EVAL-AD9837SDZ Analog Devices Inc, EVAL-AD9837SDZ Datasheet - Page 20

• Manufacturer Part Number: EVAL-AD9837SDZ
• Description: EVALUATION BOARD
• Manufacturer: Analog Devices Inc
• Series: -r

Specifications of EVAL-AD9837SDZ

• Main Purpose: Timing, Direct Digital Synthesis (DDS)
• Embedded: No
• Utilized Ic / Part: AD9837
• Primary Attributes: -
• Secondary Attributes: Graphical User Interface
• Kit Application Type: Clock & Timing
• Application Sub Type: Clock Generator
• Kit Contents: Software CD, USB Cable
• Silicon Manufacturer: Analog Devices
• Silicon Core Number: AD9837
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

AD9837
AD9837 to 80C51/80L51 Interface
Figure 26 shows the serial interface between the AD9837 and
the 80C51/80L51 microcontroller. The microcontroller is oper-
ated in Mode 0 so that TxD of the 80C51/80L51 drives SCLK of
the AD9837, and RxD drives the serial data line, SDATA. The
FSYNC signal is derived from a bit programmable pin on the
port (P3.3 is shown in Figure 26).
When data is to be transmitted to the AD9837, P3.3 is taken low.
The 80C51/80L51 transmits data in 8-bit bytes with only eight
falling SCLK edges occurring in each cycle. To load the remain-
ing eight bits to the AD9837, P3.3 is held low after the first eight
bits are transmitted, and a second write operation is initiated to
transmit the second byte of data. P3.3 is taken high following
the completion of the second write operation. SCLK should idle
high between the two write operations.
The 80C51/80L51 outputs the serial data in a format that has the
LSB first. The AD9837 accepts the MSB first (the four MSBs are
the control information, the next four bits are the address, and
the eight LSBs contain the data when writing to a destination
register). Therefore, the transmit routine of the 80C51/80L51
must take this into account and rearrange the bits so that the
MSB is output first.
80C51/80L51
Figure 26. 80C51/80L51 to AD9837 Interface
P3.3
RxD
TxD
FSYNC
SDATA
SCLK
AD9837
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AD9837 to DSP56002 Interface
Figure 27 shows the interface between the AD9837 and the
DSP56002. The DSP56002 is configured for normal mode asyn-
chronous operation with a gated internal clock (SYN = 0, GCK = 1,
SCKD = 1). The frame sync pin is generated internally (SC2 = 1),
the transfers are 16 bits wide (WL1 = 1, WL0 = 0), and the frame
sync signal frames the 16 bits (FSL = 0). The frame sync signal is
available on the SC2 pin, but it must be inverted before it is applied
to the AD9837. The interface to the DSP56000/DSP56001 is
similar to that of the DSP56002.
DSP56002
Figure 27. DSP56002 to AD9837 Interface
SCK
STD
SC2
FSYNC
SDATA
SCLK
AD9837