Panasonic MN101C77C User Manual

VI - 41

Chapter 6 8-bit Timers

Cascade Connection

6-10-2

Setup Example

Cascade Connection Timer Setup Example (Timer 0 + Timer 1)

Setting example of timer function that an interrupt is constantly generated by cascade connection of

timer 0 and timer 1, as a 16-bit timer is shown. An interrupt is generated in every 2500 cycles (1 ms) by

selecting source clock to fs/4 (fosc=20 MHz at operation).

An example setup procedure, with a description of each step is shown below.

(1)

Set the TM0EN flag of the timer 0 mode

timer 1 mode register to "0" to stop timer 0 and

timer 1 counting.

(2)

Set both of the TM0PWM flag and TM0MOD

flag of the TM0MD register to "0" to select the

normal operation of timer 0.

(3)

Set the TM1CAS flag of the TM1MD register to

"1" to connect timer 1 and timer 0 in cascade

connection.

(4)

Set the clock source to prescaler output by

the TM0CK2-0 flag of the TM0MD register.

(5)

Set the prescaler output to fs/4 by the

TM0PSC1-0, TM0BAS flag of the timer 0

prescaler selection register (CK0MD).

Also, set the PSCEN flag of the prescaler

control register (PSCMD) to "1" to enable the

prescaler counting.

(6)

Set the timer 1 compare register + timer 0

compare register (TM1OC + TM0OC) to the

interrupt generation cycle (x'09C3' : 2500

cycles - 1).

At that time, timer 1 binary counter + timer 0

binary counter (TM1BC + TM0BC) are

initialized to x'0000'.

Setup Procedure

(1)

Stop the counter.

TM0MD (x'3F54')

bp3

:TM0EN

= 0

TM1MD (x'3F55')

bp3

:TM1EN

= 0

(2)

Select the normal operation lower

timer.

TM0MD (x'3F54')

bp4

:TM0PWM = 0

bp5

:TM0MOD

= 0

(3)

Set the cascade connection.

TM1MD (x'3F55')

bp4

:TM1CAS

= 1

(4)

Select the count clock source.

TM0MD (x'3F54')

bp2-0

:TM0CK2-0 = 001

(5)

Select the prescaler output and

enable counting.

CK0MD (x'3F56')

bp2-1

:TM0PSC1-0= 01

bp0

:TM0BAS

= 1

PSCMD (x'3F6F')

bp0

:PSCEN

= 1

(6)

Set the interrupt generation cycle

TMnOC(x'3F53', x'3F52')=x'09C3'

Description