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M4640-19 View Datasheet(PDF) - Conexant Systems

Part NameDescriptionManufacturer
M4640-19 Baseband Processor for GSM Applications Conexant
Conexant Systems Conexant
M4640-19 Datasheet PDF : 47 Pages
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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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