Filter
Top Products
11-1
CHAPTER 11
EVENT PROCESSOR ARRAY (EPA)
Control applications often require high-speed event control. For example, the controller may need
to periodically generate pulse-width modulated outputs or an interrupt. 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.
11.1 EPA FUNCTIONAL OVERVIEW
The EPA performs input and output functions associated with two timer/counters, timer 1 and
timer 2 (Figure 11-1). 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 timer/counter value matches the stored value, the EPA can trigger an event:
a timer reset, an A/D conversion, a waveform generator reload, or an output event (set a pin, clear
a pin, toggle a pin, or take no action). This is called an output compare.
Each input capture or an output compare sets an interrupt pending bit. This bit can optionally
cause an interrupt. Table 11-1 lists the capture/compare and compare-only channels for each de-
vice in the 8XC196Mx family.
Table 11-1. EPA Channels
Device Capture/Compare Channels Compare-only Channels
8XC196MC EPA3:0 COMP3:0
8XC196MD EPA5:0 COMP5:0
8XC196MH EPA1:0 COMP3:0