No output when XMOS used as listener

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cchandini
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Re: No output when XMOS used as listener

Postby cchandini » Thu Feb 23, 2017 12:26 pm

Will it pass data to media output FIFO even if the Timestamp Valid field is set to invalid? Would I be able to hear the audio output at XMOS end if without having timestamps?
Can you check for AVB 5.0 as well and let me know?
cchandini
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Postby cchandini » Thu Feb 23, 2017 12:29 pm

Will it pass data to media output FIFO even if the Timestamp Valid field is set to invalid? Would I be able to hear the audio output at XMOS end if without having timestamps?
Can you check for AVB 5.0 as well and let me know?
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larry
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Postby larry » Thu Feb 23, 2017 1:03 pm

It would be incorrect for the endpoint to use timestamps from packets where the valid flag is not set. I can't comment on version 5, but confident that version 6 and 7 will ignore timestamps with valid flag not set. Look for line that says

Code: Select all

if ((AVBTP_TV(pAVBHdr)==1))
cchandini
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Postby cchandini » Thu Feb 23, 2017 4:11 pm

Thanks a lot for your prompt reply! I'll check that up.
What I meant was my packets have Timestamp valid field set to "False" and the value of Timestamp field is always. So, in this will I be able to hear output at any one of the I2S channels or will these packets be dropped since there is no valid timestamp present?
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larry
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Postby larry » Thu Feb 23, 2017 4:19 pm

The 1722 listener is pushing data from all packets into the FIFO. Whenever there is a valid timestamp, the FIFO will pick it up and adjust the media clock. That is pretty much all the media output FIFO is there for.
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Postby cchandini » Thu Feb 23, 2017 4:25 pm

Sorry. A correction in the previous reply. What I meant was, my packets have Timestamp valid field set to "False" and the value of Timestamp field is always zero.
>> Whenever there is a valid timestamp, the FIFO will pick it up and adjust the media clock.
I wanted to know how would a listener behave if no timestamp is present? Can I conclude from your last reply that I will not be able to hear any audio output on I2S channel if timestamps are not present?
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larry
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Postby larry » Thu Feb 23, 2017 4:48 pm

I see. I think that media clock generation starts off with nominal 48kHz based on the endpoints xCORE reference clock. My guess is that it will all work and run at that rate until the FIFO underflows or overflows.
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Postby cchandini » Thu Mar 16, 2017 12:03 pm

Hi larry, would just connecting a XMOS AVB Endpoint to pc/host using xTAG-2 debug adapter lead to an automatic firmware update?
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Postby larry » Thu Mar 16, 2017 2:04 pm

No. Firmware upgrade happens is a protocol on top of 1772.1.
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Postby cchandini » Mon Mar 20, 2017 6:27 am

Okay...Currently, I don't have any sources/binaries for firmware v5.0. How can I debug my XMOS AVB endpoint? I have a xTAG-2 JTAG adapter as well.
From what I read online, if I use "xrun --xscope bin/app_avb_lc_demo.xe" , this will need app_avb_lc_demo.xe binary of v5.0 which I don't have. Is there any other method to debug the XMOS AVB Endpoint?

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