Datasheet

Table Of Contents
Section 19 14-Bit PWM
Rev. 2.00 Jul. 04, 2007 Page 436 of 692
REJ09B0309-0200
19.3.2 PWM Data Register (PWDR)
PWDR is a 14-bit write-only register. PWDR indicates the high-level width in one pulse period of
the PWM waveform when the pulse-division type PWM is selected.
When data is written to the lower 14 bits of PWDR, the contents are latched in the PWM
waveform generator and the PWM waveform generation data is updated.
PWDR is initialized to 0 and always read as H'FFFF. Writing to this register should be in a word
unit.
19.4 Operation
19.4.1 Principle of Pulse-Division Type PWM
In pulse-division type PWM, the high-level and low-level periods of the ordinary PWM waveform
are divided and output alternately. This can reduce the ripples generated when the PWM module is
used as a D/A converter by connecting a low-pass filter to it.
Figure 19.2 shows an example of waveform when the pulse is divided into four. The 14-bit PWM
module divides the pulse into 64.
One coversion period
Ordinary PWM
Pulse-division
type PWM
(Example: When
divided into four)
(1) (2) (3) (4) (5) (6) (7) (8)
(1) (2) (3) (4)(5) (6) (7) (8)
Figure 19.2 Example of Waveform Produced by Pulse-Division Type PWM (Division by 4)