Recently, I use a Xilinx FPGA(Spartan6-lx9tqg144) to control the ad9910. I let the AD9910 work in the DRG mode, and I got the DRG mode work, realizing the freqency sweep from 200MHz to 250MHz.
furthermore, I wanna to get the following waves, but I do not know how to make it.
Let Ti(i=1,2,3,4,5...) denote the time duration
T1 : 0-1us , AD9910 output a 200MHz sinusodial waveT2 : 1-10us, AD9910 output noneT3 : 10-11us, AD9910 output a 200MHz sinusodial waveT4 : 11-20us, AD9910 output noneT5 : 20-21us, AD9910 output a 202MHz sinusodial waveT6 : 21-30us, AD9910 output noneT7 : 30-31us, AD9910 output a 202MHz sinusodial waveT8 : 31-40us, AD9910 output none......The process may repeat from 200, 202, ... 249, to 250 MHz
(1) I found that, the maxium speed of the Serial Port of AD9910 is 70Mbps. that means, in 1us, 70bits are transmited at the most. If I use the ASF Register to control the Amplitude, I should send8+32 bits(Phase One 8bits, and Phase two 32bits) via the SPI protocolDoes it mean that it is hard for us to update the registers in 1us?
(2) If I use the parallel data mode, Can I make it?
(3)And I found that,If I use the ADI's AD8180(a multiplex chip, which has a 5ns channel switch time), Maybe I can control the output, but I am not so sure.
Because, I currently use the prototype board, I wanna to know How to use the AD9910 to Control the output amplitude?
Any advise are appreciated.Thank you
Thank you for your fast reply.
I write down the operations to see if I got your ideal
Step 1. Let the AD9910 Work in the DRG mode. Set the ASF Register to Ful Scale.
Step 2. Every 20us, I write to the Digital Ramp Limit Register(0x0B), to set the Upper Limit and The Lower Limit the same Frequency Word, e.g. 200MHz , 202MHz or the other number.
But the Digtal Ramp Limit Register is a 64 Bits Register. What you say is 32Bits. I guess Maybe it is wrong.
Maybe Let the AD9910 work in the Single Tone Mode. But When I refer to the AD9910's datasheet, I found that
in the Page 21, table 5 Data Source Priority. Only the RAM mode or DRG mode correspond to the OSK enabled conditon. And I get confused about it.