AM1808 datasheet(97/264 Pages) TI

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AM1808

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SPRS653 – FEBRUARY 2010

6.10 External Memory Interface A (EMIFA)

EMIFA is one of two external memory interfaces supported on the device. It is primarily intended to

support asynchronous memory types, such as NAND and NOR flash and Asynchronous SRAM. However

on this device, EMIFA also provides a secondary interface to SDRAM.

6.10.1 EMIFA Asynchronous Memory Support

EMIFA supports asynchronous:

•

SRAM memories

•

NAND Flash memories

•

NOR Flash memories

The EMIFA data bus width is up to 16-bits.The device supports up to 24 address lines and two external

wait/interrupt inputs. Up to four asynchronous chip selects are supported by EMIFA (EMA_CS[5:2]).

Each chip select has the following individually programmable attributes:

•

Data Bus Width

•

Read cycle timings: setup, hold, strobe

•

Write cycle timings: setup, hold, strobe

•

Bus turn around time

•

Extended Wait Option With Programmable Timeout

•

Select Strobe Option

•

NAND flash controller supports 1-bit and 4-bit ECC calculation on blocks of 512 bytes.

6.10.2 EMIFA Synchronous DRAM Memory Support

The device supports 16-bit SDRAM in addition to the asynchronous memories listed in Section 6.10.1. It

has a single SDRAM chip select (EMA_CS[0]). SDRAM configurations that are supported are:

•

One, Two, and Four Bank SDRAM devices

•

Devices with Eight, Nine, Ten, and Eleven Column Address

•

CAS Latency of two or three clock cycles

•

Sixteen Bit Data Bus Width

Additionally, the SDRAM interface of EMIFA supports placing the SDRAM in Self Refresh and Powerdown

Modes. Self Refresh mode allows the SDRAM to be put into a low power state while still retaining memory

contents; since the SDRAM will continue to refresh itself even without clocks from the device. Powerdown

mode achieves even lower power, except the device must periodically wake the SDRAM up and issue

refreshes if data retention is required.

Finally, note that the EMIFA does not support Mobile SDRAM devices.

Table 6-17 shows the supported SDRAM configurations for EMIFA.

Peripheral Information and Electrical Specifications

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