XECOM XE1212C Datasheet

Loading...

xecom

XE1212C

6/97

1200bps Modem Module with Parallel Host Interface

Description

The XE1212C is a complete 1200/300 bps Modem in a compact, component form factor. It contains all circuitry necessary for complete modem functionality, including an FCC Part 68 Registered Data Access Arrangement (DAA) for direct connection to the telephone line, and a parallel 8250B UART interface for direct operation with the IBM-PC, XT or AT system bus. It operates from the industry standard 'AT' command set. The XE1212C contains all signal processing functions, including the modulators and demodulators for both PSK and FSK operation, and analog filters.

The XE1212C includes the capability for call progress monitoring and DTMF tone generation as well as the guard tones handling required for CCITT V.22/V.21 communications. It operates in the asynchronous mode and provides analog loopback, digital loopback and remote digital loopback functions for testing.

Features

Small Size -2.28" x 1.0" x 0.5"

FCC Part 68 Registered

212A/103 and CCITTV.22/V.21 Compatible

Industry Standard "AT" Command Set

Parallel Interface Emulates 8250B UART

Call Progress Monitoring

DTMF and Pulse Dialing

Software Controlled Audio Output

Modem Configuration storage in NVRAM

+5 Volt Power Only

Typical Operating Power 200 mW

Automatic Sleep mode when idle reduces power consumption to only 50 mW.

Block Diagram

PIN CONFIGURATION

 

N/C

 

 

 

 

 

1

40

TIP

 

GND

2

 

 

 

 

Vcc

3

 

 

 

 

RI\

4

 

37

RING

 

N/C

5

 

 

 

 

N/C

6

 

 

 

 

N/C

7

 

 

 

 

N/C

8

 

 

 

 

OH

9

 

 

 

 

N/C

10

 

 

 

N/C

11

 

 

 

AUDIO

12

 

 

 

INT

13

28

D0

 

A0

14

27

D1

 

A1

15

26

D2

 

A2

16

25

D3

 

CS\

17

24

D4

 

DOST\

18

23

D5

 

DIST\

19

22

D6

 

EHC

20

21

D7

 

 

 

 

 

 

 

 

 

 

 

 

XECOM

XE1212C

Mechanical Specifications

 

Inches

Milimeters

 

Min

Max

Min

Max

A

2.255

2.305

57.2

58.6

B

0.985

1.015

25.0

25.8

C

0.490

0.510

12.4

13.0

D

0.890

0.910

22.6

23.1

E

1.890

1.910

48.0

48.5

F

0.125

0.200

3.1

5.1

G

0.040

0.060

1.0

1.5

H

0.180

0.200

4.5

5.1

J

0.090

0.110

2.3

2.8

 

 

 

 

 

Pins = 0.020" X 0.014"

All pins tin-plated

Recommended hole size = 0.045"

Pin Descriptions

 

PIN

NAME

DESCRIPTION

 

1

N/C

No Connect.

 

2

GND

Ground Reference (0 volts).

 

3

VCC

Positive Supply Voltage (+5 volts).

 

4

\RI

Ring Indication. A low level on this status line indicates the presence of the ring cycle on

 

 

 

Tip and Ring. This line is normally used for test/status only.

 

5,6,7,8

N/C

No Connect

 

9

OH

This signal allows the user to monitor the status of the hookswitch relay in the XE1212C.

 

 

 

When the signal on OH is high, the relay is closed, and the XE1212Csiezes the telephone

 

 

 

line. During rotary dialing, this line is pulsed at a rate of 10 pulses per second.

 

10,11

N/C

No Connect

 

12

AUDIO

A programmable attenuator that can drive a load impedance of 300 ohms is provided on

 

 

 

this pin to allow monitoring of the telephone line signal through an external speaker. The L

 

 

 

and M commands adjust speaker volume and control when the audio signal will be

 

 

 

presented. The Audio Output in conjunction with an external audio amplifier (such as an

 

 

 

LM386) can drive a low impedance speaker.

 

13

INT

The Interrupt Line goes high whenever any of the enabled interrupts in the Interrupt Enable

 

 

 

Register (IER) is active. The interrupts are Received Data Available, Transmitter Holding

 

 

 

Register Empty, Receiver Line Status and Modem Status. The Interrupt Line is reset upon

 

 

 

the appropriate interrupt servicing. This pin is forced to a Hi-Z state when bit 3 bit of the

 

 

 

modem control register (MCR) is low (power on state).

 

14-16

A0..A2

These 3 address inputs select a UART register during read or write operations as shown in

 

 

 

Table 1. The Divisor Latch Access Bit (DLAB) of the LCR register must be set high by the

 

 

 

system software to access the bit rate Divisor Latch (DLM) as shown in Table 2.

 

 

 

 

XECOM

(2)

XE1212C

Pin Descriptions

 

PIN

NAME

DESCRIPTION

 

 

 

 

 

 

 

 

17

\CS

The XE1212C is selected when Chip Select is driven low. When high, the data bus lines

 

 

 

(D0..D7) will be in the high impedance state.

 

18

\DOST

The CPU can write data or control words into a selected register of the XE1212C when

 

 

 

DOST and CS are low. Data is latched on the rising edge of the signal.

 

19

\DIST

The CPU can read data or status from a selected register of the when DIST and CS are

 

 

 

low.

 

 

 

20

EHC

External Handset Control. This pin is used to control an additional relay to connnect a

 

 

 

telephone handset to the telephone line. During data transmission, when the internal relay

 

 

 

in the DAA is closed (off hook), this pin is high. When the internal relay is open (on-hook),

 

 

 

this pin is low and may be used to close an external relay to connect the telephone handset

 

 

 

to the line.

 

 

 

21-28

D7-D0

This eight bit data bus provides bidirectional communications between the modem and

 

 

 

CPU. Data, Control words and Status information are transferred on these bus lines.

 

 

 

These are tri-state lines and have internal drive buffers eliminating the need for external

 

 

 

buffering between the CPU bus and the XE1212C.

 

37,40

RING/TIP

These are the TIP and RING connections to the telephone line from the DAA. In order to

 

 

 

maintain the high voltage isolation provided by the DAA, traces from these pins to the

 

 

 

RJ11C Jack should have a minimum spacing of 100 mils between them and any other

 

 

 

traces on the board.

 

 

 

 

 

 

 

 

 

 

 

ABSOLUTE MAXIMUM RATINGS*

 

 

 

 

 

SUPPLY VOLTAGE - Vcc

+6 Volts

 

 

 

DC INPUT VOLTAGE

-0.6 Volts to (Vcc +0.6 Volts)

 

 

STORAGE TEMPERATURE RANGE

-25° C TO +85° C

 

 

 

LEAD TEMPERATURE

260° C

 

 

(Soldering, 2 seconds per wave)

 

 

 

 

OPERATING TEMPERATURE RANGE

0 TO 70° C

*Exceeding these values may result in permanent damage to the device.

XECOM

(3)

XE1212C

Typical Connection Diagram

XE1212C

IBM-PC Bus Interface Address Decoder

XE1212C

XECOM

(4)

XE1212C

UART Register Function Summary

Register Address

 

0

0

1

2

3

4

5

6

0

1

 

(DLAB=0)

(DLAB=0)

(DLAB=0)

 

 

 

 

 

(DLAB=1)

(DLAB=1)

 

 

 

 

 

 

 

 

 

 

 

 

Receiver

Transmitter

Interrupt

Interrupt

Line

Modem

Line

Modem

Divisor

Divisor

Bit

Buffer

Holding

Enable

Indent.

Control

Control

Status

Status

Latch

Latch

No.

Register

Register

Register

Register

Register

Register

Register

Register

(DLL)

(DLM)

 

(RBR)

(THR)

(IER)

(IIR)

(LCR)

(MCR)

(LSR)

(MSR)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Enable

"0" if

Word Length

Data

 

 

 

 

0

Data Bit

Data Bit

RXD

Interrupt

Selection

Terminal

Data

Delta

Bit 0

Bit 8

 

0*

0*

Available

Pending

Bit 0

Ready

Ready

CTS

 

 

 

 

 

Interrupt

 

 

(DTR)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Enable

 

 

 

 

 

 

 

 

 

 

Transmitter

Interrupt

Word Length

Request

Overrun

Delta

 

 

1

Data Bit

Data Bit

Holding

Ident.

Selection

to Send

Error

DSR

Bit 1

Bit 9

 

1

1

Reg. Empty

Bit 0

Bit 1

(RTS)

(OE)

 

 

 

 

 

 

Interrupt

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Enable

 

 

 

 

Trailing

 

 

 

 

 

Receiver

Interrupt

Stop Bits

Output 1

Parity

Edge

 

 

2

Data Bit

Data Bit

Line Status

Ident.

0=1 SB

 

Error

Ring

Bit 2

Bit 10

 

2

2

Interrupt

Bit 1

1=2 SB

 

(PE)

Indicator

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Enable

 

Parity

 

Framing

Delta

 

 

3

Data Bit

Data Bit

Modem

0

Enable

Output 2

Error

Rx Line

Bit 3

Bit 11

 

3

3

Status

 

1=PEN

 

(FE)

Signal

 

 

 

 

 

Interrupt

 

 

 

 

Detect

 

 

 

 

 

 

 

 

 

 

 

 

 

4

Data Bit

Data Bit

0

0

Even Parity

Local

Break

Clear to

Bit 4

Bit 12

 

4

4

 

 

Select

Loopback

Interrupt

Send

 

 

 

 

 

 

 

1=EPS

 

 

(CTS)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Stick

 

Transmit

 

 

 

5

Data Bit

Data Bit

0

0

Parity

0

Holding

Data Set

Bit 5

Bit 13

 

5

5

 

 

1=SP

 

Register

Ready

 

 

 

 

 

 

 

 

 

Empty

(DSR)

 

 

 

 

 

 

 

 

 

(THRE)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Transmit

 

 

 

 

 

 

 

 

Set

 

Shift

Ring

 

 

6

Data Bit

Data Bit

0

0

Break

0

Register

Indicator

Bit 6

Bit 14

 

6

6

 

 

1=SB

 

Empty

(RI)

 

 

 

 

 

 

 

 

 

(TSRE)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Divisor

 

 

Received

 

 

 

 

 

 

 

Latch

 

 

Line

 

 

7

Data Bit

Data Bit

0

0

Access

0

0

Signal

Bit 7

Bit 15

 

7

7

 

 

Bit

 

 

Detect

 

 

 

 

 

 

 

(DLAB)

 

 

 

 

 

*Bit 0 is the least significant bit. It is the first bit serially transmitted or received.

XECOM

(5)

XE1212C

+ 11 hidden pages