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by sargsyanga
Tue Jun 23, 2020 12:52 am
Forum: Compute Module
Topic: Missing USB 2.0 Isochronous Transfers
Replies: 8
Views: 817

Re: Missing USB 2.0 Isochronous Transfers

Hi, After doing some more experimenting with the on-board devices , it turned out the issue is caused by NL-SW-LTE-TSVG-B LTE modem. In particular the "option" and "cdc-wdm" drivers are scheduling a lot of URBs making RPI incapable of handling Isochronous IN transfers on time. Did anybody experience...
by sargsyanga
Sun Jun 21, 2020 4:31 pm
Forum: Compute Module
Topic: Missing USB 2.0 Isochronous Transfers
Replies: 8
Views: 817

Re: Missing USB 2.0 Isochronous Transfers

Thanks! I will give it a shot. That's actually a good idea to do the compression on MCU. I am currently sending the data in PCM format and doing FLAC compression on audio data on the RPI, however if I am going to use raw Bulk pipe instead of the audio interface I can run compression on the MCU first...
by sargsyanga
Sat Jun 20, 2020 10:03 pm
Forum: Compute Module
Topic: Missing USB 2.0 Isochronous Transfers
Replies: 8
Views: 817

Re: Missing USB 2.0 Isochronous Transfers

One of the reasons I was trying to go with Isochronous transfer approach is that I am limited to 128K RAM which allows to hold up to 64ms of data. I guess I'll have to respin the board and add SDRAM to be able to use larger buffers. Do you think having an SDRAM which is able to store up to 8 seconds...
by sargsyanga
Sat Jun 20, 2020 6:38 pm
Forum: Compute Module
Topic: Missing USB 2.0 Isochronous Transfers
Replies: 8
Views: 817

Re: Missing USB 2.0 Isochronous Transfers

In my system the USB interface is used for sampling data as well as writing it back to the drive. The reason Isochronous transfer was selected was to avoid sharing the bandwidth with other bulk pipes since I cannot guarantee that under heavy load the DAQ will be serviced on time. Can you please comm...
by sargsyanga
Sat Jun 20, 2020 2:11 am
Forum: Compute Module
Topic: Missing USB 2.0 Isochronous Transfers
Replies: 8
Views: 817

Re: Missing USB 2.0 Isochronous Transfers

Hi, After looking more into this issue, I am observing following messages in the kernel log when the issue occurs [ 3695.888803] retire_capture_urb: 5 callbacks suppressed [ 3701.274773] retire_capture_urb: 7 callbacks suppressed [ 3706.969307] retire_capture_urb: 7 callbacks suppressed [ 3712.00752...
by sargsyanga
Wed Jun 17, 2020 5:49 pm
Forum: Compute Module
Topic: USB 2.0 Dropped frames
Replies: 26
Views: 6313

Re: USB 2.0 Dropped frames

Hi.

I am experiencing similar problem with Isochronous transfers. Was there a solution to this problem? If yes, can you please share the code so I can try the fix on my end?

Thank you
by sargsyanga
Wed Jun 17, 2020 4:11 am
Forum: Compute Module
Topic: Missing USB 2.0 Isochronous Transfers
Replies: 8
Views: 817

Missing USB 2.0 Isochronous Transfers

Hi, We are using CM3+ to build a Data Acquisition System with 4.19.71-rt24-v7+ Real-time Kernel. The DAQ devices are connected to the CM3+ over USB 2.0 bus. There is also an M.2 SATA drive connected to USB bus (over USB to SATA controller). The basic application flow is to record the ADC data sample...

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