Example Of Pwm Signal Output By 16-Bit Timer/Counter; Setting Of Control Registers For Pwm Output Operation - NEC PD78212 User Manual

(4) PWM output operation
In PWM output operation, a pulse signal with a duty factor determined by the value set in a compare register
is output. (See Fig. 7-35.)
The duty factor of a PWM output signal can be changed in steps of 1/65536 from 1/65536 to 65535/65536.
In addition, 16-bit timer 0 (TM0) has two compare registers, so that two types of PWM signals can be output.
Fig. 7-36 shows the setting of control registers. Fig. 7-37 shows the setting procedure. Fig. 7-38 shows the
procedure for changing the duty factor of PWM output.
Fig. 7-35 Example of PWM Signal Output by 16-Bit Timer/Counter
TM0
count value
0H
TO0
(active low)
Fig. 7-36 Setting of Control Registers for PWM Output Operation
TMC0
CRC0
TOC
PMC3
FFFFH
CR00
Timer starts
(a) Timer control register 0 (TMC0)
7 6 5 4 3
×
0 0 0
1
(b) Capture/compare control register 0 (CRC0)
7 6 5 4 3
1
1 0 0 0
(c) Timer output control register (TOC)
7 6 5 4 3
× × × × ×
(d) Port 3 mode control register (PMC3)
7 6 5 4 3
× × × ×
1
Chapter 7 Timer/Counter Units
FFFFH
CR00 CR00
2 1 0
0
0 0
Overflow flag
Enables counting TM0
2 1 0
0
0 0
Disables clearing TM0
Both TO0 and TO1 are used for
PWM output
2 1 0
×
1 1
TO0 for low-active PWM signal output
Enables PWM output for TO0
2 1 0
× × ×
Specifies P34 pin as TO0
output
FFFFH
135
7
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