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cy7c67200 transmission problem | Cypress Semiconductor

cy7c67200 transmission problem

Summary: 3 Replies, Latest post by Gayathri on 20 Sep 2012 05:25 AM PDT
Verified Answers: 0
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BSonel's picture
3 posts


I am using cy7c67200 as a full speed host controller to communiate with GSM modem.

Host is working in co-processor mode and communicating with master CPU via HPI. 

TD_ListDone Interrupt is used inform master CPU of transfer completion. 

Most of the time the transmission is fine, but several times a day master CPU informs, that transmission was lost. I took a closer look at this issue using oscilloscope. I revealed that the Host stops generating TD_ListDone interrupt (which isn't disabled in any way in program, also suspend mode is not used). When reading Endpoint Status Register after failure, there is only a NAK bit set (which is OK, beacuse most of the time modem doesn't have data to transfer).

My driver supports error recovery. but new transmission are initialised in TD_ListDone ISR, so when if it fails, whole transmission stops.  Communication is only using Bulk Endpoints and there are no transmission-free time intervals, it;s running all the time. 

Why the Host stops genrating these interrupts ? I cannot find a valid reason for this beahaviour, is it rather software (driver code, wrong host settings) or hardware problem (device hangs bus or sth.) ?



BSonel's picture
3 posts

 I am attaching some oscillograms, showing transmision being lost.

Channel 1 (Yellow) - HPI_INT line from EZ-OTG to main MCU,

Channel 4 (Green) - debug pin, set at the beggging of HPI_INT ISR, reset at the end,

M (Red) - differential USB bus signal.

BSonel's picture
3 posts

I have found a reason behind transmission being lost. The EZ-OTG on-chip processor is resetting itself, but I dont the cause.

Watchdog timer disabled, reset line decoupled. Is it possible, that electromagnetic radiation from GSM modem antenna disturbs EZ-OTG chip operation ? Modem is located rather close to usb chip on pcb.

gaya's picture
Cypress Employee
578 posts



Please create a tech support case at -> Support -> Technical Support -> Create a case. One of our engineers can assist you in this.




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