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AM29PL320DB60RWPI 数据表(PDF) 20 Page - SPANSION |
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AM29PL320DB60RWPI 数据表(HTML) 20 Page - SPANSION |
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20 / 50 page ![]() 18 Am29PL320D October 2, 2003 SecSi ™ (Secured Silicon) Sector Flash Memory Region The SecSi (Secured Silicon) Sector feature provides a Flash memory region that enables permanent part identification through an Electronic Serial Number (ESN). The SecSi Sector is a minimum of 128 words (64 double words) in length, and uses a SecSi Sector Indicator Bit (DQ7) to indicate whether or not the SecSi Sector is locked when shipped from the factory. This bit is permanently set at the factory and cannot be changed, which prevents cloning of a factory locked part. This ensures the security of the ESN once the product is shipped to the field. Current version of de- vice has 512 words; future versions will have only 128 words. This should be considered during sys- tem design. AMD offers the device with the SecSi Sector either factory locked or customer lockable. The factory- locked version is always protected when shipped from the factory, and has the SecSi (Secured Silicon) Sec- tor Indicator Bit permanently set to a “1.” The cus- tomer-lockable version is shipped with the SecSi Sector unprotected, allowing customers to utilize the that sector in any manner they choose. The customer- lockable version has the SecSi (Secured Silicon) Sec- tor Indicator Bit permanently set to a “0.” Thus, the SecSi Sector Indicator Bit prevents customer-lockable 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. |
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