Part # Application Note Imaging datasheet

Part Manufacturer: ST Microelectronics

ST Microelectronics

Part Description: Serial numbering implementation


Part Details:

AN1658 ® Application Note Serial Numbering Implementation By DTV - Monitor MCU Applications Lab Introduction It is common practice to give each appliance a unique serial number or identification number. This serial number can be located in external memory, for example in EEPROM, but it can also be programmed, along with the MCU software inside the MCU program memory array. In some cases, this serial number must remain secret and unreadable by external devices. In other cases, it must be readable from the MCU by a remote PC through DDC lines or by any other way of the manufacturer s choice. This application note provides al the technical details on both the software and tools sides of how to implement such a serial numbering technique. Some hints have been taken from the on-line help of the STVP7 Visual Programming software tool. C language examples are provided, ready to be added to the source code if compiled with a Metrowerks C Compiler (any version: old Hiware, Panta or Codewarrior), but could be ported to other C compilers as wel . The examples are fitted for the ST7FLCD1 MCU, but can be applied to any other MCU with minor changes. 1 Serial Number Principle A serial number can be composed of any number of letters and /or digits. A common method is to encode the serial number as a string of ASCII characters, as follows: Serial Number 0 1 2 3 4 5 6 7 Corresponding ASCII Codes (hexa) 30h 31h 32h 33h 34h 35h 36h 37h The numbers can also be combined in pairs, to form more concise 2-digit numbers: Serial Number 0 1 2 3 4 5 6 7 Corresponding Numbers (hexa) 01h 23h 45h 67h Other encoding techniques are also possible. Encryption could even be used, so that only authorized persons can decode it. This is particularly useful when decryption keys such as those used for High-bandwidth Digital Content Protection (HDCP) are to be stored inside the MCU. 13th February 2003 Revision 1.0 1/8 This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to change without notice. Embedding the Serial Number AN1658 2 Embedding the Serial Number The serial number may need to meet certain requirements, some of which might be as follows: Embedded in the MCU, or stored in external memory (such as EEPROM) May be read from the MCU by an external device (PC through DDC for example) May be protected against read-out May be displayed along with On-Screen Display menus (OSD) May be programmed at production level or updated just before shipment Embedding the serial number inside the MCU software meets all of the above requirements, especially on the ST7FLCD1 MCU with its FLASH memory array which can be programmed anytime with minimum hardware requirements (by means of ICP or IAP). As a prerequisite, the format (size, encoding etc..) of the serial number must be known in advance. As an example, let s consider that it is encoded over a 4-character identification string, like this: char Serial_Number[4]; 2.1 Embedding the number inside MCU software 2.1.1 Fixed serial number This is by far the easiest way to implement the serial number, since it can either be programmed along with the MCU software or programmed later. If a common serial number is assigned to all appliances of the production lot, the string can be part of the normal MCU software without any specific requirements, like this:


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