AD9835EB [ADI]
Evaluation Board for the AD9835 Direct Digital Synthesizer; 评估板用于AD9835直接数字频率合成器
| 型号： | AD9835EB |
| 厂家： | 
ADI |
| 描述： | Evaluation Board for the AD9835 Direct Digital Synthesizer |
| 文件： | 总8页 (文件大小：488K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Evaluation Board for the AD9835
Direct Digital Synthesizer
a
EVAL-AD9835EB
Components on the AD9835 Evaluation Board include a
50 MHz oscillator which provides the MCLK for the
AD9835. T he user can remove this oscillator, if required,
and drive the AD9835 with a different clock oscillator or
an external clock source via a BNC connector. A digital
buffer is also on the board so that the signals from the
edge connector are buffered.
FEATURES
Full-Featured Evaluation Board for the AD9835
Various Linking Options
PC Softw are for Control of AD9835
On-Board Patchw ork Area
I N T R O D U C T I O N
T his Application Note describes the evaluation board for
the AD9835 Direct Digital Synthesizer (DDS). T he
AD9835 is a numerically controlled oscillator employing
a phase accumulator, a sine look-up table and a 10-bit D/
A converter. T he part can be operated with clock
frequencies up to 50 MHz. Both phase modulation and
frequency modulation can be performed with the AD9835.
Full data on the AD9835 is available in the AD9835
datasheet available from Analog Devices and should be
consulted in conjunction with this Application Note when
using the evaluation board.
O P E RAT ING T H E AD 9835 E VALUAT IO N BO ARD
P ower Supplies
T his evaluation board has two analog power supply inputs:
AVDD and AGND. AVDD equals +5V or +3.3V and is used
to provide the AVDD for the AD9835. DGND and DVDD
connections are also available. T he DVDD is used to
provide the DVDD for the AD9835, the 50 MHz oscillator
and the DVDD for the digital buffer. DGND and AGND
are connected under the AD9835. T herefore, it is
recommended not to connect AGND and DGND
elsewhere in the system.
T he evaluation board interfaces to the parallel port of an
IBM compatible PC. Software is available with the
evaluation board which allows the user to easily program
the AD 9835.
All power supplies are decoupled to ground. AVDD and
DVDD are decoupled using 10µF tantalum capacitors and
0.1µF ceramic capacitors at the input to the evaluation
board. T he power supplies are again decoupled using
0.1µF capacitors at the AD9835, the crystal and the logic.
Figure 1: Evaluation Board Setup
IBM Compatible PC
Parallel Port Centronics
Printer Cable
AD9835.EXE
AD 9835
Evaluation Board
Inform ation furnished by Analog Devices is believed to be accurate
and reliable. However, no responsibility is assumed by Analog Devices
for its use; nor for any infringements of patents or other rights of third
parties which may result from its use. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices.
One TechnologyWay; P.O.BOX9106; Norwood, MA02062-9106 U.S.A.
Tel: 617/ 329-4700
Telex: 174059
Tw x: 710/ 394-6577
Cables: ANALOG NORWOOD MASS
Rev. A
EVAL-AD9835EB
LINK AND SWIT C H O P T IO NS
T here are four link options which must be set for the required operating setup before using the evaluation board. T he
functions of these link options are outlined below.
Lin k No.
F u n c t io n
When SELSRC = 0, the PSEL1 input can be controlled by the user via a SMB connector or alternatively,
LK 1
by switch SW1-2.
With LK1 in position "A", PSEL1 can be controlled from an external logic source through the SM B
connector, PSEL1.
With LK1 in position"B" PSEL1 is connected to SW1, allowing the user to control the PSEL1s i g n a l
using the double throw switch, SW1-2.
LK 2
LK 3
LK 4
When SELSRC = 0, the PSEL0 input can be controlled by the user via a SMB connector or
alternatively, by switch SW1-1.
With LK2 in position "A", PSEL0 can be controlled from an external logic source through the SM B
connector, PSEL0.
With LK2 in position"B" PSEL0 is connected to SW1, allowing the user to control the PSELOs i g n a l
using the double throw switch, SW1-1.
When SELSRC = 0, the FSELECT input can be controlled by the user via a SMB connector or alternatively,
by switch SW1-3.
With LK3 in position "A", FSELECT can be controlled from an external logic source through the SMB
connector, FSEL1.
With LK3 in position"B" FSELECT is connected to SW1, allowing the user to control the FSELECT signal
using the double throw switch, SW1-3.
T he reference to the AD9835 can be provided by the on-board reference, which is available at REFOUT ,
or an external reference of nominal value 1.21 V can be used. When LK4 is closed, the on-board reference
is used. When this link is opened, REFIN is disconnected from REFOUT and the reference must be provided
by the user via the SMB connector, REFIN1.
S E T - U P C O ND IT IO NS
Care should be taken before applying power and signals to the evaluation board to ensure that all link positions are as per the
required operating mode. T able 1 shows the position in which all the links are set when the evaluation board is packaged.
Table 1: Initial Link and Switch P ositions
Lin k No.
LK 1
P osit ion
F u n c t io n
B
LK1 is arranged so that PSEL1 is tied to SW1-2.
LK2 is arranged so that PSEL0 is tied to SW1-1.
LK3 is arranged so that FSELECT is tied to SW1-3.
REFOUT is tied to REFIN.
LK 2
B
LK 3
B
LK 4
I N
DVDD
S W 1
All the SW1 switches are arranged so that DVDD is selected.
Rev. A
- 2 -
EVAL-AD9835EB
E VALU AT IO N B O AR D INT E R F AC ING
Interfacing to the evaluation board is via a 36-way
centronics female connector, J1. T he pinout for the J1
connector is shown in Figure 2 and its pin designations are
given in T able 2.
S O C K E T S
T here are six sockets relevant to the operation of the AD9835
on this evaluation board. T he function of these sockets is
outlined in T able 3.
Table 3. Socket Functions
1
18
36
S o c ke t
RE F IN
I O U T
F u n c t io n
19
Sub-M iniature BN C Socket for REFIN .
Sub-M iniature BN C Socket for IOUT .
Figure 2: Pin Configuration for 36-Way Connector, J1.
M C L K
Sub-M iniature BN C Socket for the M C LK
input.
36- Way C on n ector P in D escr iption
F S E L
Sub-M iniature BN C Socket for FSELEC T .
Sub-M iniature BN C Socket for PSEL0.
Sub-M iniature BN C Socket for PSEL1.
D G N D
Digital Ground. T hese lines are connected to
the digital ground plane on the evaluation
board.
P SE L 0
P SE L 1
SD AT A
Serial Data. Data applied to this pin is buffered
before being applied to the AD9835. T he serial
data applied to the SDAT A pin is written to the
serial register of the device. T he data is then
transferred to the destination register, the control
register or the FSELECT /PSEL registers, the
control bits being used to identify the destination
for the data information. T he AD9835 accepts
C M OS logic levels.
C O N N E C T O R S
T here are three connectors on the AD9835 evaluation board
as outlined in T able 4.
Table 4. Connector Functions
C o n n e c t o r F u n ct ion s
SC L K
Serial Clock. T he signal on this pin is buffered
before being applied to the SCLK pin of the
AD 9835. T he AD 9835 requires an external
serial clock when data/control information is
being written to the device. T he serial clock
can be continuous or, it can idle high or low
between write operations.
J1
J2
36-Way Centronics Connector.
PCB Mounting T erminal Block. T he Digital
P ower Supply to the Evaluation Board is
provided via this Connector.
J3
PCB Mounting T erminal Block. T he Analog
P ower Supply to the Evaluation Board is
provided via this Connector.
F SYN C
T he signal on this pin is buffered before being
applied to the FSYNC pin of the AD9835. T he
FSYN C signal frames the 16-bit word being
loaded into the AD9835, the signal going low
for 16 SCLK cycles.
S W I T C H E S
T here is one switch on the AD9835 evaluation board. T his
switch is a double throw, end stackable switch. T his switch
can be used to control the FSELECT , PSEL0 and PSEL1
inputs.
Table 2. 36-Way Connector P in Funtions
MNEMO NIC
P IN NO .
2
SC L K
3
4
SD AT A
F SYN C
D G N D
19-30
Note: T he remainder of the pins on the 36-way connector are
no connects.
- 3 -
Rev. A
EVAL-AD9835EB
When the setup program is running the user will be prompted
to enter a destination directory for the software. A default
directory is given as C :\AD 9835. When the software is
installed a Windows Group called Analog D evices will be
created (Windows 3.1 only) and the AD9835 icon will be
placed there. D ouble clicking on this icon will run the
evaluation software. Windows 95 users can navigate through
the directories using Windows Explorer and then double
click on the AD9835.EXE file to start the software.
S O F T WAR E D E S C R IP T IO N
T he AD 9835 evaluatmon board comes with a floppy disk
containing software that allows the user to control the
AD9835 from an IBM compatible PC. T he PC is connected
to the evaluation board by a standard Centronics™ printer
cable.
Installingthe Software:
T he software will run on any IBM compatible PC which
meets the following requirements.
T h e E va lu a tion Softwa r e
• Microsoft Windows 3.1 or Windows95 installed.
• 80386 or higher processor.
When the program starts it will check the PC BIOS to detect
the address of the printer port installed. T here are three
possible base addresses at which a printer port can reside and
these are shown below together with the printer names.
• At least 1.5 Mb of free hardisk space.
T he software is distributed on a single 3.5 inch diskette. T he
diskette contains all the files required to install and run the
software.
PrinterBase Address (hex)
LP T 1
LP T 2
P RN 1
0x378
0x278
0x3BC
Using either the Program Manager or the File Manager the
user should select the floppy drive ( usually a:) and double
click on the SET UP.EXE file. T his program simplifies the
installation of the software by copying the files from the
diskette to the relevant directories on the hard disk.
If there is more than one printer port installed the software
will chose the first one it finds. It is possible to change the
printer port from the software by clicking the Select Port
button. T he main screen for the evaluaton board software is
shown in Fig. 3 below.
Figure 3: The Main Screen
Rev. A
- 4 -
EVAL-AD9835EB
The SE LSRC Bit
Featur es of the AD 9835 E valuation Boar d Softwar e
T he SELSRC bit of the AD 9835 is used to control the
selection of the frequency and phase registers used to provide
the output. If this bit is a zero the frequency and phase
selection comes from FSELECT , PSEL0 and PSEL1 pins
respectively. If the bit is a 1 then the registers are selected by
software. Pressing the SELSRC button toggles this bit on the
AD9835 and also enables or disables changing the frequency
and phase registers from software as required.
T he software allows the user to control all the functionality of
the AD9835. T he main features are listed below.
• Access to both Frequency 0 and Frequency 1 registers
• Access to the Phase Reg. 0, Phase Reg. 1, Phase Reg. 2 and
Phase Reg. 3
• Access to Sleep, Reset and SELSRC bits.
• Ability to sweep through a frequency range using either the
Frequency 0 or Frequency 1 registers.
It should be noted that since there is no readback facility on
the AD9835 it is not possible to determine the contents of any
register which has not been programmed by the software. For
this reason selecting a frequency or phase register which
hasn't been programmed may give an unpredicted output.
Each of these features is described in detail in this application
note.
T he F r equency Register s
The Sweep Facility
T he AD 9835 contains 2 frequency registers which can be
programmed individually. T he software allows the user to
enter any frequency value between 0Hz and half the master
clock frequency. If a value outside this range is entered the
software picks the closest valid value. T he frequency value is
converted to a 32 bit hexidecimal number which is loaded to
the appropriate frequency register when the enter key is
pressed. T he hexidecimal number is also displayed on the
main screen.
Pressing the Sweep button displays a new screen which can be
used to program the AD 9835 to produce a continuously
increasing or decreasing frequency sweep. T he user has the
option of entering a start frequency, a stop frequency and a
step frequency. T here is also the option of setting the delay
between steps and the number of time the sweep is to be
repeated. If the user were to enter the sweep values shown
below then the frequency outputs also shown below will be
generated. Note that if the frequency span is not an integer
multiple of the step frequency then the span from the second
last frequency to the last frequency will be such that the stop
frequency is the last frequency outputed to the AD9835.
The P hase Register s
T he AD 9835 contains four phase register which can be
individually loaded with different values. T he phase numbers
are entered as integer values between 0 and 4095 (corresponding
to 0° to 360° phase shift). Once again the values are loaded
to the appropriate phase register when the enter key is
pressed.
Star t Fr eq.
Stop Fr eq.
Step Fr eq.
1.00000M H z
1.70000M H z
0.20000M H
Frequency Outputs:
1.00000M H z
1.20000M H z
1.40000M H z
1.60000M H z
1.70000M H z
Nor m a l/Sleep M od e
T he Control Register of the AD9835 contains a sleep bit to
put the part into a power-down mode. When this bit is a logic
1 the internal clocks are disabled and the D AC's current
sources and REF O U T are turned off. T his bit can be
controlled by the two radio buttons in the N ormal/Sleep
Mode box. T he software defaults to Normal Mode reflecting
the reset state of the AD9835.
Both Frequency Register 0 and Frequency Register 1 can be
loaded with seperate frequency, step, delay and loop
information but the output from the AD9835 will depend on
which frequency register is selected via the FSELECT pin.
If changing the frequency register is required then the user
should ensure that the SELSRC bit is zero before starting the
sweep.
Reset Mode
T he Reset bit in the C ontrol Register of the AD 9835 is
controllable by the RESET button of the AD9835 Evaluation
Board Software. Pressing this button toggles the state of the
bit in the control register. Note that it is assummed that the
RESET bit is low when the software is started. Setting the
RESET bit to 1 will set the phase accumulator to zero phase
corresponding to a full scale output.
Ad d ition a l In for m a tion
Information about the current version of software can be
gathered from the About Screen (accessed by pressing the
About button on the main screen).
- 5 -
Rev. A
Figure 4: Eval-AD9835EB Schematic
EVAL-AD9835EB
Table 5. Com ponent Listing
Description
Item Qty
Reference
U 1
Supplier / No.
1
1
1
1
1
7
1
2
3
1
1
1
6
1
3
1
4
1
1
1
4
AD 9835
AD I AD 9835
FEC 382-267
FEC 422-708
FEC 571-842
FEC 146-227
FEC 146-224
FEC 643-683
FEC 543-627
FEC 543-070
FEC 543-524
FEC 543-251
FEC 299-844
FEC 147-753
FEC 528-432
FEC 528-432
FEC 150-410
FEC 738-554
FEC 738-529
FEC 151-789
FEC 148-922
2
U 2
74H C T 244
3
S W 1
Double throw end stackable switch
50M H Z C M OS/T T L C rystal
100nF Ceramic Capacitor
10nF ceramic Capacitor
10uF T antalum Capacitor
10KW Resistor
4
XT AL1
5
C1 C2 C4 C5 C6 C7 C9
6
C 3
7
C8 C10
8
R1 R2 R3
9
R4
51KW Resistor
10
11
12
13
14
15
16
17
18
19
20
R5
3.9KW Resistor
R6
300W Resistor
PSEL1PSEL0FSELCLKIOUT REFIN
Sub Miniature BNC connector
36 Way Centronics Connector
3 pin sil header
J1
Lk1 Lk2 Lk3
L k4
2 pin sil header
Lk1 Lk2 Lk3 Lk4
jumper
U 2
20 pin dil solder socket
14 pin dil solder socket
T wo Way T erminal Block
Each corner
XT AL1
J2 J3
Rubber-Stick-On feet
Figure 5. Eval-AD9835EB Silkscreen Artwork
- 7 -
Rev. A
EVAL-AD9835EB
Figure 6. Eval-AD9835EB Component Side Artwork
Figure 7. Eval-AD9835EB Solder Side Artwork
Rev. A
- 8 -
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