Configure Tiva C CAN

Hello, Dear. Support.

I programmed CAN interface with TivaWare 1.1 on TM4C1230C3PM.

I initialize and configured CAN to 500Kbps and communication test was successful.

however, It was not worked at 1Mbps.

The processor has running without errors, but CAN signal is not generated properly.

I can't find my fault, and I don't know what was wrong.

Here's my C code..

// PIOSC, 80MHz
ROM_SysCtlClockSet(SYSCTL_SYSDIV_2_5 | SYSCTL_USE_PLL | SYSCTL_OSC_INT |
SYSCTL_MAIN_OSC_DIS);

...

// CAN Init

ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE)
ROM_GPIOPinConfigure(GPIO_PE4_CAN0RX);
ROM_GPIOPinConfigure(GPIO_PE5_CAN0TX);
ROM_GPIOPinTypeCAN(GPIO_PORTE_BASE, GPIO_PIN_4 | GPIO_PIN_5);
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_CAN0);
ROM_CANInit(CAN0_BASE);
ROM_CANBitRateSet(CAN0_BASE, SysCtlClockGet(), 1000000); // It worked 500kbps with no problem
CANIntRegister(CAN0_BASE, CANIntHandler); 
ROM_CANIntEnable(CAN0_BASE, CAN_INT_MASTER | CAN_INT_ERROR | CAN_INT_STATUS); 
ROM_IntEnable(INT_CAN0); 
CANEnable(CAN0_BASE); 

...

There are something to do before call CANBitRateSet() ??

I tested same code to LM3S9B96 custom board with StellarisWare v9453, it also worked at 500kbps, not 1Mbps.

and I tied call CANBitTimingSet() instead of ROM_CANBitRateSet().

tCANBitClkParms tCANClkParams;

// bitrate = CAN Clock / ((ui32SyncPropPhase1Seg + ui32Phase2Seg + 1) * (ui32QuantumPrescaler))
// @80MHz, 500kbps = 4 / 3 / 0 / 20
tCANClkParams.ui32SyncPropPhase1Seg = 4;
tCANClkParams.ui32Phase2Seg = 3;
tCANClkParams.ui32SJW = 1;
tCANClkParams.ui32QuantumPrescaler = 20;
ROM_CANBitTimingSet(CAN0_BASE, &tCANClkParams);

however, did not work following code.

// @80MHz, 1000kbps = 4 / 3 / 0 / 10
tCANClkParams.ui32SyncPropPhase1Seg = 4;
tCANClkParams.ui32Phase2Seg = 3; 
tCANClkParams.ui32SJW = 1;
tCANClkParams.ui32QuantumPrescaler = 10;
ROM_CANBitTimingSet(CAN0_BASE, &tCANClkParams);

I changed clock to 6Mhz XTAL, or PLL, however It has same symptoms.

My targetboard communicated with the LAWICEL CANUSB device,

CANUSB  has been operated well 1Mbps with another microprocessor (Nuvoton NuMicro series)

I need your help.

Thanks.

Regards. Hyunkyo Oh.