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AD2 Data loss


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@attila

We are capturing LED data at rate of 20k(0.2 MBPS). some times when we connect ad2 to usb 2.0, we are observing data loss.

but when we connect ad2 to usb3.0, we didn't see any data loss.

any constraints are there from AD2 should connect to USB 3.0?

otherwise why are we observing data loss?

 

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Hi @RAJEEVA

Recording at this rate should't be an issue even with USB 1.1 (full-speed) or on a slow ARM SBC.

The AD2 has USB 2.0 controller, so there should be no difference when using USB 2.0 or 3.x host.

You may have other devices (system card reader, camera, ethernet...) connected to the same USB 2.0 root hub which highly reduce the rate or time to time block the respective USB channel.

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Hi @Wayne Chen

For higher sample rate I would no rely purely on the USB rate since the bulk transfer have no guaranteed bandwidth, so without suffice buffering it may lead to data loss.

The AD can use data compression in Logic Analyzer recording and the Protocol tool also uses compression.
With this you can capture high frequency bursts, which are typically used in communications.
With long busts (>16kb device buffer limit) or high average bit rates (>1Mbps usb transfer) the device buffer can overflow.

image.thumb.png.bb5cea19dd93beb8ca6ac6ffd28bc0dc.png

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Thank you Attila, Nice to have a solution to record I2S data streams with HD resolutions (for example, 96kHZ and 192kHz sample rates) to replace a bucky AP equipement for debugging. No I use an I2S DAC EVM as a workaround...Wayne Chen 06/20/2020

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