i.MX Processors中的主题 imx25 OTG(device) ISOC multi-transaction issue

imx25 OTG(device) ISOC multi-transaction issue

tomfang — Mon, 10 Feb 2014 03:24:01 GMT

Hi guys:

I have a project using imx25 and a sensor to make a webcam,

using imx25 OTG device function to connect a host, video data transfered in ISOC endpoint,

software is your linux-2.6.31 SDK, now all functions are ok, but there is a problem:

if I configure this endpoint worked in "1 transaction", video data can be transfered, but the frame rate is only around 10,

for improving frame rate, I try to configure the endpoint worked in "3 transactions", but there isn't any data in USB line.

how can i do to make the "3 transactions" work?

I attached some pictures from USB analysis:

<<one transaction.PNG>>: configure imx25 ISOC endpoint worked in "1 transaction".

<<three transaction.PNG>>: configure imx25 ISOC endpoint worked in "3 transaction".

<<one transaction microsoft.PNG>>: microsoft webcam worked in "1 transaction".

<<isoc register>>: "1 transaction" and "3 transactions" configuration table from imx25 data sheet.

waiting for your response from heart.

jamesbone — Wed, 19 Feb 2014 17:54:21 GMT

We are doing some research with our team, to provide an answer.

karina_valencia — Tue, 04 Mar 2014 22:42:10 GMT

PeterChen Feb 25, 2014 7:25 PM (in response to Karina Valencia Aguilar)

What's the resolution for your camera? ususally, it is not reasonable you only get 10 frame/sec for 1 transaction.

If you want to support high bandiwdith for ISOC, please refer below patch: