National ADC16DV160, Руководство пользователя

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SP16160CH1RB Reference Design Board User’s Guide
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8.0 Device Configuration
8.1 ADC16DV160 and LMH6517 Programming
The ADC16DV160 and LMH6517 are both
programmable via a shared serial programming
interface (SPI) bus that is accessible on the FutureBus
connector. Writing to a device is handled with individual
chip selects and is transparent to the user when using
the WaveVision 5 capture platform and software.
Registers are programmed via the Registers tab in the
WaveVision 5 software as shown in Figure 13 and
Figure 14. After the reference board is been identified
by the software, the Registers tab appears on the right-
hand side of the window. Opening the tab reveals
options for modifying the individual registers with high-
level nomenclature.
ADC Device Registers (Figure 13)
•
Operation Mode : Changes the operation of the
ADC from normal operation to sleep, power-
down, or fixed pattern modes.
•
Data Format : Selects the output data format as
Offset Binary or 2’s Complement.
•
Full Scale Reference Voltage : Varies the
reference range of the ADC from 2.4 Vpp to
1.0 Vpp.
•
Sample Phase : Selects the sampling edge of
the clock.
•
Clock Divider : Sets the internal clock to be
divided by 1 or 2.
•
Output Clock Phase : Varies the phase offset of
the output data clock.
LMH Device Registers (Figure 14)
•
Ch. A/B Enable: Enables or disables the DVGA
output stage.
•
DVGA A/B Attenuation (bits): Varies the
attenuation of the ladder attenuator from 0 dB
(value = 0) to 31.5 dB (value = 64).
The ADC16DV160 can only be programmed via SPI
but the LMH6517 can operate in multiple modes.
These modes include a Serial Mode in which the
device is programmed via SPI, Parallel Mode in which
the gain of the DVGA is controlled by manual switches,
and Pulse Mode. The SP16160CH1RB is factory
configured for Serial Mode but can be modified to
operate in Parallel Mode. Pulse Mode is not supported
on the SP16160CH1RB. Refer to the Optional
Configurations section for more information.
8.2 LMK04031B Programming
The LMK04031B, which provides the sample clock for
the ADC, must be configured correctly for the desired
clock frequency. Programming can be accomplished by
two methods.
The first method is to attach a small PIC-based module
that is included in this evaluation kit. This module is
plugged onto the 10-pin uWire header labeled “H3” as
described in section 5.3 of this user’s guide. If this
module is used, the JP1 jumper must be installed to
provide power from the main board to the PIC module.
The PIC module will program the LMK04031B to output
a 153.6 MHz single ended CMOS signal.
The second method for programming the LMK04031B
uses the 10-pin uWire header to connect the
LMK04031B’s serial programming interface (DATA,
CLK, LE) to a PC. To use this programming interface,
a special parallel port (LPT) cable supplied by National
Semiconductor allows the device to be directly
Figure 13: ADC16DV160 Registers tab in
the WaveVision 5 software (Default)
Figure 14: LMH6517 Registers tab in the
WaveVision 5 software
Max
Attenuation