Panasonic MN101C77C, F77G user manual VII 26 16-bit Standard PWM Output

Chapter 7 16-bit Timer

Setup Procedure		Description
(5) Select the count clock source.		(5) Select fosc at clock source by the TM7CK1-0
TM7MD1 (x'3F78')		flag of the TM7MD1 register. Also, select 1/1
bp1-0	: TM7CK1-0 = 00	frequency (no division) at count clock source
bp3-2	: TM7PS1-0 = 00	by the TM7PS1-0 flag.
(6) Set "H" period of the PWM output.		(6) Set "H" period of the PWM output to the timer 7
TM7PR1 (x'3F75', x'3F74')=x'4000'		preset register 1 (TM7PR1). To be a 1/4 duty
		of the full count (65536), set as follows ;
		65536 / 4 = 16384 (x'4000')
		At that time, the same value is loaded to the
		timer 7 compare register 1 (TM7OC1) and the
		timer 7 binary counter (TM7BC) is initialized to
		x'0000'.
(7) Start the timer operation.		(7) Set the TM7EN flag of the TM7MD1 register to
TM7MD1 (x'3F78')		"1" to start timer 7.
bp4	: TM7EN = 1

TM7BC counts up from x'0000'. The PWM source waveform outputs "H" until TM7BC reaches the set value of the TM7OC1 register, then, after the match it outputs "L". After that, TM7BC continues to count up, once overflow happens, the PWM source waveform outputs "H" again, and TM7BC counts up from x'0000', again. TM7IO pin outputs one count clock delay of the PWM source wave- form.

In the initial state of the PWM output, it is changed to "H" output from "L" output as the PWM operation is selected by the TM7PWM flag of the TM7MD2 register.

Write to preset register should be done while timer is stopped or within timer interrupt pro- cessing.

And use MOVW instruction for write to preset register.

VII - 26 16-bit Standard PWM Output