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DM336P

V.34 Integrated Data/ Fax/Voice/Speakerphone Modem Device Set

Davicom Semiconductor, Inc. 

DM336P

V.34 Integrated Data/ Fax/Voice/Speakerphone Modem Device Set

DM6383 Functional Description

1. Operating Mode Selection

The DM6383 MCU can be used with both internal and

external modems. When it works within an internal

modem, pin TEST2 and TEST1 must be in a low state.

The DM6383 includes a virtual UART and supports a

parallel interface.

When DM6383 works within an external modem, pin

TEST2 must be in a low state, and pin TEST1 must

be in high. The virtual UART will be disabled and the

RS232 serial interface, enabled.

TEST2

LOW

LOW

HIGH

TEST1

LOW

HIGH

X

System Configuration

Internal Modem

External Modem

Test Mode

2. Micro-controller (80C31) Reference

DM6383 supports a bank switch control pin to switch

external program memory between lower 64K bytes

(bank 0) and upper 64K bytes (bank 1) of 27C010.

In this mode, two instructions must be included in

software to switch bank 0 to bank 1:

i.e.,

CLR P1.3

JMP BANK 1 ADDRESS

With the same way, it can also switch back to bank 0

by

SETB P1.3

JMP BANK 0 ADDRESS

* For detailed information about micro-controller,

please see Programmer's Guide to 8031.

3. Micro-controller Register Description

a. UART Clock Register :

Address D4000H Reset State: 06H

Write Only

bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0

X dat6 dat5 dat4 dat3 dat2 dat1 0

The clock source of the virtual UART logic is fixed at

1.8432MHz. The clock is derived from the external

crystal used by the DM6383 controller. Therefore, the

UART 1.8432MHz clock must be obtained through

division. When the operating frequency of the

DM6383 controller changes, the divider should be

changed accordingly. This divider is specified by the

Configuration Register which can be written by the

DM6383 controller. The address mapping of the

register is D4000H: (DM6383 controller memory

mapping)

Bit 0: Always 0.

Bit 6-1: B6 - B1 define the clock di vider range from 2

to 64 (even number).

Bit 7: Not used.

b. UART Baud Generator Divisor Latch Register:

Address EC00H

Read only

bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0

dat7 dat6 dat5 dat4 dat3 dat2 dat1 dat0

By reading this register, the micro-controller can

monitor the value of the low byte divisor latch of the

virtual UART baud generator (see DLL in next section)

and determine the baud rate clock itself.

c. Modem Status Controller Register (MSCR):

Address E000H

Write only

bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit

0

0 0 0 0 /CTS /DSR /DCD /RI

The advantage of this register is that the modem line

status information can be passed to the virtual UART

by the micro-controller. The resulting signals are Ring

Detect (/RI), Carrier Detect (/DCD), Data Set Ready

(/DSR) and Clear To Send (/CTS).

8

Final

Version: DM336P-DS-F02

August 15, 2000

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