
FlexCAN
Freescale Semiconductor
23-19
Table 23-12. Message Buffer Code for Rx Buffers
Rx Code
BEFORE
Rx New Frame
Description
Rx Code
AFTER
Rx New Frame
Comment
0000
INACTIVE: MB is not
active.
—
MB does not participate in the matching process.
0100
EMPTY: MB is active
and empty.
0010
MB participates in the matching process. When a
frame is received successfully, the code is
automatically updated to FULL.
0010
FULL: MB is full.
0010
The act of reading the control & status (C/S) word
followed by unlocking the MB does not make the
code return to EMPTY. It remains FULL. If a new
frame is written to the MB after the C/S word was
read and the MB was unlocked, the code remains
FULL.
0110
If the MB is FULL and a new frame should be written
into this MB before the CPU had time to read it, the
MB is overwritten, and the code is automatically
updated to OVERRUN.
0110
OVERRUN: A frame
was overwritten into a
full buffer.
0010
If the code indicates OVERRUN but the CPU reads
the C/S word and then unlocks the MB, when a new
frame is written to the MB, the code returns to FULL.
0110
If the code already indicates OVERRUN, and yet
another new frame must be written, the MB is
overwritten again, and the code remains OVERRUN.
0XY1
1
1
For transmit message buffers (see
), the BUSY bit should be ignored upon read.
BUSY: Flexcan is
updating the contents
of the MB with a new
receive frame.
The CPU should not try
to 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).
Table 23-13. Message Buffer Code for Tx Buffers
MBn[RTR]
Initial Tx
Code
Code After
Successful
Transmission
Description
X
1000
—
INACTIVE: Message buffer not ready for transmit and
participates in the arbitration process.
0
1100
1000
Data frame to be transmitted once, unconditionally. After
transmission, the MB automatically returns to the INACTIVE
state.
1
1100
0100
Remote frame to be transmitted unconditionally once, and
message buffer becomes an Rx message buffer with the same
ID for data frames.
MCF5329 Reference Manual, Rev 3
Summary of Contents for MCF5329
Page 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...