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Posts: 4
Registered: ‎07-06-2017

CP2102 USB to UART Bridge problem with Android tablet

Hi !

 

I have a project which I thought it was finished last year. But lately, I discovered a problem with my CP2102 modules. 

 

My project is a hardware communicating with an Android Tablet over the CP2102 USB to Uart module with 115k Baudrate. In the tablet we have our application running.

Everything was finished, my Android developer and I tried the project many times. The communication was ok . 

 

But lately I found that the new CP2102 modules that I bought are not trancieving data after a start. Some modules are able to work fine , but some of them dont .

 

I thought the modules might be broken and then I tested them with my laptop and a small demo hardware over the Hyper terminal . With hyper terminal all the modules are able to work fine with my demo hardware  with 115k Baud

 

Any guys have any idea where might be the problem ? what might be the difference between new and old CP2102 modules ? 

 

Best Regards, 

 

Shalt

Posts: 328
Registered: ‎09-22-2009

Re: CP2102 USB to UART Bridge problem with Android tablet

When you refer to CP2102 modules, are you just talking about the bare chips, or are you buying these chips on our development kit boards? Can you describe your hardware setup in more detail?

Posts: 4
Registered: ‎07-06-2017

Re: CP2102 USB to UART Bridge problem with Android tablet

Dear Alan, 

 

thank you very much for your reply. 

 

I am not talking about the bare chip . I am using the modules that I bought from the Chinese market . You can see them at the photo.

 

We are using a rooting programme for android , KingoRoot . I couldnt figure out if the problem is with the driver of the chips? or the Kingo root has been modified and its been calling the drivers it self. 

 

only clue I got is the old modules are working but the new ones dont. But all of them can work with my computer+hardware . I tested all modules. 

CP2102 modules.jpg 

Posts: 4
Registered: ‎07-06-2017

Re: CP2102 USB to UART Bridge problem with Android tablet

Oh , and sorry, on my hardware , I connected this modules TX to my microcontrollers RX, and modules RX to my mc's TX . And usb part is connected to tabled by a usb to micro usb cable. 

Posts: 22
Registered: ‎03-29-2017

Re: CP2102 USB to UART Bridge problem with Android tablet

I had a problem with some modules with micro-USB connectors. Their 3.3V, DTR and TXD outputs were about 4.3V instead of 3.3V. That could cause a problem for 3.3V devices, but might work fine with 5V devices. So connect your new modules to USB and measure the voltage on those outputs. It turned out that the problem was caused by a trace on the module board connecting the /RST pin (pin 9) to USB V+. When I cut that trace and left /RST floating, it all worked fine.
Posts: 4
Registered: ‎07-06-2017

Re: CP2102 USB to UART Bridge problem with Android tablet

Dear Peabody , 

 

Thank you my friend . I will have a look to that . Its something I never checked before . I hope it works that way . I will share the result here . 

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Posts: 22
Registered: ‎03-29-2017

Re: CP2102 USB to UART Bridge problem with Android tablet

I should add that I found a source of good micro-USB modules at Ebay seller erizh-51. That was several months ago, but he probably has good stock left. I sent him a message explaining why he needed to maintain his current source for those parts. It appeared that the bad modules have silkscreen "TXO" for the TXD output, whereas the good ones show "TXD".