Datasheet

145
AT32UC3A
20. External Bus Interface (EBI)
Rev: 1.0.0.1
20.1 Features
• Present only on AT32UC3A0512 and AT32UC3A0256
• Optimized for Application Memory Space support
• Integrates Two External Memory Controllers:
– Static Memory Controller
– SDRAM Controller
• Optimized External Bus:
–16-bit Data Bus
– 24-bit Address Bus, Up to 16-Mbytes Addressable
– Optimized pin multiplexing to reduce latencies on External Memories
• 4 SRAM Chip Selects, 1 SDRAM Chip Selects:
– Static Memory Controller on NCS0
– SDRAM Controller or Static Memory Controller on NCS1
– Static Memory Controller on NCS2
– Static Memory Controller on NCS3
20.2 Description
The External Bus Interface (EBI) is designed to ensure the successful data transfer between
several external devices and the AT32UC3A device. The Static Memory and SDRAM Control-
lers are all featured external Memory Controllers on the EBI. These external Memory Controllers
are capable of handling several types of external memory and peripheral devices, such as
SRAM, PROM, EPROM, EEPROM, Flash, and SDRAM.
The EBI handles data transfers with up to five external devices, each assigned to five address
spaces defined by the embedded Memory Controller. Data transfers are performed through a
16-bit data bus, an address bus of up to 24 bits, up to four chip select lines (NCS[3:0]) and sev-
eral control pins that are generally multiplexed between the different external Memory
Controllers.
32058K
AVR32-01/12