MPC82X54AT 参数 Datasheet PDF下载

Programmable Counter Array (PCA)

The Programmable Counter Array is a special 16-bit Timer that has four 16-bit

capture/compare modules associated with it.

operate in one of four modes:

rising and/or falling edge capture (calculator of duty length for high/low pulse)

software timer

high-speed output

pulse width modulator

Each module has a pin associated with it.

Module-0 is connected to pin P3.7,

module-1 to pin P3.5,

module-2 to pin P2.0,

module-3 to pin P2.4.

The PCA timer is a common time base for all four modules and can be programmed to run at

1/12 the oscillator frequency, 1/2 the oscillator frequency, the Timer-0 overflow, or the input on

pin ECI (P3.4). The timer count source is determined from

CPS1

and

CPS0

bits in the SFR

CMOD.

Each of the modules can be programmed to

Module-0

Capture/Compare

P3.7/CEX0

Register

16 Bit

PCA

Timer/Counter

Module-1

Capture/Compare

P3.5/CEX1

Register

Module-2

Capture/Compare

P2.0/CEX2

Register

Module-3

Capture/Compare

P2.4/CEX3

Register

Programmable Counter Array

In the

CMOD

SFR, there are two additional bits associated with the PCA. One of them is

CIDL

which determines if to stop the PCA while the MCU is put under idle. The other bit is

ECF

which controls if to pass the interrupt from PCA into the MCU.

The

CCON

SFR contains the run control bit for PCA and several flags for the PCA timer and

each module. To start the PCA counting, the

CR

bit (CCON.6) must be set by software;

oppositely, clearing bit CR will shut off the PCA. There is a bit named

CF

in SFR

CCON.

The

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MPC82x54A Data Sheet

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