Texas Instruments Tiva TM4C123GH6PM, User Manual

Page: 62 / 352

Controller Area Network (CAN)
Description:
Returns the value of one of two interrupt status registers. The interrupt status register read is
determined by the
eIntStsReg parameter, which can have one of the following values:
CAN_INT_STS_CAUSE - indicates the cause of the interrupt
CAN_INT_STS_OBJECT
- indicates pending interrupts of all message objects
CAN_INT_STS_CAUSE returns the value of the controller interrupt register and indicates the
cause of the interrupt. It is a value of
CAN_INT_INTID_STATUS
if the cause is a status inter-
rupt. In this case, the status register should be read with the ROM_CANStatusGet() function.
Calling this function to read the status will also clear the status interrupt. If the value of the inter-
rupt register is in the range 1-32, then this indicates the number of the highest priority message
object that has an interrupt pending. The message object interrupt can be cleared by using
the
ROM_CANIntClear() function, or by reading the message using ROM_CANMessageGet()
in the case of a received message. The interrupt handler can read the interrupt status again to
make sure all pending interrupts are cleared before returning from the interrupt.
CAN_INT_STS_OBJECT returns a bit mask indicating which message objects have pending
interrupts. This can be used to discover all of the pending interrupts at once, as opposed to
repeatedly reading the interrupt register by using
CAN_INT_STS_CAUSE .
Returns:
Returns the value of one of the interrupt status registers.
6.2.1.12 ROM_CANMessageClear
Clears a message object so that it is no longer used.
Prototype:
void
ROM_CANMessageClear(uint32_t ui32Base,
uint32_t ui32ObjID)
ROM Location:
ROM_APITABLE
is an array of pointers located at
0x0100.0010
.
ROM_CANTABLE
is an array of pointers located at
ROM_APITABLE[18]
.
ROM_CANMessageClear
is a function pointer located at
ROM_CANTABLE[9]
.
Parameters:
ui32Base is the base address of the CAN controller.
ui32ObjID is the message object number to disable (1-32).
Description:
This function frees the specified message object from use. Once a message object has been
“cleared,” it will no longer automatically send or receive messages, or generate interrupts.
Returns:
None.
6.2.1.13 ROM_CANMessageGet
Reads a CAN message from one of the message object buffers.
62 April 8, 2013