AT89C5131A-RDTIL datasheet(58/184 Pages) ATMEL

58 / 184 page

AT89C5131A-L

4338F–USB–08/07

The watchdog timer function is implemented in module 4 (See Figure 31).

The PCA interrupt system is shown in Figure 29.

Figure 29. PCA Interrupt System

PCA Modules: each one of the five compare/capture modules has six possible func-

tions. It can perform:

•

16-bit capture, positive-edge triggered

•

16-bit capture, negative-edge triggered

•

16-bit capture, both positive and negative-edge triggered

•

16-bit Software Timer

•

16-bit High-speed Output

•

8-bit Pulse Width Modulator

In addition, module 4 can be used as a Watchdog Timer.

Each module in the PCA has a special function register associated with it. These regis-

ters are: CCAPM0 for module 0, CCAPM1 for module 1, etc. (see Table 50). The

registers contain the bits that control the mode that each module will operate in.

•

The ECCF bit (CCAPMn.0 where n = 0, 1, 2, 3, or 4 depending on the module)

enables the CCF flag in the CCON SFR to generate an interrupt when a match or

compare occurs in the associated module.

•

PWM (CCAPMn.1) enables the pulse width modulation mode.

•

The TOG bit (CCAPMn.2) when set causes the CEX output associated with the

module to toggle when there is a match between the PCA counter and the module's

capture/compare register.

•

The match bit MAT (CCAPMn.3) when set will cause the CCFn bit in the CCON

capture/compare register.

•

The next two bits CAPN (CCAPMn.4) and CAPP (CCAPMn.5) determine the edge

that a capture input will be active on. The CAPN bit enables the negative edge, and

CCON

0xD8

CCF4 CCF3 CCF2 CCF1 CCF0

Module 4

Module 3

Module 2

Module 1

Module 0

ECF

PCA Timer/Counter

ECCFn CCAPMn.0

CMOD.0

IE.6

IE.7

To Interrupt

priority decoder

AT89C5131A-RDTIL Datasheet(PDF) 58 Page - ATMEL Corporation

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