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Not able to generate frequency sweep programming the EVAL-AD9914 board with an Arduino

Question asked by GerardD on Jun 11, 2018
Latest reply on Jun 22, 2018 by GerardD

Hello,

 

I am controlling the AD9914 evaluation board with an Arduino using SPI to perform a linear sweep. To this purpose, jumpers P203, P204 and P205 have been disabled. The REF_CLK is 25 MHz and N is set to 100 to obtain a system clock of 2.5 GHz. I would like to generate the frequency sweep from 855 MHz to 865 MHz with freq. steps of 100 Hz and a rate of 10 ns. When using the eval board software everything works fine, but when trying to control the eval board with the Arduino I obtain a single tone at 855 MHz (without performing the sweep). Both no-dwell bits are set to 1.

Here is my register configuration:

CFR1=0x0100C000
CFR2=0x000E2000
CFR3=0x0004321C
CFR4=0x01052120
Digital Ramp Lower Limit=0x578D4FDF (register address is 0x04,855MHz)
Digital Ramp Upper Limit=0x589374BC (register address is 0x05,865MHz)
Rising Digital Ramp stope=0x000000AB (register address is 0x06,100 Hz)
Falling Digital Ramp stope=0x000000AB (register address is 0x07,100 Hz)
Digital Ramp Rate Register=0x00010001 (register address is 0x08,0.01us)

 

With this pin configuration I obtain a constant tone at 855 MHz (see attached figure) and no DROVER. I have performed several tests, but I am not able to obtain the frequency sweep. Should I consider disabling another jumper in the evaluation board? Any suggestions of what I am doing wrong? Thank you in advance.

 

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