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TM4C1237E6PM: TivaWare USB not recognized, depending on the way I select pins in TI PinMux

Part Number: TM4C1237E6PM

I used TI PinMux to update the pinout for a device, along with the functions.  I took the generated code into CCS and compiled it into an image.  When I downloaded the image over USB DFU, the TIVA processor hung and I eventually saw a message from Windows saying "USB Device Not Recognized".  Looking at my board_init() function, I see that the PortFunctionInit() generated by PinMux is called right before the usb_dev_serial_init() function.  What change to a pin or function would lead to the loss of the USB interface?

  • I will need some clarification on your issue. Did you start with a blank TM4C1237E6PM on a custom board? Then you used the ROM based USB DFU bootloader to program your code into the device. After that, you no longer have USB connectivity. Is that correct?

    Once you program code into the device, the ROM bootloader is no longer called at startup unless the BOOTCFG register is modified. You would then be depending on your application code to properly use the USB port. Have you verified your application code for proper operation? Do you have JTAG pins on your board and a JTAG scan controller so you can debug your application code?