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AD9910 basic configuration

Question asked by liborek84 on Aug 12, 2014
Latest reply on Aug 13, 2014 by LouijieC

Hi all,


I want to help with a basic configuration of AD9910. I inherited a board with this chip after colleague who left our company.

The last three days I try to configure the AD9910 into a single tone mode...


The AD9910 on my board is clocked from a 25 MHz crystal oscillator. All his three profile select inputs are grounded (profile 0 selected) and SPI bus uses two separate data wires (SDI and SDO).


My configuration sequence is as follows. At first I reset the chip with impulse on a MASTER_RESET signal. Then I write the configuration registers and at the end I generate impulse on IO_UPDATE input.

When I try to read back all registers which I previously written down then I get the same values which I wrote there.


After this configuration sequence the AD9910 enables his PLL a generates internal system clock which is equal to 500 MHz. I am sure because I can measure the clock signal with frequency of 1/4 of internal system clock on pin SYNC_CLK (125 MHz).


Throught it all I am not able to generate required output sine signal.


I think that there in my configuration is some stupid mistake, but I can't to find it. I will be glad for any advice.







My configuration is:

CFR1 (0x00) = 0x00410002

Inverse sinc filter enable, sine output, SDIO is input only


CFR2 (0x01) = 0x01400020

Enable amplitude scale form single tone profiles, SYNC_CLK enable, disable sync timing validation


CFR3 (0x02) = 0x11100128

select VCO1, 262 uA, enable PLL, N = 20


Auxiliary DAC Control (0x03) = 0x0000007F

CODE = 127


Profile 0 (0x0E) = 0x3FFF00002C8B4395

FTW = 0x2C8B4395 -> fout = 87 MHz

ASF = 0x3FFF -> Maximum amplitude