Controller Area Network (CAN)
Parameters:
ui32Base is the base address of the CAN controller.
psClkParms points to the structure with the clock parameters.
Description:
Configures the various timing parameters for the CAN bus bit timing: Propagation segment,
Phase Buffer 1 segment, Phase Buffer 2 segment, and the Synchronization Jump Width.
The values for Propagation and Phase Buffer 1 segments are derived from the combination
psClkParms->ui32SyncPropPhase1Seg parameter. Phase Buffer 2 is determined from the
psClkParms->ui32Phase2Seg parameter. These two parameters, along with psClkParms-
>ui32SJW are based in units of bit time quanta. The actual quantum time is determined by
the psClkParms->ui32QuantumPrescaler value, which specifies the divisor for the CAN mod-
ule clock.
The total bit time, in quanta, is the sum of the two Seg parameters, as follows:
bit_time_q = ui32SyncPropPhase1Seg + ui32Phase2Seg + 1
Note that the Sync_Seg is always one quantum in duration, and is added to derive the correct
duration of Prop_Seg and Phase1_Seg.
The equation to determine the actual bit rate is as follows:
CAN Clock / ((ui32SyncPropPhase1Seg + ui32Phase2Seg + 1) ∗ (ui32QuantumPrescaler ))
This means that with ui32SyncPropPhase1Seg = 4, ui32Phase2Seg = 1,
ui32QuantumPrescaler = 2 and an 8 MHz CAN clock, that the bit rate is (8 MHz) / ((5
+ 2 + 1) ∗ 2) or 500 Kbit/sec.
Returns:
None.
6.2.1.4 ROM_CANDisable
Disables the CAN controller.
Prototype:
void
ROM_CANDisable(uint32_t ui32Base)
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_CANDisable is a function pointer located at ROM_CANTABLE[3].
Parameters:
ui32Base is the base address of the CAN controller to disable.
Description:
Disables the CAN controller for message processing. When disabled, the controller will no
longer automatically process data on the CAN bus. The controller can be restarted by calling
ROM_CANEnable(). The state of the CAN controller and the message objects in the controller
are left as they were before this call was made.
Returns:
None.
April 8, 2013 57
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