AM29PL320DB70RWPI datasheet(20/49 Pages) AMD

20 / 49 page

Am29PL320D

June 13, 2005

devices from being used to replace devices that are

factory locked.

The system accesses the SecSi Sector through a

command sequence (see “Enter SecSi

™ Sector/Exit

SecSi Sector Command Sequence”). After the system

has written the Enter SecSi Sector command se-

quence, it may read the SecSi Sector by using the ad-

dresses normally occupied by the boot sectors. This

mode of operation continues until the system issues

the Exit SecSi Sector command sequence, or until

power is removed from the device. On power-up the

device reverts to sending commands to the boot sec-

tors.

Factory Locked: SecSi Sector Programmed and

Protected At the Factory

In a factory locked device, the SecSi Sector is pro-

tected when the device is shipped from the factory.

The SecSi Sector cannot be modified in any way. The

device is available preprogrammed with one of the fol-

lowing:

■ A random, secure ESN only

■ Customer code through the ExpressFlash service

■ Both a random, secure ESN and customer code

through the ExpressFlash service.

In devices that have an ESN, a Bottom Boot device will

have the 8-word (4-double word) ESN in the lowest ad-

dressable memor y area at addresses 000000h–

000003h in double word mode (or 000000h–000007h

in word mode). In the Top Boot device the starting ad-

dress of the ESN will be at the bottom of the lowest 8

Kbyte boot sector at addresses 1F8000h–1F8003h in

double word mode (or addresses FC0000h–FC0007h

in word mode).

Customers may opt to have their code programmed by

AMD through the AMD ExpressFlash service. AMD

programs the customer’s code, with or without the ran-

dom ESN. The devices are then shipped from AMD’s

factory with the SecSi Sector permanently locked.

Contact an AMD representative for details on using

AMD’s ExpressFlash service.

Customer Lockable: SecSi Sector NOT

Programmed or Locked At the Factory

If the security feature is not required, the SecSi Sector

can be treated as an additional Flash memory space,

expanding the size of the available Flash array. Cur-

rent version of device has 512 words; future ver-

sions will have only 128 words. This should be

considered during system design. The SecSi Sec-

tor can be read, programmed, and erased as often as

required. (In upcoming versions of this device, the

SecSi Sector erase function will not be available.) Note

that the accelerated programming (ACC) and unlock

bypass functions are not available when programming

the SecSi Sector.

The SecSi Sector can be locked in-system by perform-

ing the following steps:

■ Write the three-cycle Enter SecSi Sector Region

command sequence.

■ Write 60h to any address (protect command).

■ Wait 150 µs, and then write 40h to address 01h (ver-

ify command).

■ Read from address 02h. The data should be 01h.

■ Write the reset command (F0h to any address).

■ Write the four-cycle Exit SecSi Sector command se-

quence to return to reading from the array.

To verify the protect/unprotect status of the SecSi

Sector, follow the algorithm shown in Figure 1.

The SecSi Sector lock must be used with caution

since, once locked, there is no procedure available for

unlocking the SecSi Sector area and none of the bits

in the SecSi Sector memory space can be modified in

any way.

Figure 1.

SecSi Sector Protect Verify

Write Protect (WP#)

The Write Protect function provides a hardware

method of protecting certain boot sectors without

using VID.

If the system asserts VIL on the WP# input, the device

disables program and erase functions in Sector 0 (for

bottom boot) or Sector 18 (for top boot) independently

of whether those sectors were protected or unpro-

Write 60h to

any address

Write 40h to SecSi

Sector address

with A6 = 0,

A1 = 1, A0 = 0

START

RESET# =

VIH or VID

Wait 1

μs

Read from SecSi

Sector address

with A6 = 0,

A1 = 1, A0 = 0

If data = 00h,

SecSi Sector is

unprotected.

If data = 01h,

SecSi Sector is

protected.

Remove VIH or VID

from RESET#

Write reset

command

SecSi Sector

Protect Verify

complete

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