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TS3USB221ERSER device detection issue

swapna bramandlapally1
Prodigy 170 points
Other Parts Discussed in Thread: TS3USB221



Hi all,

We are using two USB switch's TS3USB221ERSER in our design, One for input side Host port (Pendrive will attach here) and one more for device port(It will connect to PC).

Please see below for switch connection use case architecture.





We observed the following behaviors.

1) Both Mux/De-mux IC's are powered up and IC1,IC2 sel pins status is zero(0V): In this bypass mode, we should able to access direct pen drive content on device connector to attached PC.
    
Actual: We saw that "unknown device detected" message in PC.It is not detecting the pen drive content. I removed the pen drive and connected mouse.Mouse was working properly. I am able to see mouse movements also.

2) Both mux/demux IC's are powered up and IC1,IC2 sel pin of switch status is high(3.3V):In normal mode(processor will interact here), we are able to do detect the pen drive from host port through USB 1 Interface of the processor. But i am  not able to access the pendrive content on device port to attached PC."Unknown device
detected " message getting in device manger.I am getting the USB0 signals waveforms on IC2 mux/demux output also.


We tried below things:
1) we changed the Device port connector Type-A to TYPE-B.This time successfully accessing the pen drive in PC both the modes.USB TYPE-B connector is used for input side in  TS3USB221/A/E EVM also.What is the reason for this?
2) We have bypassed the IC2(Switch) and connected directly USB0 signals to Device port USB TYPE-A connector. We are successfully accessing the pen drive.


We preferred the first option.Now we are accessing the pen drive in both the modes. But, We are not understanding , Why USB mux/demux TS3USB221ERSER IC is expecting for USB Device connector Type-B or mini USB to access the USB device.

If we see electrical wise , both the connector signals are same. We are not using any USB ID pin signals.I am using VBUS, D-,D+ and Ground signals only. I just changed the USB Device connector, it starts working.



It would be great, if anyone can provide the quick help on this.

Thanks,

Regards
Swapna.B