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USB Interface doesn't work after a power cycle

Thomas Rapolder
Prodigy 110 points
Other Parts Discussed in Thread: TM4C1233H6PZ

I'm working with a TM4C1233H6PZ on a custom board. My debugging environment consists of CCS 5.4 and a XDS200 interface. 

I'm investigating on following issue: I have a sample code, overall the usb_dev_serial of tivaware_C_Series 1.1, which emulates a CDC device. If I'm running my code on a "blank" device within the debugging environment the PC side enumerates and I'm getting a new virtual COM port at the PC side. Also a terminal emulation is working without any problems. After a power cycle I run the code equally in my debugging environment, but the PC enumerates not any more. The cpu is till running. I can observe this by a software controlled blinking LED. Only a flash erase in CCS gets the device back to enumerate on the next run until the next power cycle ...

Another miracle behaviour to me, which is obviously in correlation with the first issue, is the fact that the blank device only enumerates as a DFU device, if the XDS200 debugger is plugged, also the CCS is not running. If I cut the XDS 200 connection the Stellaris Device Firmware Update disappears out of the device manager.

Are there any hints to troubleshooting this issue? Which influence has the XDS200 on the device?

Best regards

Thomas Rapolder 

  • 0
    Prodigy 110 points

    Meanwhile i did some more investigations in this topic and added some configuration code:

    ROM_GPIOPinTypeUSBAnalog(GPIO_PORTJ_BASE, GPIO_PIN_1 | GPIO_PIN_0);
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_USB0);
    ROM_SysCtlPeripheralReset(SYSCTL_PERIPH_USB0);
    ROM_SysCtlUSBPLLEnable();

    And I get a more deterministic behaviour. Now the CDC or DFU device only enumerates only if the XDS 200 is plugged also after a power cycle. But without the XDS 200 the USB (physical) interface isn't in operation. So the XDS 200 has definitly an influence on the startup of the processor. What are the default levels of the boundary scan interface. Any hints on degugging this issue.

    Best regards

    Thomas Rapolder    

     

  • 0 in reply to Thomas Rapolder
    Prodigy 110 points

    Hello,

    no further investigations on this topic necessary!