Panasonic MN101C00 User Manual

Page 86

Chapter 4 Timer Functions

■ Timer Pulse Output Function

Settings for the timer pulse output function are listed below.

(1)

Set the TM4EN flag of the timer 4 mode register (TM4MD) to "0" so that the count

operation of timer 4 is stopped.

(2)

Set bit 4 of the port 1 output/input mode register (P1OMD) to the special

function pin setting. Bit 4 of port 1 will be specified as the pulse output pin.

(3)

Use the TM4CK2 to 0 flags of the TM4MD register to select fosc, fs/4, or fs/16 as the

clock source.

(4)

Set the TM4PWM flag of the TM4MD register to "0" so that 16-bit timer operation

is selected.

(5)

Set a value in compare register 4 (TM4OCH, TM4OCL).

(6)

Set the TM4EN flag of the TM4MD register to "1" to start the timer.

(7)

When timer 4 begins operation, binary counter 4 will count upward from X'0000'.

(8)

When the value of binary counter 4 matches that of the TM4OCH and TM4OCL

registers, the timer 4 interrupt request flag is set, and the binary counter 4 is reset to

X'0000' and begins to count upward again.

Figure 4-3-3 Timer Pulse Output Timing

The period of the output signal

from the port is 1/2 of the period

set in the TM4OCH, TM4OCL

Binary
counter 4

Matches TM4OCH, TM4OCL register

TM4OUT

16-bit Timer Operation (timer 4)