Rainbow Electronics AT91CAP9S250A - Manual (Page 143)

143
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
21. External Bus Interface (EBI)
21.1 Description
The External Bus Interface (EBI) is designed to ensure the successful data transfer between
several external devices and the embedded Memory Controller of an ARM-based device. The
Static Memory, DDR/SDRAM, Burst CellularRAM and ECC Controllers are all featured exter-
nal 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, SDRAM ,Mobile DDR and Burst Cellular RAM.
The EBI also supports the CompactFlash and the NAND Flash protocols via integrated cir-
cuitry that greatly reduces the requirements for external components. Furthermore, the EBI
handles data transfers with up to seven external devices, each assigned to seven address
spaces defined by the embedded Memory Controller. Data transfers are performed through a
16-bit or 32-bit data bus, an address bus of up to 26 bits, up to seven chip select lines
(NCS[5:0] and SDCS) and several control pins that are generally multiplexed between the dif-
ferent external Memory Block Diagram
21.1.1 External Bus Interface
Figure 21-1 shows the organization of the External Bus Interface.