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Adventurer
Adventurer
1,767 Views
Registered: ‎07-09-2017

axi_ama tlast port issue

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Hi everyone,

 

here I have a hls IP using axis interface without tlast port, and I was trying to connect it with PS with AXI Direct Memory Access with the help of AXI4-stream Subset Converter. 

 

How should I deal with the tlast port here? 

 

Regards

 

snip_20170929155812.png

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Voyager
Voyager
2,423 Views
Registered: ‎06-24-2013

Hey @jianmingli1,

 

How should I deal with the tlast port here?

You can enable TLAST for the Master Interface on the Subset Converter and set a Generate TLAST interval (e.g. 256) so that TLAST will be set every n-th transaction. Tying TLAST to '1' might be an option too, but setting it to '0' is not a good solution because it will cause problems with DMA.

 

Hope this helps,

Herbert

-------------- Yes, I do this for fun!

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Voyager
Voyager
2,424 Views
Registered: ‎06-24-2013

Hey @jianmingli1,

 

How should I deal with the tlast port here?

You can enable TLAST for the Master Interface on the Subset Converter and set a Generate TLAST interval (e.g. 256) so that TLAST will be set every n-th transaction. Tying TLAST to '1' might be an option too, but setting it to '0' is not a good solution because it will cause problems with DMA.

 

Hope this helps,

Herbert

-------------- Yes, I do this for fun!

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Adventurer
Adventurer
1,738 Views
Registered: ‎07-09-2017

@hpoetzl

 

Hi Herbert,

 

may I ask one more question? 

I have an IP with two inputs (real and imag) and one output. How can I connect them to an AXI Direct Memory Access?

 

Regards

 

snip_20170929180444.png

 

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Voyager
Voyager
1,723 Views
Registered: ‎06-24-2013

Hey @jianmingli1,

 

You can use the AXI Stream Broadcaster IP for this.

The slave interface needs to be twice as wide as the two master interfaces and you need to select the appropriate range under 'Stream Splitting Options'.

 

Best,

Herbert

-------------- Yes, I do this for fun!
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Adventurer
Adventurer
1,714 Views
Registered: ‎07-09-2017

@hpoetzl

 

Hi Herbert,

 

I tried your advice. But it's like that master interface width is twice as wide as the slave interface by default. is that right?

 

Regards

snip_20170929195403.png

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Voyager
Voyager
1,701 Views
Registered: ‎06-24-2013

Hey @jianmingli1,

 

But it's like that master interface width is twice as wide as the slave interface by default.

It seems that this is one of the IP issues which never got fixed ...

 

Basically you could just drop the Boardcaster IP and split up the stream manually for read and imaginary parts, but from your picture I see another problem. Your stream is only 16bit wide and you want to supply two 16bit ports (real and imag) with data, so your options there are ...

  • Alternate between real and imaginary values (requires some HDL)
  • Increase the width of your source to 32bit and split it up into two 16bit parts

Note that in any case you need to handle the TREADY and TVALID properly, which is not that complicated.

 

Best,

Herbert

-------------- Yes, I do this for fun!