MCIMX27 Datasheet, PDF (377/1650 Pages) Freescale Semiconductor, Inc – Multimedia Applications Processor

Chapter 14
IC Identification (IIM)
The IC Identification Module (IIM) provides an interface for reading and, in some cases, programming
and/or overriding identification and control information stored in on-chip fuse elements.
The IIM also provides a set of volatile software-accessible signals that can be used for software control of
hardware elements, not requiring non-volatility.
14.1 Overview
The IIM provides the primary user-visible mechanism for interfacing with on-chip fuse elements. Among
the uses for the fuses are unique chip identifiers, mask revision numbers, cryptographic keys, and various
control signals requiring permanent non-volatility. The IIM also provides up to 28 volatile control signals.
The IIM consists of a master controller and a set of registers to hold the values of signals visible outside
the module. Up to eight arrays of fuses (e-Fuses) are associated with the IIM.
The IIM is accessible using an 8-bit IP bus interface. An 8-bit interface is used because it matches the
natural width of the fuse arrays.
14.1.1 Features
• Up to eight independent fuse banks (number of fuse banks and size of the bank are parameterized)
• Maximum usable fuse bank size is 2048 bits
• Laser- and e-Fuse banks may be intermixed on a per bank basis
• Support for driving secure JTAG challenge and response values to the SJC (size of each field
configurable using RTL parameter; challenge default size is 64 bits, response default size is 56 bits)
• Up to 28 externally visible software-controlled volatile signals (driving SoC-level nets for feature
enabling) lockable in groups of 7
• Ability to provide up to two distinct 168-bit 3DES keys from a single set of fuses
• Ability to override fuse values in software (does not affect the fuse element); override capability
can be permanently disabled on a per-bank basis
• Ability to write-protect e-Fuses on a per-bank basis
• Ability to scan-protect (read and program) on a per-bank basis
• Fuses may be programmed by software, directly by JTAG, or indirectly by JTAG using a processor
• Recommended signal assignments to maximize software re-use
MCIMX27 Multimedia Applications Processor Reference Manual, Rev. 0.2
Freescale Semiconductor
14-1