1998 May 11

7

Philips Semiconductors

Product specification

8-bit microcontroller with DTMF

generator and 128 bytes EEPROM

PCD3359A

6

FREQUENCY GENERATOR

A versatile frequency generator section is provided (see

Fig.4). For normal operation, use a 3.58 MHz quartz

crystal or PXE resonator. The frequency generator

includes precision circuitry for dual tone multifrequency

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

telephone sets.Their frequencies are provided in purely

sinusoidal form on the TONE output or as square waves

on the P1.7/MDY output.

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.

In case no tones are generated, or the melody function is

used, 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.

Table 3

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

6.1.2

The Melody and Port Interrupt Control Register has two functions: bit 0 defines the behaviour of the melody output; bits

4 to 7 individually enable/disable specific pairs of Port 0 interrupts. MDYCON is a R/W register.

Table 4

Melody and Port Interrupt Control Register (address 13H)

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

EPI3

EPI2

EPI1

EPI0

0

0

0

EMO

BIT

SYMBOL

DESCRIPTION

7 to 4

EPI3 to EPI0 Enable Port 0 interrupts. Bits 7 to 4 individually enable/disable specific pairs of Port 0

interrupts; see Table 6 and Section 8.2 for details.

3to1

−

These bits are set to a logic 0.

0

EMO

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

TONE output is enabled. If bit EMO = 1, then P1.7/MDY is the melody output and the

TONE output is disabled (3-state). 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 logic HIGH state.