Please let me know the USB Serial part you are using?
I am using CY7C65211-24LTXI which is a part of
(schematics http://www.cypress.com/file/443806/download )
I had a similar problem with the CY7C65215. Took forever to debug with Cypress support, but the problem finally turned out to be a bug in the firmware in the part:
Cypress External Response:201/18/2017 5:31 AM - Hemanth R
Hello Jay, Apologies for the delay caused. I was unable to work on this case. The application which I have sent you was tested with Firmware version 184.108.40.206 Today I have tried with firmware version 220.127.116.11 and I am able to reproduce the issue. I found similar issue as seen in your case i.e 18.104.22.168 I will get back to you with the solution. Can you provide your Contact info so that I could have a call if required. Thanks and Regards, Hemanth
They ended up sending me new firmware for the 7C65215 and I needed to re-program my part using a MiniProg3 (ironically the part can't be re-programmed over USB). Once I did this the problem went away.
Unfortunately this took over a month to work out with Cypress support. Good luck.
Is CY7C65211A present on any of the development boards?
The CY7C65211A part is pin to pin compatible with the CY7C65211 part and can be used with the CYUSB234 DVK.
So, no support about this issue for part that is still in active production?
Please put this issue in errata sheet, if it is a matter of loaded FW.
Is is then possible to explain how same hardware instance of cy7c65211 exhibits different responses when using different client side (PC) software libraries ?
Best regards, Ziga
A lot of discussion was internal, and won't post it here. Mainly they agreed to change FW and send it for a test. Now they are steering me in direction of part *A. BUT why when cy7c65211 is still in production, and errata does not say anything about this.
As discussed internally, it is suitable to use the CY7C65211A part for your application which has the fix in the firmware for the issue and we will be updating the errata in the datasheet soon.