NSAM265SF datasheet(16/58 Pages) NSC

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20 Functional Description (Continued)

28 FLASHAFLASH ACCESS (NSAM265SF)

The NSAM265SF CompactSPEECH supports off-chip mem-

ory devices through Expansion Memory Up to 64 Kbytes

(64K c 8) of Expansion Memory are supported directly

Nevertheless the CompactSPEECH uses bits of the on-

chip IO port (PB) to further extend the 64 Kbytes address

space and with additional glue logic it can access up to 2

Mbytes address space

The Expansion Memory mechanism is used to connect the

NSAM265SF CompactSPEECH to AFLASH and IVS ROM

devices

ROM is connected to the CompactSPEECH using the data

bus D(07) the address bus A(015) the extended address

signals EA(1621) (EA21 serves as the ROM Output En-

able signal ROM

OE) and Expansion Memory Chip Se-

lect EMCS controls If AFLASH is connected (NSAM265SF

only) the FLASH

OE signal is also used The number of

extended address pins to use may vary depending on the

size and configuration of the ROM and AFLASH devices

Reading from Expansion Memory

An Expansion Memory read bus cycle starts at T1 when the

data bus is in TRI-STATE and the address is driven on the

address bus EMCS is asserted (0) on a T2W1 cycle This

cycle is followed by three T2W cycles and one T2 cycle

Data is sampled by the NSAM265SF at the end of the T2

cycle

The transaction is terminated at T3 when EMCS becomes

inactive (1) The address remains valid until T3 is complete

A T3H cycle is added after the T3 cycle The address re-

mains valid until the end of T3H

WR0 is inactive (1) during the read bus cycle

29 FLASHAFLASH SPECIFICATIONS

The NSAM265SF supports either the AMD Am29F040 Sec-

tor Erase Audio Flash 4-Mbit Memory or the Intel 28F008SA

8-Mbit AFLASH memory as message storage devices

These devices are organized in 64-Kbytes blocks and sup-

port up to 100000 block-erase cycles For the exact fea-

tures of these devices please refer to the devices’ specifica-

tions

AFLASH devices contain bad blocks The NSAM265SF

supports devices with more good blocks than bad blocks

at least five good blocks on the AMD device and at

least nine good blocks on the Intel device

210 FLASHAFLASH CONFIGURATIONS

The NSAM265SF supports up to two 28F008SA devices or

up to four 29F040 devices The actual configuration is se-

lected by the CFG command

Figures 2-6 2-7 2-8 and 2-9 illustrate the minimum and

maximum configurations for each device in an environment

that contains an IVS ROM

TLEE12378 – 9

FIGURE 2-6 One Intel Flash Device No External Glue Logic

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