AnsweredAssumed Answered

Feeding DAC with my own Real Samples

Question asked by FArid on Dec 2, 2013
Latest reply on Jan 14, 2014 by ali786

Hi Dragos,

 

I'm using AD-FMCOMMS1 on ML605 carrier with no-OS reference design.

I noticed that you have replaced the dac_dma_data[] with sine_lut[] around a month ago. I can follow the codes and see the difference formally. However,I can not get what the conceptual difference is. What is the frequency of LUT(with which fs?)? How I1, Q1, I2, Q2 are going to be combined and feed the DAC IQ channels? Is there any block diagram showing this part of the system?

 

I want to send my own samples thru a similar LUT (bypass the DDS) while having the following criteria:

 

1) 2 Real Independent channels: I want to work with 2-independent real channels instead of IQ channels.

2) DAC input sampling rate (at LVDS): 491.52MSPS

3) DAC output sampling rate (at analog): 983.04MSPS --> hence I need to use DAC in X2 interpolation mode with HB1 as LPF(mode0) or HPF(mode3).

4) I want to set ADC sampling rate to 245.76MSPS.

 

In terms of software:

- Is it enough to change the sampling rates in main.c?

- How large can be my DAC LUT? Can I use the whole DDR3 RAM if I don't want to collect the Rx samples?

- Is there any extra condition I have to consider to have 2-independent channels?

- How can I set DAC Interpolation mode properly?

 

Bests,

FArid

Outcomes