VDMA IP Vivado 2018.3 s2mm_frame_ptr_out KC705

[partieri]

I have a problem with VDMA 6.3 and KC705 evb.

I enable only write channel with 7 frame buffers, with genlock mode Master in the IP configuration GUI. I configured the VDMA with MicroBlaze in circular buffer Mode, enabled the s2mm interrupt but i see that frame numbers is greater than 7, and there is no circular buffer. The images below show the IP configuration GUI, and the ILA data. The same situation appears with the second VDMA enabled only read channel and configured in Slave mode, with mm2s_frame_ptr_out that is not circular and frame numbers is greater than 7.

What is the reason?

[florentw · Accepted solution]

Hi @partieri 

As per pg020 p43, the value outputted on mm2s_frame_ptr_out is encodded as gray code:

This is why you see number greater than 7 and not circular.

Check table c-1 in pg020.

What you se is correct:

9 (buffer 7) -> 1 (buffer 0) -> 3 (buffer 1) -> 2 (buffer 2) -> 6 (buffer 3) ...

Regards

[florentw]

HI @partieri 

Do you have any update on this? Is everything clear for you?

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