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Serial EEPROM protects MAC/EUI addresses
Dan Harfert, Atmel Corp.
11/27/2012 9:00 AM EST
Storing the MAC/EUI address
One of the first considerations that system designers must make is where they will store the hardware address in the system. The most common choice is either in the nonvolatile memory of a microcontroller or in a secondary nonvolatile memory device such as a serial EEPROM. When nonvolatile memory is used to store this data, it will often contain other vital manufacturing values such as lot number, system default values, manufacturing location, system serial numbers, etc. The system designer also needs to decide how the hardware address will be protected from being altered. Ideally, a system designer can program the hardware address value during the system production operation and then apply a mechanism that for security purposes makes it impossible to alter the MAC address. Not all systems incorporate such lockout features but adding this capability to the product makes it more secure; however, in a number of applications, the extra level of security provided by ensuring the MAC cannot be altered is not a necessity.
Once an OUI has been procured from the IEEE, the next step is to create a production flow that guarantees that every individual widget has its own unique value. Here, there are numerous technical hurdles to consider. Implementing this flow can be a cumbersome task and creates a number of challenges both on the system design side as well in the manufacturing environment. The issue is further complicated if the manufacturing facility isn’t experienced in the process of managing a bank of addresses and guaranteeing no duplication of values.
From an implementation standpoint, one must decide whether the allotment of MAC/EUI values should be issued sequentially or at random. Another decision is how the database of values will be architected and how the database system that issues the MAC/EUI value confirms whether a value has been previously used. Special considerations also need to be made to handle situations in which production devices must be reworked or scrapped, including how the recovery and reuse of the MAC/EUI values should be handled when applicable, all the while guaranteeing 100% uniqueness. These issues are further compounded if there are multiple manufacturing locations that have to share the same allotment of addresses.
Adding the MAC/EUI to the device
From an execution standpoint, one must determine how the values will be transferred from the database into the actual product. Numerous approaches exist for accomplishing this. One example is to assign the MAC address for a given unit, then print it on a label and attach it to the documentation that accompanies the unit through production. Later in the production process, an operator reads the label and manually enters the value into the test equipment. That test equipment in turn writes the MAC/EUI value into device memory, usually in a microcontroller or serial EEPROM. While this method can be viable, there is a significant risk of human typographical errors. When an error like this occurs, the most common result is that the incorrect MAC/EUI address will be a duplicate value of another valid address. The problem can be magnified if the duplication is not identified until the product gets into the field.
Considering the difficulty and required experience necessary in creating and maintaining a production flow that guarantees the uniqueness of the value, particularly over multiple manufacturing locations and projects, these intangible costs can quickly surpass the fixed costs of registering an OUI with the IEEE. The combined costs of adding a MAC/EUI address can be significant, particularly in low- to medium-volume programs.
Alternatively, manufacturers may choose to avoid the headaches associated with procuring and managing a bank of addresses by using hardware with pre-installed MAC/EUI addresses. A device might contain a standard, fully user-accessible EEPROM array and a separate special read-only memory (ROM) area that stores the MAC/EUI address, for example (see figure 2). Enhanced versions might not only feature pre-programmed, guaranteed unique 48-bit or 64-bit MAC/EUI addresses but also offer manufacturers the ability to permanently write-protect a portion of the standard EEPROM array to store other factory or production process critical data. These features make it simpler, faster, and less expensive to develop Internet-connected products of all types. System manufacturers can avoid the management costs and time associated with acquiring, using and managing an allotment of MAC/EUI addresses.
With today’s emphasis on networked capabilities, embedded systems need to include unique MAC/EUI addresses to ensure functionality. Manufacturers can manage their own databases and load the numbers into the devices on the manufacturing line. Alternatively, they can work with serial EEPROM that integrates a separate area to store the MAC/EUI address. These products simplify and speed the development of new network connected products, further adding an enhanced level of quality to the production process by ensuring that no outgoing products end up with the same MAC address.
References
1. http://www.isuppli.com/home-and-consumer-electronics/news/pages/shipments-of-internet-enabled-consumer-devices-to-exceed-pcs-in-2013.aspx
About the author
Dan Harfert is a Strategic Marketing Manager in Atmel’s Memory Business Unit where he works on new product definition and technology assessment and management. He has been with Atmel since 2000. He holds a Bachelor’s Degree in Electrical and Computer Engineering as well as Master of Business Administration from the University of Colorado, Colorado Springs.
One of the first considerations that system designers must make is where they will store the hardware address in the system. The most common choice is either in the nonvolatile memory of a microcontroller or in a secondary nonvolatile memory device such as a serial EEPROM. When nonvolatile memory is used to store this data, it will often contain other vital manufacturing values such as lot number, system default values, manufacturing location, system serial numbers, etc. The system designer also needs to decide how the hardware address will be protected from being altered. Ideally, a system designer can program the hardware address value during the system production operation and then apply a mechanism that for security purposes makes it impossible to alter the MAC address. Not all systems incorporate such lockout features but adding this capability to the product makes it more secure; however, in a number of applications, the extra level of security provided by ensuring the MAC cannot be altered is not a necessity.
Once an OUI has been procured from the IEEE, the next step is to create a production flow that guarantees that every individual widget has its own unique value. Here, there are numerous technical hurdles to consider. Implementing this flow can be a cumbersome task and creates a number of challenges both on the system design side as well in the manufacturing environment. The issue is further complicated if the manufacturing facility isn’t experienced in the process of managing a bank of addresses and guaranteeing no duplication of values.
From an implementation standpoint, one must decide whether the allotment of MAC/EUI values should be issued sequentially or at random. Another decision is how the database of values will be architected and how the database system that issues the MAC/EUI value confirms whether a value has been previously used. Special considerations also need to be made to handle situations in which production devices must be reworked or scrapped, including how the recovery and reuse of the MAC/EUI values should be handled when applicable, all the while guaranteeing 100% uniqueness. These issues are further compounded if there are multiple manufacturing locations that have to share the same allotment of addresses.
Adding the MAC/EUI to the device
From an execution standpoint, one must determine how the values will be transferred from the database into the actual product. Numerous approaches exist for accomplishing this. One example is to assign the MAC address for a given unit, then print it on a label and attach it to the documentation that accompanies the unit through production. Later in the production process, an operator reads the label and manually enters the value into the test equipment. That test equipment in turn writes the MAC/EUI value into device memory, usually in a microcontroller or serial EEPROM. While this method can be viable, there is a significant risk of human typographical errors. When an error like this occurs, the most common result is that the incorrect MAC/EUI address will be a duplicate value of another valid address. The problem can be magnified if the duplication is not identified until the product gets into the field.
Considering the difficulty and required experience necessary in creating and maintaining a production flow that guarantees the uniqueness of the value, particularly over multiple manufacturing locations and projects, these intangible costs can quickly surpass the fixed costs of registering an OUI with the IEEE. The combined costs of adding a MAC/EUI address can be significant, particularly in low- to medium-volume programs.
Alternatively, manufacturers may choose to avoid the headaches associated with procuring and managing a bank of addresses by using hardware with pre-installed MAC/EUI addresses. A device might contain a standard, fully user-accessible EEPROM array and a separate special read-only memory (ROM) area that stores the MAC/EUI address, for example (see figure 2). Enhanced versions might not only feature pre-programmed, guaranteed unique 48-bit or 64-bit MAC/EUI addresses but also offer manufacturers the ability to permanently write-protect a portion of the standard EEPROM array to store other factory or production process critical data. These features make it simpler, faster, and less expensive to develop Internet-connected products of all types. System manufacturers can avoid the management costs and time associated with acquiring, using and managing an allotment of MAC/EUI addresses.
Figure 2: The AT24MAC
family of serial EEPROM devices contains pre-programmed, unique 48-bit
or 64-bit MAC/EUI addresses stored in a separate special read-only
memory area.
With today’s emphasis on networked capabilities, embedded systems need to include unique MAC/EUI addresses to ensure functionality. Manufacturers can manage their own databases and load the numbers into the devices on the manufacturing line. Alternatively, they can work with serial EEPROM that integrates a separate area to store the MAC/EUI address. These products simplify and speed the development of new network connected products, further adding an enhanced level of quality to the production process by ensuring that no outgoing products end up with the same MAC address.
References
1. http://www.isuppli.com/home-and-consumer-electronics/news/pages/shipments-of-internet-enabled-consumer-devices-to-exceed-pcs-in-2013.aspx
About the author
Dan Harfert is a Strategic Marketing Manager in Atmel’s Memory Business Unit where he works on new product definition and technology assessment and management. He has been with Atmel since 2000. He holds a Bachelor’s Degree in Electrical and Computer Engineering as well as Master of Business Administration from the University of Colorado, Colorado Springs. |
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