MSM7712 View Datasheet(PDF) - Oki Electric Industry
Part Name
Description
MFG CO.
'MSM7712' PDF : 20 Pages View PDF
s MSM7712 s –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
MODEM Interface
The MSM7712 provides FH PLPC framing and the FH modem as defined by the IEEE 802.11 specifica-
tion.The radio synthesizer control pins are used for all modem options. A diagnostic port is provided
when the internal modem is used. Several options are provided by the internal FH modem selected by
the PHY_VER[MSEL] register bits. The following table shows the pin usage for various modem options.
Modem Options and Pin Connections [1]
Modem Interface
MSEL
IFD[]
RXD
FH Mbps (Low Cost)
1
IFD[5:0] to TXIF DAC
IFD[4] carries SLICE on RX
Baseband RX data from radio
FH 1/2 Mbps (Normal ADC)
2
IFD[5:0] to TXIF
DAC and IFD[3:0] from RXADC
Recovered data (Debug out)
FH 1/2 Mbps (Delta ADC)
3
IFD[5:0] to TXIF DAC (also used for Delta ADC)
Input from Delta ADC comparator
1. All modem signals are synchronized to RCK.
Modem Interface Signal Descriptions
Pin Name
IFD[5:0]
RIFD[5:0]
RXD
DIAG[6:0]
Direction
Bidirectional
Bidirectional
Input
Output
Description
If MSEL=1 (low cost for 1Mbps modem), IFD[5:0] are used to drive a 6-bit DAC at 32 MHz to provide the mod-
ulated transmit IF signal at 24 MHz. They are set to the DAC mid-value during receive. It is anticipated that a
resistor ladder DAC will be used.
If MSEL=2,3, (1/2 Mbps modem), IFD[5:0] are used to drive a 6-bit DAC at 32 MHz to provide the modulated
transmit IF signal at 24 MHz.
If MSEL=2 (1/2 Mbps modem, normal ADC) a 4-bit ADC (e.g. CA3304 type) provides digitized demodulated
data at 16 MHz as input to the baseband controller on pins IFD[3:0] during receive. The ADC outputs must
only be enabled during receive (e.g. by connecting RXC1 to the ADC output enable pin).
If MSEL=3 (1/2 Mbps modem, delta ADC), a comparator is used to compare the value of the transmit IF DAC
output to the receive demodulated signal, performing a tracing delta ADC function. The same 6-bit DAC (but
at 16 MHz) is used on IFD[5:0] as during transmit, and the comparator input is connected to the RXD pin
With MSEL=2 (1/2 Mbps modem, normal ADC) a 4-bit ADC (e.g. CA 3304 type) provides digitized demodu-
lated data at 16 MHz as input to the baseband controller on pins IFD (3:0) during receive. The ADC outputs
must only be enabled during receive (e.g. by connecting RXC) to the ADC output enable pin.
When MSEL=1 (low-cost 1 Mbps modem), the RXD pin is used for baseband data input from a radio which
has a built-in analog data slicer. The MSM7712 has a clock recovery circuitry to synchronize to the incoming
data. The recovered clock is output on a diagnostic pin for test purposes.
When MSEL=3 (1/2 Mbps modem, delta ADC), the delta comparator is input on this pin. The recovered clock
from the demodulator is output on a diagnostic pin for test purposes.
Various signals are provided on these pins as diagnostic aids. The registers PHY_CTL[DIAG] and
DEM_CTL0[DTST] select what signals are provided on these pins.
12
Oki Semiconductor
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