Securing nonvolatile, nonresettable counters in embedded designs
Bernhard Linke, Maxim Integrated Products
5/15/2011 12:31 AM EDT
It is sometimes desirable for warranty reasons to count and record certain events such as power cycles, operating time, hard (pushbutton) resets, and timeouts and do so securely.
The traditional electronic counters for this purpose are built from flip-flops, using a binary code such as the one shown in Figure 1 below. The maximum count is reached when all flip flops are set, so the size of the counter is determined by the maximum number of events to be counted during the interval of interest.
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