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Control applications often require high-speed event control. For example, the controller may need
to periodically generate pulse-width modulated outputs, an analog-to-digital conversion, or an in-
terrupt. In another application, the controller may monitor an input signal to determine the status
of an external device. The event processor array (EPA) was designed to reduce the CPU overhead
associated with these types of event control. This chapter describes the EPA and its timers and
explains how to configure and program them.
10.1 EPA FUNCTIONAL OVERVIEW
The EPA performs input and output functions associated with two timer/counters, timer 1 and
timer 2 (Figure 10-1). In the input mode, the EPA monitors an input pin for an event: a rising edge,
a falling edge, or an edge in either direction. When the event occurs, the EPA records the value
of the timer/counter, so that the event is tagged with a time. This is called an input capture. Input
captures are buffered to allow two captures before an overrun occurs. In the output mode, the EPA
monitors a timer/counter and compares its value with a value stored in a register. When the tim-
er/counter value matches the stored value, the EPA can trigger an event: a timer reset or an output
event (set a pin, clear a pin, toggle a pin, or take no action). This is called an output compare. The
EPA sets an interrupt pending bit in response to an input capture or an output compare. This bit
can optionally cause an interrupt. Table 10-1 lists the capture/compare and compare-only chan-
nels for each device in the 8XC196Kx family.
Device
87C196CA, 8XC196J x
8XC196K x
EVENT PROCESSOR ARRAY (EPA)
Table 10-1. EPA Channels
Capture/Compare Channels
EPA3:0 & EPA9:8
EPA9:0
CHAPTER 10
Compare-only Channels
COMP1:0
COMP1:0
10-1
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