PWM1420A_000020020300
Rev. 1.00, 09/03, page 225 of 704
Section 9 14-Bit PWM Timer (PWMX)
This LSI has an on-chip 14-bit pulse-width modulator (PWM) timer with two output channels. It
can be connected to an external low-pass filter to operate as a 14-bit D/A converter.
9.1 Features
•
Division of pulse into multiple base cycles to reduce ripple
•
Eight resolution settings
The resolution can be set to 2, 64, 128, 256, 1024, 4096, or 16384 system clock cycles.
•
Two base cycle settings
The base cycle can be set equal to T
×
64 or T
×
256, where T is the resolution.
•
Sixteen operating clocks (by combination of eight resolution settings and two base cycle
settings)
Figure 9.1 shows a block diagram of the PWMX (D/A) module.
Select clock
Bus interface
Clock
Internal data bus
Comparator A
Comparator B
DADRA
DADRB
PWX1
Internal clock
φ
φ
/2,
φ
/64,
φ
/128,
φ
/256,
φ
/1024,
φ
/4096,
φ
/16384
PWX0
Fine–adjustment pulse addition
A
Fine–adjustment pulse addition
B
[Legend]
DACR:
DADRA:
DADRB:
DACNT:
PWMX D/A control register (6 bits)
PWMX D/A data register A (15 bits)
PWMX D/A data register B (15 bits)
PWMX D/A counter (14 bits)
DACNT
DACR
Control
logic
Base cycle compare match A
Base cycle compare match B
Base cycle overflow
Module data bus
Figure 9.1 Block Diagram of PWMX (D/A)
Summary of Contents for H8S/2437
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