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11AA02UIDT-I/SN 数据表(PDF) 17 Page - Microchip Technology |
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11AA02UIDT-I/SN 数据表(HTML) 17 Page - Microchip Technology |
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17 / 32 page ![]() 2013 Microchip Technology Inc. DS20005206A-page 17 11AA02UID 7.0 PREPROGRAMMED UNIQUE 32-BIT SERIAL NUMBER The 11AA02UID is programmed at the factory with a unique 32-bit serial number stored in the upper 1/4 of the array and write-protected through the STATUS register. The remaining 1,536 bits are available for application use. FIGURE 7-1: MEMORY ORGANIZATION The 4-byte serial number is stored in array locations 0xFC through 0xFF, as shown in Figure 7-2. 7.1 Manufacturer and Device Codes In addition to the serial number, a manufacturer code is stored at location 0xFA and a device identifier is stored at 0xFB. The manufacturer code is fixed as 0x29. For the 11AA02UID, the device identifier is ‘0x11’. The first ‘1’ indicates the UNI/O® bus family and the second ‘1’ indicates a 2 Kbit memory density. 7.2 Factory-Programmed Write Protection In order to help guard against accidental corruption of the serial number, the BP1 and BP0 bits of the STATUS register are programmed at the factory to ‘0’ and ‘1’, respectively, as shown in the following table: This protects the upper 1/4 of the array (0xC0 to 0xFF) from write operations. This array block can be utilized for writing by clearing the BP bits with a Write Status Register (WRSR) instruction. Note that if this is performed, care must be taken to prevent overwriting the serial number. FIGURE 7-2: SERIAL NUMBER PHYSICAL MEMORY MAP EXAMPLE 7.3 Extending the 32-bit Serial Number For applications that require serial numbers larger than 32 bits, additional data bytes can be used to pad the provided serial number to meet the required length. Any data byte values can be used for padding as the 32-bit serial number ensures the extended serial number remains unique. The padding can be performed in two ways. The first method is to pad the data in software by combining the 32-bit serial number from the 11AA02UID with fixed data. The second method is to extend the number of bytes read from the 11AA02UID to meet the required length. Table 7-1 shows example address ranges and their corresponding serial number lengths. TABLE 7-1: EXTENDED READ EXAMPLES Note: The 32-bit serial number is unique across all Microchip UID-family serial EEPROM devices. 00h C0h FFh Write-Protected Serial Number Block Standard EEPROM 7654 3 2 1 0 XXXX BP1 BP0 WEL WIP ——— — 01 —— FAh FFh Manufacturer Code 32-bit Serial Number 29h Description Data Array Address 11h 12h 34h 56h 78h Device Code Serialized Fixed Type FBh FCh FDh FEh Start Address End Address Serial Number Length 0xFC 0xFF 32 bits 0xFA 0xFF 48 bits 0xF8 0xFF 64 bits 0xF0 0xFF 128 bits 0xE0 0xFF 256 bits |
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