1996 Dec 18

7

Philips Semiconductors

Product specification

8-bit microcontrollers with DTMF

generator and 256 bytes EEPROM

PCA3354C; PCD3354A

6

FREQUENCY GENERATOR

A versatile frequency generator section with built-in

programmable clock divider is provided (see Fig.3).

The clock divider allows the DTMF section to run either

control bit DIV3 (see Table 5). The frequency generator

includes precision circuitry for dual tone multifrequency

(DTMF) signals, which is typically used for tone dialling

telephone sets.

The TONE output can alternatively issue twelve modem

frequencies for data rates between 300 and 1200 bits/s.

In addition to DTMF and modem frequencies, two octaves

of musical scale in steps of semitones are available. Their

frequencies are provided either in purely sinusoidal form

on the TONE output or as a square wave on the port line

P1.7/MDY. The latter is typically for ringer applications in

telephone sets. If no frequency output is selected the

TONE output is in 3-state mode.

6.1

Frequency generator derivative registers

6.1.1

Table 3 gives the addresses, symbols and access types of the High Group Frequency (HGF) and Low Group Frequency

(LGF) registers, used to set the frequency output.

Table 3

Hexadecimal addresses, symbols, access types and bit symbols of the frequency registers

6.1.2

Table 4

Clock and Melody Control Register, MDYCON (address 13H; access type R/W)

Table 5

Description of MDYCON bits

REGISTER

ADDRESS

REGISTER

SYMBOL

ACCESS

TYPE

BIT SYMBOLS

7

6

5

4

3

2

1

0

11H

HGF

W

H7H6H5H4H3H2H1H0

12H

LGF

W

L7L6L5L4L3L2L1L0

7

6

5

4

3

2

1

0

0

0

0

0

0

EDCO

DIV3

EMO

BIT

SYMBOL

DESCRIPTION

7to3

−

These bits are set to a logic 0.

2

EDCO

Enable DTMF clock output. If bit EDCO = 0, then DP1.7/DCO is a general purpose

derivative port line. If bit EDCO = 1, then DP1.7/DCO is the DTMF clock output.

EDCO = 1 does not inhibit the port instructions for DP1.7/DCO. Therefore the state of

both port line and flip-flop may be read in and the port flip-flop may be written by

derivative port instructions. However, the port flip-flop of DP1.7/DCO must remain set to

avoid conflicts between DTMF clock and port outputs.

1

DIV3

0

EMO

Enable Melody Output. If bit EMO = 0, then P1.7/MDY is a standard port line.

If bit EMO = 1, then P1.7/MDY is the melody output. EMO = 1 does not inhibit the port

instructions for P1.7/MDY. Therefore the state of both port line and flip-flop may be read

in and the port flip-flop may be written by port instructions. However, the port flip-flop of

P1.7/MDY must remain set to avoid conflicts between melody and port outputs.

When the HGF contents are zero while EMO = 1, P1.7/MDY is in the HIGH state.