msm7712 Oki Semiconductor, msm7712 Datasheet - Page 12

• Manufacturer Part Number: msm7712
• Description: Wireless Lan Baseband Controller
• Manufacturer: Oki Semiconductor

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. All modem signals are synchronized to RCK.
Modem Interface Signal Descriptions
12
MSEL
IFD[]
RXD
IFD[5:0]
RIFD[5:0]
RXD
DIAG[6:0]
MSM7712
Modem Interface
Pin Name
Oki Semiconductor
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Bidirectional
Bidirectional
Input
Output
Direction
1
IFD[5:0] to TXIF DAC
IFD[4] carries SLICE on RX
Baseband RX data from radio
FH Mbps (Low Cost)
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.
[1]
2
IFD[5:0] to TXIF
DAC and IFD[3:0] from RXADC
Recovered data (Debug out)
FH 1/2 Mbps (Normal ADC)
Description
3
IFD[5:0] to TXIF DAC (also used for Delta ADC)
Input from Delta ADC comparator
FH 1/2 Mbps (Delta ADC)