EK-TM4C1294XL: CAN communication using EK-TM4C1294XL as the master and EK-TM4C123GXL

Hi Conor,

  You cannot just run the simple_can_rx as is on the EK-TM4C123GXL board because the system clock setup and CAN bit rate setup is different between TM4C129 and TM4C123. Refer to the C:\ti\TivaWare_C_Series-2.2.0.295\examples\peripherals\can\simple_rx.c example for details. As you can see in below highlighted lines where there is a difference on the clock and bit rate setup. You must change accordingly for running the code on EK-TM4C129GXL. 

//*****************************************************************************
//
// Configure the CAN and enter a loop to receive CAN messages.
//
//*****************************************************************************
int
main(void)
{
#if defined(TARGET_IS_TM4C129_RA0) || \
defined(TARGET_IS_TM4C129_RA1) || \
defined(TARGET_IS_TM4C129_RA2)
uint32_t ui32SysClock;
#endif

tCANMsgObject sCANMessage;
uint8_t pui8MsgData[8];

//
// Set the clocking to run directly from the external crystal/oscillator.
// TODO: The SYSCTL_XTAL_ value must be changed to match the value of the
// crystal used on your board.
//
#if defined(TARGET_IS_TM4C129_RA0) || \
defined(TARGET_IS_TM4C129_RA1) || \
defined(TARGET_IS_TM4C129_RA2)
ui32SysClock = SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ |
SYSCTL_OSC_MAIN |
SYSCTL_USE_OSC)
25000000);
#else
SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
SYSCTL_XTAL_16MHZ);
#endif

//
// Set up the serial console to use for displaying messages. This is
// just for this example program and is not needed for CAN operation.
//
InitConsole();

//
// For this example CAN0 is used with RX and TX pins on port B4 and B5.
// The actual port and pins used may be different on your part, consult
// the data sheet for more information.
// GPIO port B needs to be enabled so these pins can be used.
// TODO: change this to whichever GPIO port you are using
//
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);

//
// Configure the GPIO pin muxing to select CAN0 functions for these pins.
// This step selects which alternate function is available for these pins.
// This is necessary if your part supports GPIO pin function muxing.
// Consult the data sheet to see which functions are allocated per pin.
// TODO: change this to select the port/pin you are using
//
GPIOPinConfigure(GPIO_PB4_CAN0RX);
GPIOPinConfigure(GPIO_PB5_CAN0TX);

//
// Enable the alternate function on the GPIO pins. The above step selects
// which alternate function is available. This step actually enables the
// alternate function instead of GPIO for these pins.
// TODO: change this to match the port/pin you are using
//
GPIOPinTypeCAN(GPIO_PORTB_BASE, GPIO_PIN_4 | GPIO_PIN_5);

//
// The GPIO port and pins have been set up for CAN. The CAN peripheral
// must be enabled.
//
SysCtlPeripheralEnable(SYSCTL_PERIPH_CAN0);

//
// Initialize the CAN controller
//
CANInit(CAN0_BASE);

//
// Set up the bit rate for the CAN bus. This function sets up the CAN
// bus timing for a nominal configuration. You can achieve more control
// over the CAN bus timing by using the function CANBitTimingSet() instead
// of this one, if needed.
// In this example, the CAN bus is set to 500 kHz. In the function below,
// the call to SysCtlClockGet() or ui32SysClock is used to determine the
// clock rate that is used for clocking the CAN peripheral. This can be
// replaced with a fixed value if you know the value of the system clock,
// saving the extra function call. For some parts, the CAN peripheral is
// clocked by a fixed 8 MHz regardless of the system clock in which case
// the call to SysCtlClockGet() or ui32SysClock should be replaced with
// 8000000. Consult the data sheet for more information about CAN
// peripheral clocking.
//
#if defined(TARGET_IS_TM4C129_RA0) || \
defined(TARGET_IS_TM4C129_RA1) || \
defined(TARGET_IS_TM4C129_RA2)
CANBitRateSet(CAN0_BASE, ui32SysClock, 500000);
#else
CANBitRateSet(CAN0_BASE, SysCtlClockGet(), 500000);
#endif

//
// Enable interrupts on the CAN peripheral. This example uses static
// allocation of interrupt handlers which means the name of the handler
// is in the vector table of startup code. If you want to use dynamic
// allocation of the vector table, then you must also call CANIntRegister()
// here.
//
// CANIntRegister(CAN0_BASE, CANIntHandler); // if using dynamic vectors
//
CANIntEnable(CAN0_BASE, CAN_INT_MASTER | CAN_INT_ERROR | CAN_INT_STATUS);

//
// Enable the CAN interrupt on the processor (NVIC).
//
IntEnable(INT_CAN0);

//
// Enable the CAN for operation.
//
CANEnable(CAN0_BASE);

//
// Initialize a message object to be used for receiving CAN messages with
// any CAN ID. In order to receive any CAN ID, the ID and mask must both
// be set to 0, and the ID filter enabled.
//
sCANMessage.ui32MsgID = 0;
sCANMessage.ui32MsgIDMask = 0;
sCANMessage.ui32Flags = MSG_OBJ_RX_INT_ENABLE | MSG_OBJ_USE_ID_FILTER;
sCANMessage.ui32MsgLen = 8;

//
// Now load the message object into the CAN peripheral. Once loaded the
// CAN will receive any message on the bus, and an interrupt will occur.
// Use message object 1 for receiving messages (this is not the same as
// the CAN ID which can be any value in this example).
//
CANMessageSet(CAN0_BASE, 1, &sCANMessage, MSG_OBJ_TYPE_RX);