COP8782C datasheet(9/28 Pages) NSC

9 / 28 page

Functional Description (Continued)

TLDD11299 – 11

FIGURE 8 MICROWIREPLUS Application

bit in the CNTRL register enables the SO and SK functions

on the G Port The SK pin must be selected as an input and

the SO pin selected as an output pin by appropriately setting

up the Port G configuration register Table V summarizes

the settings required to enter the Slave mode of operation

The user must set the BUSY flag immediately upon entering

the Slave mode This will ensure that all data bits sent by

the Master will be shifted properly After eight clock pulses

the BUSY flag will be cleared and the sequence may be

repeated

(Figure 8)

TABLE V

Config

Fun

Operation

Bit

Int SK

MICROWIRE Master

TRI-STATE Int SK

MICROWIRE Master

Ext SK

MICROWIRE Slave

TRI-STATE Ext SK

MICROWIRE Slave

TIMERCOUNTER

The device has a powerful 16-bit timer with an associated

16-bit register enabling it to perform extensive timer func-

tions The timer T1 and its register R1 are each organized

as two 8-bit readwrite registers Control bits in the register

CNTRL allow the timer to be started and stopped under

software control The timer-register pair can be operated in

one of three possible modes Table VI details various timer

operating modes and their requisite control settings

MODE 1 TIMER WITH AUTO-LOAD REGISTER

In this mode of operation the timer T1 counts down at the

instruction cycle rate Upon underflow the value in the regis-

ter R1 gets automatically reloaded into the timer which con-

tinues to count down The timer underflow can be pro-

grammed to interrupt the microcontroller A bit in the control

timer underflows This allows the generation of square-wave

outputs or pulse width modulated outputs under software

control

(Figure 9)

MODE 2 EXTERNAL COUNTER

In this mode the timer T1 becomes a 16-bit external event

counter The counter counts down upon an edge on the TIO

pin Control bits in the register CNTRL program the counter

to decrement either on a positive edge or on a negative

edge Upon underflow the contents of the register R1 are

automatically copied into the counter The underflow can

also be programmed to generate an interrupt

(Figure 9)

MODE 3 TIMER WITH CAPTURE REGISTER

Timer T1 can be used to precisely measure external fre-

quencies or events in this mode of operation The timer T1

counts down at the instruction cycle rate Upon the occur-

rence of a specified edge on the TIO pin the contents of the

timer T1 are copied into the register R1 Bits in the control

as a positive edge or as a negative edge In this mode the

user can elect to be interrupted on the specified trigger

edge

(Figure 10)

TABLE VI Timer Operating Modes

CNTRL

Timer

Bits

Operation Mode

T Interrupt

Counts

765

0 0 0

External Counter wAuto-Load Reg

Timer Underflow

TIO Pos Edge

0 0 1

External Counter wAuto-Load Reg

Timer Underflow

TIO Neg Edge

0 1 0

Not Allowed

0 1 1

Not Allowed

1 0 0

Timer wAuto-Load Reg

Timer Underflow

1 0 1

Timer wAuto-Load RegToggle TIO Out

Timer Underflow

1 1 0

Timer wCapture Register

TIO Pos Edge

1 1 1

Timer wCapture Register

TIO Neg Edge

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