Chapter 22 FlexCAN
MPC5602P Microcontroller Reference Manual, Rev. 4
Freescale Semiconductor
541
0XY1
1
BUSY: Flexcan is updating
the contents of the MB. The
CPU must not access the MB.
0010
An EMPTY buffer was written with a new frame
(XY was 01).
0110
A FULL/OVERRUN buffer was overwritten (XY
was 11).
1
Note that for Tx MBs (see
), the BUSY bit should be ignored upon read, except when AEN bit is set in
the MCR.
Table 22-7. Message Buffer code for Tx buffers
RTR
Initial Tx
code
Code after
successful
transmission
Description
X
1000
–
INACTIVE: MB does not participate in the arbitration process.
X
1001
–
ABORT: MB was configured as Tx and CPU aborted the transmission.
This code is only valid when AEN bit in MCR is asserted. MB does not
participate in the arbitration process.
0
1100
1000
Transmit data frame unconditionally once. After transmission, the MB
automatically returns to the INACTIVE state.
1
1100
0100
Transmit remote frame unconditionally once. After transmission, the MB
automatically becomes an Rx MB with the same ID.
0
1010
1010
Transmit a data frame whenever a remote request frame with the same
ID is received. This MB participates simultaneously in both the matching
and arbitration processes. The matching process compares the ID of the
incoming remote request frame with the ID of the MB. If a match occurs
this MB is allowed to participate in the current arbitration process and the
Code field is automatically updated to ‘1110’ to allow the MB to
participate in future arbitration runs. When the frame is eventually
transmitted successfully, the Code automatically returns to ‘1010’ to
restart the process again.
0
1110
1010
This is an intermediate code that is automatically written to the MB by the
MBM as a result of match to a remote request frame. The data frame will
be transmitted unconditionally once and then the code will automatically
return to ‘1010’. The CPU can also write this code with the same effect.
Table 22-8. MB0–MB31 addresses
Address
Register
Address
Register
Base + 0x0080
MB0
Base + 0x0180
MB16
Base + 0x0090
MB1
Base + 0x0190
MB17
Base + 0x00A0
MB2
Base + 0x01A0
MB18
Base + 0x00B0
MB3
Base + 0x01B0
MB19
Base + 0x00C0
MB4
Base + 0x01C0
MB20
Table 22-6. Message buffer code for Rx buffers (continued)
Rx Code
BEFORE
Rx New Frame
Description
Rx Code
AFTER
Rx New Frame
Comment