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Interrupt Functions Ensure Faster System Response
Two lines of each port C (i.e., ports C0, C1, C2 and C3) are connected to
an interrupt circuit. The "Interrupt Control Register" of the PCM-3753I
controls how these signals generate an interrupt. More than one interrupt
request signals can be generated at the same time, and then the software
can process these request signals by ISR. The multiple interrupt sources
provide the card with more capability and flexibility.
The PCM-3753I also provides "Pattern Match" interrupt function for port
A0. The card monitors the states of port A0 and compares them with a
pre-set pattern. When the received state matches the pre-set
pattern, the PCM-3753I generates an interrupt signal to the system.
"Change of State" interrupt function is provided at port B0. When any
signal line of port B0 changes its state, the card generates an interrupt to
the system to handle this event.
These interrupt functions release the CPU from the burden of pulling all
I/O points, enabling a PC to handle more I/O points with higher
performance.
3
Chapter 1
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