PD17012_15 Datasheet, PDF (159/320 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DIGITAL TUNING SYSTEM HARDWARE

µPD17012, 17P012
14. D/A CONVERTER (DAC)
The D/A converter (DAC) outputs its signal by means of PWM (Pulse Width Modulation), which varies the
duty factor.
By connecting an external lowpass filter to the D/A converter, digital signals can be converted into analog
signals.
14.1 Configuration of D/A Converter
Figure 14-1 shows the block diagram of the D/A converter.
As shown in the figure, the D/A converter consists of an output select block and a duty setting block for each
pin, and a clock generation block.
Figure 14-1. Block Diagram of D/A Converter
Control register
Data buffer
P0C1/PWM1
P0C0/PWM0
Output select
block
Output select
block
Duty setting
block
Duty setting
block
fPWM1
Clock
generation
block
fPWM0
14.2 Functional Outline of D/A Converter
The D/A converter outputs a variable-duty signal to each output pin.
The output frequency is 4.4 kHz, and the duty factor can be changed in 256 steps.
The following subsections 14.2.1 through 14.2.3 outline the function of each block of the D/A converter.
14.2.1 Output select blocks
The output select blocks specify whether each pin is used as a general-purpose output port pin or a D/A
converter pin.
The mode of each pin is selected by PWM1SEL and PWM0SEL of the PWM mode select register (refer to
14.3).
14.2.2 Duty setting blocks
The duty setting blocks output a signal whose duty factor can be changed in 256 steps.
The duty factor of each output pin is independently set by the PWM data register (PWMR0 or PWMR1:
peripheral address 04H or 05H) via the data buffer (refer to 14.4).
14.2.3 Clock generation block
The clock generation block generates a basic clock that is used to set the duty factor of the output signal.
The generated clock frequency fPWM is 1.125 MHz (refer to 14.4).
Data Sheet U10101EJ4V0DS
157