HT95C30P datasheet(22/50 Pages) HOLTEK

22 / 50 page

HT95C200/20P/300/30P

Rev. 0.10

October 1, 2002

Preliminary

Label

Bits

R/W

Function

FSKS

(2AH)

RDETF

Ring or line reversal detect interrupt flag

1: Ring or line reversal detected

0: No ring or line reversal detected

This flag is set by hardware and cleared by software.

CDETF

FSK carrier detect interrupt flag

1: An FSK carrier signal is detected

0: No valid FSK carrier signal is detected

This flag is set by hardware and cleared by software.

DOUT

This flag presents the FSK decoder output when the decoder is at op-

eration mode. This data stream includes the alternate 1 and 0 pattern,

the marking and the data.

DOUTC

This flag present the FSK decoder output like as the DOUT flag but

does not include the alternate 1 and 0 pattern.

4RO

Unused bit, read as

²0²

FSKF

FSK packet data interrupt flag

1: FSK packet data is ready

0: FSK packet data is not ready

This flag is set by hardware and cleared by software.

RINGF

This flag presents the ring coming signal. Refer to the following figure.

7RO

Unused bit, read as

²0²

FSKD

(2BH)

7~0

FSK packet data register

R D E T I

R I N G .

R _ D E T

V D D

C 1

R T I M E

R 1

L i n e

P r o t e c t i o n

N e t w o r k

T I P

R I N G

Ring or Line reversal detect

When no signal is present on the telephone line, RDETI

will be at GND and RTIME is pulled to VDD by R1. If a

line reversal occurs, the RDETI pin will become high.

This causes RTIME and internal signal R_DET to be

pulled low. The C1 and R1 ensure that the R_DET sig-

nal is low during such a time, so that processor can de-

tect it.

When a ring occurs on the line, internal signal R_DET is

permanently low, indicating the envelope of the ring. If

the frequency of the ring must be measured, C1 may be

removed, RTIME and R_DET inverter follow RDETI.

The flag RDETF will go high when the R_DET signal

falling edge is detected. This may cause a peripheral in-

terrupt if RMSK is 0 and the peripheral interrupt is en-

abled (EPERI=1).

FSK data output

The FSK decoder will decode the FSK signal on the TIP

and RING line and produce two kinds of data formats,

the serial data and the 8-bit packet data. It also provides

the FSK carrier detection signal.

To enable the FSK decoder, the F_PWDN should be

written as 0. Once the FSK carrier signal is detected, the

flag CDETF will be set to 1. This may cause a peripheral

interrupt if CMSK is 0 and the peripheral interrupt is en-

abled.

The serial FSK data is present in two formats: RAW data

and COOK data, and could be monitored by the flag

DOUT, DOUTC, respectively.

The flag DOUT presents the output of the decoder when

the decoder is at operation mode. This data stream in-

cludes the alternate 1 and 0 pattern, the marking and

the data.

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