Serial Command - Novatech 425A Instruction Manual

Serial Command

F0 xxx.xxxxxxxxxxx
P0 N
E x
C x
R
CLR
A x
D0 N
PR x
S
QUE
M N
V0 N
I x
B aabb[cc[dd[ee[ff[gg[...]]]]]]]
NOVATECH INSTRUMENTS
Set Frequency of output in MHz to nearest 10 Hz. Decimal point
required.
Set relative Phase of output sinewave. N is an integer from 0 to 16383.
o
Phase is set to N*360 /16384 or N*2/16384 radians. This is useful
when multiple Model 425A are running from the same clock source.
Serial echo control. x=D for Echo Disable, x=E for Echo Enable. Dis-
able echo for maximum serial port speed.
Select clock source. x=E for External 250 MHz to 1000 MHz direct
input; x=R for 10.0 MHz Reference; x=I for Internal temperature com-
pensated reference. The quality of the external reference affects the
specifications of the 425A. The "F0" command requires scaling (see
manual) for clocks other than the internal oscillator.
Reset. This command resets the 425A. EEPROM data is preserved
and, if valid, is used upon restart. This is the same as cycling power.
Clear. This command clears the EEPROM valid flag and restores all
factory default values.
x=E for LVCMOS Enable, x=D for LVCMOS Disable. Default setting
is "D."
Set Divider value on LVCMOS output. N is an integer from 0 to
65535. The output frequency set by the "F0" command is divided by
N+1 before being sent to the LVCMOS driver.
x=E for Enable Prescaler, x=D for Disable Prescaler. When enabled,
the frequency set by the "F0" command is divided by 2 before enter-
ing the LVCMOS divider specified by the "D0" command. This
allows a maximum divide integer of 131072.
Saves current state into EEPROM and sets valid flag. The saved state
is used as the initial values upon next power up or reset. Use the
"CLR" command to return to default values.
Return present frequency, phase and status. Returns a character string
of all internal settings.
Mode command. Mode 'M
implemented at software Rev 1.5.)
Set Voltage level of output. In default, the amplitude is set to the
maximum of approximately 0.5 V
from 0 to 1023 (no decimal point allowed). Voltage level is scaled
(multiplied) by:
If N >1023, the command is ignored and the level remains at its
previous setting (approximately 0.14 V
Set the I/O update pulse method. If x=a, then an I/O update is issued
automatically at the end of each serial command (default). If x=m, then
a manual I/O update pulse is expected to be sent by a subsequent
'I p' command.
This Byte command allows each register in the DDS chip to be set.
Different registers require a various number of bytes to be written
depending upon the instruction word "aabb". Note that it is possible
to set the DDS chip into a non-functional mode, requiring a power
cycle to recover. All values are in hexadecimal and no error checking,
other than correct format, is performed.
4
Function
0' is single tone. (Only Mode 0 is
(+7 dBm) into 50  N can range
rms
0.27 + 0.19*N/264
to 0.50 V
rms rms
Rev 1.01, 425A Manual
).