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| Home > Program Trace Macrocell Programmer’s Model > PTM input resources > Extended external inputs | |||
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| Home > Program Trace Macrocell Programmer’s Model > PTM input resources > Extended external inputs | |||
The number of extended external inputs implemented by a PTM is implementation defined, and can be zero. If a PTM implements extended external inputs, it must implement:
An extended external input bus, that provides signal inputs to the PTM.
Between one and four extended external input selectors. Each selector provides a resource that you can use to define PTM events.
A control register for the extended external input selectors, see Extended External Input Selection Register, ETMEXTINSELR. You program this register to define which bit of the extended external input bus drives each of the extended external input selectors.
If you read the Configuration Code Extension Register:
bits [10:3] specify the width of the extended external input bus
bits [2:0] specify the number of extended external input selectors.
Both of these fields read-as-zero if the PTM does not implement any extended external inputs.
Figure 3.6 shows an implementation with an 8-bit wide extended external input bus and two extended external input selectors.
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