Intel 80C196NU, 8XC196NP manual Chapter Event Processor Array EPA, EPA Functional Overview

CHAPTER 10

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.

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. Each input capture or an output compare sets an interrupt pending bit. This bit can optionally cause an interrupt. The EPA has four capture/compare channels, EPA3:0.

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