MC68HC05F8 Datasheet, PDF (81/126 Pages) Motorola, Inc – High-density complementary metal oxide semiconductor(HCMOS) microcontroller unit

Freescale Semiconductor, Inc.
9
DTMF/MELODY GENERATOR
The DTMF/Melody Generator (DMG) is a multi-function tone generator built into the
MC68HC05F8 MCU, supporting DTMF dialling, melody-on-hold, and pacifier tone functions. The
associated output pins are TONEOUT and TONEX.
9.1
Features
• 4 row and 4 column frequencies for DTMF dialling
• 24 row and 24 column frequencies for dual tone melody
• 28 frequencies for pacifier tone to acknowledge button pressed for pulse dialling
• Power saving mechanism for no tone condition
• 3.579MHz ÷ 2 operation
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• 6-bit D/A converter and 28 time steps for sine wave generation
• Sine wave or square wave selectable output for melody or DTMF
• Single or dual tone capability for melody or DTMF
9.2
General Operation
In Figure 9-1, the DMG consists of a row tone and a column tone generation path. The tone
frequency of each path is controlled by their respective frequency control registers; Row
Frequency Control register (FCR) and Column Frequency Control register (FCC). At the
TONEOUT output, single/dual sine/square wave tones of DTMF and melody frequencies are
possible, whereas at the TONEX output, only single square wave tones are possible.
To generate a sine wave tone with programmable frequency in a path, the internal clock (i.e. the
3.58MHz ÷ 2) is first divided by a frequency divider, whose value is set by the frequency control
register (FCR or FCC). The output of the divider is a periodic pulse train whose frequency is the
MC68HC05F8
DTMF/MELODY GENERATOR
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TPG
MOTOROLA
9-1