ATXMEGA64A1 datasheet(13/99 Pages) ATMEL

13 / 99 page

8067I–AVR–04/09

XMEGA A1

7.4.4

EBI - External Bus Interface

• Supports SRAM up to

– 512K Bytes using 2-port EBI

– 16M Bytes using 3-port EBI

• Supports SDRAM up to

– 128M bit using 3-port EBI

• Four software configurable Chip Selects

• Software configurable Wait State insertion

• Clocked from the Peripheral 2x Clock at up to two times the CPU clock speed

The External Bus Interface (EBI) is the interface for connecting external peripheral and memory

to the data memory space. The XMEGA A1 has 3 ports that can be used for the EBI. It can inter-

face external SRAM, SDRAM, and/or peripherals such as LCD displays and other memory

mapped devices.

The address space, and the number of pins used, for the external memory is selectable from

256 bytes (8-bit) and up to 16M bytes (24-bit). Various multiplexing modes for address and data

lines can be selected for optimal use of pins when more or less pins is available for the EBI.

Each of the four chip selects has seperate configuration, and can be configured for SRAM,

SRAM Low Pin Count (LPC) or SDRAM. The data memory address space associated for each

chip select is decided by a configurable base address and address size for each chip celect.

For SDRAM both 4-bit SDRAM is supported, and SDRAM configurations such as CAS Latency

and Refresh rate is configurable in software.

The EBI is clocked from the Peripheral 2x Clock, running up to two times faster than the CPU

and supporting speeds of up to 64 MHz.

ATXMEGA64A1 Datasheet(PDF) 13 Page - ATMEL Corporation