Datasheet

• The number of bits dedicated to address high byte is selectable.

• Bus-keepers on data lines to minimize current consumption (optional).

12.6.2. Overview

With all the features the External Memory Interface provides, it is well suited to operate as an interface to

memory devices such as External SRAM and Flash, and peripherals such as LCD-display, A/D, and D/A.

When the eXternal MEMory (XMEM) is enabled, address space outside the internal SRAM becomes

available using the dedicated External Memory pins (refer to figure in Pin Configurations, table Port A

Pins Alternate Functions in section Alternate Functions of Port A, table Port C Pins Alternate Functions in

section Alternate Functions of Port C and table Port G Pins Alternate Functions in section Alternate

Functions of Port G). The memory configuration is shown in the figure below.

Figure 12-4 External Memory with Sector Select

Me mory Co nfiguration A

0x0000

0x10FF

Exte rnal Memory

(0-60K x 8)

0xFFFF

Interna l memory

SRL[2..0]

SRW11

SRW10

SRW01

SRW00

Lower se ctor

Upper s e ctor

0x1100

Me mory Co nfiguration B

0x0000

Exte rnal Memory

(0-60K x 8)

0xFFFF

Interna l memory

SRW10

0x0FFF

0x1000

Note:

Atmel AVR ATmega64A in non ATmega103 compatibility mode: Memory Configuration A is available

(Memory Configuration B N/A)

ATmega64A in ATmega103 compatibility mode: Memory Configuration B is available (Memory

Configuration A N/A)