Block Diagram - Hitachi H8/3637 Hardware Manual

Sine waves are output from a high-precision resistor-ladder-type D/A converter. Each cycle is
divided into 32 segments to give a stable waveform with low distortion.
• Composite or single waveform output
Register settings can select combined row-and-column-group output, or independent row-
group or column-group output.
11.1.2

Block Diagram

Figure 11.2 shows a block diagram of the DTMF generator.
f
TONED
VT
ref
Legend:
DTLR: DTMF load register
DTCR: DTMF control register
272
(1.2 MHz to 10 MHz, selectable
in 400-kHz steps)
OSC
D/A sine-wave
counter
D/A sine-wave
counter
Figure 11.2 DTMF Generator Block Diagram
Row section
Modified
programmable
divider
Feedback
Column section
Modified
programmable
divider
Feedback
DTLR
Clock 400 kHz
counter
DTCR