msm7730 Oki Semiconductor, msm7730 Datasheet - Page 15

• Manufacturer Part Number: msm7730
• Description: Wireless Lan Baseband Controller
• Manufacturer: Oki Semiconductor

––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
Radio Interface Signal Descriptions (Continued)
Modem Interface Signal Descriptions
General Signal Descriptions
DACEN
RSSITN
RCK
RXD
IFD[5:0]
RXD
DIAG[6:0]
SCK
VSSC
VSSO
VDDC
VDDO
Pin Name
Pin Name
Pin Name
Open-collector
Input
Output
Input
Bidirectional
Input
Output
Input
Ground
Power
Power
Power
Direction
Direction
Direction
For TX power control, CCA threshold and RSSI measurement, data also is clocked into a serial DAC (10/12 bit
type; e.g., MAX515/MAX539) using the SYNCLK and SYNDAT lines as described above, except that DACEN is
asserted during the programming, and the data is latched on the rising edge of DACEN.
RSSITH is an input from a threshold comparison of the analog RSSI signal from the radio with the DAC output.
It is high when the received signal exceeds the programmed threshold. This performs two purposes:
A minimum threshold of RSSI can be set before enabling the demodulator for CCA to reduce power.
Once a valid receive signal is determined (CCA invalid), the RSSI can be measured with the external
comparator/DAC and a SAR within the MSM7730. The RSSI measurement is performed for internal and
external modem options when CCA is determined.
The same DAC can be used for both TX power control, RSSI threshold and RSSI measurement.
A clock to the radio is provided on this pin. The clock is derived from SCK when RADPWR is asserted, with
fixed division ratio of one or two (selected by post-reset configuration SCK_CONF). RCK is typically 16 MHz
for the radio synthesizer reference.
The function of this pin depends on the state of the MSEL[3:0] field in the PHY_CONFIG register.
If MSEL = 1 (low cost for 1-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. 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/- 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.
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 MSM7730 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.
The system clock to the MSM7730 is provided by this pin. The clock must always be active (i.e., when reset is
asserted). The WLAN card operates synchronously to this clock.
The MSM7730 and radio operate at SCK/2. The internal modem operates at SCK (32 MHz).
The processor operates from a division of SCK (divide by 1 to divide by 8) depending on a register (GLOB_CTL,
see Programmers Reference) in the MSM7730. This signal is output as PCK.
These pins serve as ground for the core logic.
This pin serves as ground for the I/O pads.
This pin serves as power to the core at 3-V nominal.
This pin serves as power to I/O pads and can either be 3 V or 5 V nominal.
Description
Description
Description
Oki Semiconductor
MSM7730
13