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Add custom transmit HDL block in AD-FMCOMMS2-EBZ HDL reference design

Question asked by kknd2009 on May 18, 2017
Latest reply on May 20, 2017 by kknd2009

Hi there, 


I know it's a quite frequently asked question. But my situation is slightly different. so I wanna make sure my idea about the implementation is correct. So if anyone could give me a comments, it would be very welcome.


I found that the block axi_ad9361_dac_dma is a fifo, which buffers the IQ data from the PS. The output IQ data will be available in fifo_rd_dout[63:0] once the fifo_rd_en is valid (I suppose it would be high voltage). The buffered IQ data will be read according to the fifo_rd_clk.


In the original design, this fifo_rd_clk comes from axi_ad9361 block, the frequency of which would be tx_samp_freq. Hence, the IQ data  will be transmitted in the tx_samp_freq rate. Under this assumption, if we change the fifo_rd_clk to a real low rate data clk  generated by the axi_ad9361 clk rather than the tx_samp_freq clk and add an additional HDL modulation block clocked by the tx_samp_freq between util_ad9361_dac_upack and axi_ad9361_dac_dma, the system design would not be modified significantly except the changes mentioned above.


1. Because the source code of axi_ad9361_dac_dma cannot be seen. Does anyone know how does fifo_rd_en perform? According to my understading, it probably performs as the normal fifo does.

2. When is  the output of fifo_rd_dout[63:0] available?(the next clock after fifo_rd_en is valid?)

3.Is there any other problem? in this implementation idea?   




I am a amateur in this part.