M4640-19 데이터 시트보기 (PDF) - Conexant Systems

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M4640-19

Baseband Processor for GSM Applications

Conexant Systems 

Baseband Processor

M46

IrDA Enable

SDS_TXSignal

SDS Serial Port

0

ClkEn

1

IrDA Tx Pulse

Generation

SDS_RX

Signal

0

1

ClkEn

IrDA Rx Pulse

Stretcher

Figure 6. IrDa Pulse Shaper Functional Block Diagram

SDS_Tx

Pin

SDS_RX

Pin

C121

For the SDS Port Form Register, bit[6] enables/disables the

IrDA Pulse Shaper circuit. If this bit is set to “0,” the IrDa circuit

is disabled. If the bit is set to “1,” the circuit is enabled.

Serial Out Divider Register. The Serial Out Divider Register is

a write only register that controls the baud rate of the serial port

transmit data. The baud rate is calculated as:

Sp

Po =

(So + 1)

where: Po = port output baud rate

Sp = serial port clock

So = serial out divider

The serial port clock is the output from the PTG. Note that this

register must be loaded with 0x0F if a short stop bit is to be

used or if 5-bit word length is selected.

Serial In Divider Register. The Serial In Divider Register is a

write only register that determines the baud rate at which the

serial port expects to receive data. The baud rate is calculated

as:

Sp

Pi =

(So + 1)

where: Pi = port input baud rate

Sp = serial port clock

So = serial out divider

The serial port clock is the output from the PTG. The address

and default values for the Serial Port Form Register are

specified in Table 2.

Infrared Data Adapter (IrDA) Pulse Shaper

The IrDA Pulse Shaper allows an IrDA-compatible transceiver to

be connected directly to the SDS pins on the BP. Enabling the

Pulse Shaper inserts an IrDA-compliant Pulse Shaper between

the SDS signals and the SDS pins. The IrDA block is enabled by

setting bit [6] in the SDS Port Serial Form Register.

A functional block diagram for the operation of the Pulse Shaper

is provided in Figure 6.

When the IrDA block is enabled, the following occurs:

1. Using the bit stream output from the SDS Serial Port block

on the SDS_RX signal, the IrDA Tx Pulse Shaper

generates a short positive pulse for every “0” transmitted by

the port and a low level pulse for every “1” transmitted by

the port. The duration of pulse is programmable. The

output of the Tx Pulse Shaper is routed to the SDS_TX pin.

2. If the IrDA RX Pulse Stretcher recognizes a pulse of the

expected duration on the SDS_RX pin, a “0” is generated

on the SDS_RX signal for one bit period. If no pulse is

detected, a “1” is generated for the duration of the bit

period. The expected duration of the received pulse is

programmable.

100779C

Conexant

Proprietary Information and Specifications are Subject to Change

21

June 14, 2000

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