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11028E–ATARM–22-Apr-13
SAM9G46
20.2.6
Product Dependencies
20.2.6.1
I/O Lines
The pins used for interfacing the External Bus Interface may be multiplexed with the PIO lines.
The programmer must first program the PIO controller to assign the External Bus Interface pins
to their peripheral function. If I/O lines of the External Bus Interface are not used by the applica-
tion, they can be used for other purposes by the PIO Controller.
20.2.7
Functional Description
The EBI transfers data between the internal AHB Bus (handled by the Bus Matrix) and the exter-
nal memories or peripheral devices. It controls the waveforms and the parameters of the
external address, data and control buses and is composed of the following elements:
the Static Memory Controller (SMC)
the DDR2/SDRAM Controller (DDR2SDRAMC)
the ECC Controller (ECC)
a chip select assignment feature that assigns an AHB address space to the external devices
a multiplex controller circuit that shares the pins between the different Memory Controllers
programmable CompactFlash support logic
programmable NAND Flash support logic
20.2.7.1
Bus Multiplexing
The EBI offers a complete set of control signals that share the 32-bit data lines, the address
lines of up to 26 bits and the control signals through a multiplex logic operating in function of the
memory area requests.
Multiplexing is specifically organized in order to guarantee the maintenance of the address and
output control lines at a stable state while no external access is being performed. Multiplexing is
also designed to respect the data float times defined in the Memory Controllers. Furthermore,
refresh cycles of the DDR2 and SDRAM are executed independently by the DDR2SDRAM Con-
troller without delaying the other external Memory Controller accesses.
20.2.7.2
Pull-up Control
The EBI_CSA registers in the Chip Configuration User Interface permit enabling of on-chip pull-
up resistors on the data bus lines not multiplexed with the PIO Controller lines. The pull-up resis-
tors are enabled after reset. Setting the EBIx_DBPUC bit disables the pull-up resistors on the D0
to D15 lines. Enabling the pull-up resistor on the D16-D31 lines can be performed by program-
ming the appropriate PIO controller.
20.2.7.3
Static Memory Controller
For information on the Static Memory Controller, refer to the Static Memory Controller section.
20.2.7.4
DDR2SDRAM Controller
For information on the DDR2SDRAM Controller, refer to the DDR2SDRAMC section.
20.2.7.5
ECC Controller
For information on the ECC Controller, refer to the ECC section.