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 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 dis-

able 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;

...

ATMEGA640 bảng dữ liệu(PDF) 136 Page - Microchip Technology