MPC5200B Users Guide, Rev. 1
19-6 Freescale Semiconductor
Memory Map / Register Definition
Bit Name Description
0 RXFRM Received Frame—flag bit is read and clear only. It is set when a receiver has received a valid
message correctly, independently of the filter configuration. Once set, it remains set until
cleared by software or reset. Clear by writing 1 to the bit. This bit is not valid in loop-back mode.
0 = No valid message was received since last clearing this flag
1 = A valid message was received since last clearing of this flag
1 RXACT Receiver Active Status—flag bit indicates MSCAN is receiving a message. The flag is
controlled by the receiver front end. This bit is not valid in loop-back mode.
0 = MSCAN is transmitting or idle
1 = MSCAN is receiving a message (including when arbitration is lost)
Note: See the Bosch CAN 2.0A/B protocol specification dated September 1991 for a detailed
definition of transmitter and receiver states.
2 CSWAI CAN Stops in Wait Mode—enabling this bit allows lower power consumption in wait mode by
disabling all clocks at the bus interface to the MSCAN module.
0 = Module is not affected during WAIT mode
1 = Module ceases to be clocked during WAIT mode
3 SYNCH Synchronized Status—flag bit indicates whether MSCAN is synchronized to the CAN bus and,
as such, can participate in the communication process. It is set and cleared by MSCAN.
0 = MSCAN is not synchronized to the CAN bus
1 = MSCAN is synchronized to the CAN bus
4 TIME Timer Enable—bit activates an internal 16-bit wide free running timer, clocked by the bit-clock.
If timer is enabled, a 16-bit time stamp is assigned to each transmitted/received message
within the active Tx/Rx buffer. As soon as a message is acknowledged on CAN, the time stamp
is written to the highest bytes ($_E, $_F) in the appropriate buffer. The internal timer is reset
(all bits set to “0”) when Initialization Mode is active.
0 = Disable internal MSCAN timer
1 = Enable internal MSCAN timer
5 WUPE WakeUp Enable—bit lets MSCAN restart when being locked in idle state during sleep mode
and traffic on CAN is detected.
0 = WakeUp disabled—MSCAN ignores traffic on CAN
1 = WakeUp enabled—MSCAN is able to restart
6 SLPRQ Sleep Mode Request—bit requests MSCAN enter sleep mode, an internal power saving mode.
If a CAN message transfer is occurring when receiving this request, MSCAN waits until end of
current message before entering sleep mode. The module indicates entry to Sleep Mode by
setting SLPAK=1. MSCAN Control 1 Register (CANCTL1). Sleep mode is active until the CPU
clears SLPRQ or, depending on the WUPE bit setting, MSCAN detects CAN bus activity and
clears SLPRQ.
0 = Running—MSCAN functions normally
1 = Sleep Mode Request—MSCAN locks in idle state
7 INITRQ Initialization Mode Request—When the CPU sets this bit, MSCAN skips to initialization mode.
Any ongoing transmission or reception is aborted and bus synchronization lost. The module
indicates entry to initialization mode by setting INITAK=1