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