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文档SPRACD0说TMS320F28335内部有唯一ID?

最近看到一篇TI官方文档SPRACD《Application Report SPRACD0–December 2017 C2000™ Unique Device Number》,提到常用的C2000器件,都有32位的内部唯一ID,从F280x到F281x到F2803x到2833x,基本覆盖了目前常用的C2000芯片。

不过文档中又提了4条限制,除了2.1.2,其余几条都蛮致命的,尤其是2.1.3和2.1.4,想用它来做产品序列号可以吗?

2.1.1 Variability

The 32-bit value is not a pseudo randomly generated number, but is instead based on simple serialization
algorithms. Devices manufactured near the same time may have the same or similar MSWs, but should
typically have unique LSWs. Under typical situations, LSWs may repeat within a few hundred devices or a
few thousand. By using the MSW and LSW together the probability that a device number is repeated is
greatly reduced.

2.1.2 Static Bits

Some of the bits within the 32-bit value will generally have a fixed value of zero. Static bits reduce the
possible values for the 32-bit number. There is one static bit in the MSW and four static bits in the LSW.

2.1.3 Long-Term Reliability

The 32-bit value is not guaranteed to remain consistent across all operating conditions for the full life of
the device. If the value is used, it should be copied into an on-chip, nonvolatile location, such as the user
one-time programmable (OTP) memory or flash.

2.1.4 Not Tested

Devices are not rejected during factory test based on the 32-bit value. The consequence is that multiple
devices may be programmed with a common value, particularly all bits being zero or one, or some other
nonstandard value.

  • Because of this specific limitation on the F28335 device, one recommendation is to supplement this 32-bit value with some value that you generate in your process (maybe time stamp or batch serialization). The issue is that some of the fields in the 32-bit unique ID in the F28335 may get duplicated over time (in years) that may break the randomness. The chances of this happening is very small and to alleviate this, you may want to append the 32-bit unique ID with something else from your process.

    相关链接: e2e.ti.com/.../762048
  • 唯一ID最重要的两个属性是唯一性和不变性,如果这两点都得不到保证,真的没啥用处,要自己写OTP的话,还不如完全用自己的方案。这样看来,这个唯一ID真的没什么作用,文档写出来让人困惑,还不如直接写不支持唯一ID。
  • 这个ID对应着系列型号 比如CCS通过JTAG怎么识别出型号 就是通过ID