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We are trying to connect a CAN transceiver chip to the TM4C1290NCPDT MCU on the LAUNCHXL-CC2640R2 board. The first set of pins for CAN0 are used for serial communication with the CC2640R2 so the CAN1 pins must be used.
According to a note on page 1386 of the TM4C1290NCPDT data sheet, there is a USB mode in which pin 96 could be made available as GPIO.
The note says, “When used in OTG mode, USB0VBUS and USB0ID do not require any configuration as they are dedicated pins for the USB controller and directly connect to the USB connector's VBUS and ID signals. If the USB controller is used as either a dedicated Host or Device, the DEVMOD field in the USB General-Purpose Control and Status (USBGPCS) register can be used to connect the USB0VBUS and/or USB0ID inputs to fixed levels internally, freeing the PB0 and PB1 pins for GPIO use. Note that PB1 (USB0VBUS) is a 5-V tolerant signal as required. For proper self-powered Device operation, the VBUS value must still be monitored to assure that if the Host removes VBUS, the self-powered Device disables the D+/D- pull-up resistors. This function can be accomplished by connecting a standard GPIO to VBUS.
The termination resistors for the USB PHY have been added internally, and thus there is no need for external resistors. For a device, there is a 1.5 KOhm pull-up on the D+ and for a host there are 15 KOhm pull-downs on both D+ and D-.”
The latter part, monitoring the VBUS value, appears to be done by Pin 1 PD0/AIN15, using resistors R22 and R24 as a voltage divider.
What mode does the USB on the LAUNCHXL-CC2640R2 operate in?
