/ extended interconnect testing operations will involve a combination of
two elementary modes: observability and controllability. In general terms,
the principle of operation requires but a few basic connections, which may
Figure 1 illustrates the connections required to enable the observability
of any analog pin at AT2, which may take place with (as shown) or without
the core connected to the pin.
controllability of an analog pin may take place with or without the core
connected to the pin. Figure 2 shows an example where an analog pin is
controlled by AT1 and the core is disconnected from the pin.
reader should notice that controllability and observability may be carried
out simultaneously, by merging the operating modes illustrated above in
figures 1 and 2.