ATmega64A datasheet(29/392 Pages) ATMEL

Part #	ATmega64A

Description	8-bit Microcontroller with 64K Bytes In-System Programmable Flash

PDF	392 Pages

Scroll/Zoom	100%

Manufacturer	ATMEL [ATMEL Corporation]

Direct Link	http://www.atmel.com

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29 / 392 page

8160C–AVR–07/09

ATmega64A

Note:

1. See “About Code Examples” on page 8.

Care must be exercised using this option as most of the memory is masked away.

Assembly Code Example(1)

; OFFSET is defined to 0x2000 to ensure

; external memory access

; Configure Port C (address high byte) to

; output 0x00 when the pins are released

; for normal Port Pin operation

ldi

r16, 0xFF

out

DDRC, r16

ldi

r16, 0x00

out

PORTC, r16

; release PC7:5

ldi

r16, (1<<XMM1)|(1<<XMM0)

sts

XMCRB, r16

; write 0xAA to address 0x0001 of external

; memory

ldi

r16, 0xaa

sts

0x0001+OFFSET, r16

; re-enable PC7:5 for external memory

ldi

r16, (0<<XMM1)|(0<<XMM0)

sts

XMCRB, r16

; store 0x55 to address (OFFSET + 1) of

; external memory

ldi

r16, 0x55

sts

0x0001+OFFSET, r16

C Code Example

(1)

#define OFFSET 0x2000

void

XRAM_example(void)

{

unsigned char *p = (unsigned char *) (OFFSET + 1);

DDRC = 0xFF;

PORTC = 0x00;

XMCRB = (1<<XMM1) | (1<<XMM0);

*p = 0xaa;

XMCRB = 0x00;

*p = 0x55;

}

ATmega64A Datasheet(PDF) 29 Page - ATMEL Corporation

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