CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Telephone Function)

4.14.2 Mask option

Output specifications for the DP terminal is selected from between complementary output and Nch open drain output by mask option.

Since the R10 to R13 terminals are used for XTMUTE, XRMUTE, HDO and HFO outputs, the output specifications of the output ports R10–R13 apply to their output specifications. Either complementary output or Nch open drain output can be selected for each terminal by the output port mask option. However, even when Nch open drain output is selected, voltage exceeding source voltage must not be applied to the output terminals.

4.14.3 Operation of telephone function

To realize the operation of the telephone function, dialing procedure is the most important concept. This procedure contains three steps: (1) setting, (2) executing and (3) interrupt.

(1)Setting

Every function has its control registers. It is necessary to set the appropriate control registers before execution. Table 4.14.3.1 lists the relations of functions and control registers.

Table 4.14.3.1 Control registers and default setting

Function

Control register

Initial setting

DTMF

TPS

(FF10H•D3)

Tone mode

 

SINC, SINR

(FF16H)

Dual tone

DP

TPS

(FF10H•D3)

Tone mode

 

MB

(FF10H•D1)

40 : 60

 

DRS

(FF10H•D0)

10 pps

 

IDP3–IDP0

(FF15H)

750 ms

PAUSE

PTS3–PTS0

(FF11H)

4 sec

FLASH

FTS3–FTS0

(FF12H)

563 ms

See Section 4.14.10, "I/O memory of telephone function", for details of each control register.

Operating mode

This dialer has built-in a DTMF generator for generating tones and a DP generator for generating dial pulses. Two basic operating modes are provided: tone mode and pulse mode. The mode can be switched by software (TPS register). This setting must be performed prior to the dial processing. At initial reset, tone mode is set.

The following operating condition should be set according to the operating mode:

Tone mode: • Selecting single tone or dual tone output

Pulse mode: • Setting a make ratio (40:60 or 33.3:66.6)

•Setting a pulse rate (10 pps or 20 pps)

•Setting an inter digit pause time (94 msec to 1,406 msec; selected from among 15 types)

Details will be discussed later.

The tone mode uses the OSC3 (3.58 MHz) clock, so the OSC3 oscillation must be turned ON (OSCC = "1") prior to dialing. However, it is not necessary to switch the CPU system clock to OSC3.

When executing the pause or flash function, the period of time should be set.

Pause time: 1 to 15 sec (1-sec units; selected from among 15 types)

Flash time: 94 msec to 1,406 msec (selected from among 15 types)

Furthermore, to use the R10 to R13 terminals for the XTMUTE, XRMUTE, HDO and HFO outputs, the output port functions must be switched to the dialer using the CTMO, CRMO, CHDO and CHFO registers (by writing "1"). This switching should be followed the procedure shown in Figure 4.14.3.1 (sample XTMUTE and XRMUTE outputs). The high impedance control registers (R10HIZ–R13HIZ) must be fixed at "0" and the data registers (R10–R13) at "1" before writing "1" to the CTMO, CRMO, CHDO and CHFO registers. Also the mute control registers (CTMUT, CRMUT) should be set to "1".

S1C63558 TECHNICAL MANUAL

EPSON

113