FlexCAN
MCF52277 Reference Manual, Rev. 1
23-12
Freescale Semiconductor
23.3.4
Rx Mask Registers (RXGMASK, RX14MASK, RX15MASK)
NOTE
These registers are provided for legacy software by clearing. For more
configurability use the individual masking registers instead by setting
CANMCR[BCC]. See
Section 23.3.10, “Rx Individual Masking Registers
These registers are used as acceptance masks for received frame IDs if CANMCR[BCC] is cleared. (If
CANMCR[BCC] is set, these registers are reserved and do not affect FlexCAN operation.) Three masks
are defined: a global mask (RXGMASK) used for Rx buffers 0–13 and two separate masks for buffers 14
(RX14MASK) and 15 (RX15MASK). The meaning of each mask bit is the following:
MI
n
bit = 0: The corresponding incoming ID bit is don’t care.
MI
n
bit = 1: The corresponding ID bit is checked against the incoming ID bit, to see if a match exists.
These masks are used for standard and extended ID formats. The value of the mask registers should not be
changed while in normal operation (only while in freeze mode), as locked frames that matched a message
buffer (MB) through a mask may be transferred into the MB (upon release) but may no longer match.
Table 23-5. Mask Examples for Normal/Extended Messages
Base ID
ID28.................ID18
IDE
Extended ID
ID17......................................ID0
Match
MB2-ID
1 1 1 1 1 1 1 1 0 0 0
0
MB3-ID
1 1 1 1 1 1 1 1 0 0 0
1
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
MB4-ID
0 0 0 0 0 0 1 1 1 1 1
0
MB5-ID
0 0 0 0 0 0 1 1 1 0 1
1
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
MB14-ID
1 1 1 1 1 1 1 1 0 0 0
1
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
Rx_Global_Mask
1 1 1 1 1 1 1 1 1 1 0
1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1
Rx_Msg in
1
1 1 1 1 1 1 1 1 0 0 1
1
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
MB3
1
1
Match for Extended Format (MB3).
Rx_Msg in
2
1 1 1 1 1 1 1 1 0 0 1
0
MB2
2
2
Match for Normal Format. (MB2).
Rx_Msg in
3
1 1 1 1 1 1 1 1 0 0 1
1
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 0
3
3
Mismatch for MB3 because of ID0.
Rx_Msg in
4
0 1 1 1 1 1 1 1 0 0 0
0
4
4
Mismatch for MB2 because of ID28.
Rx_Msg in
5
0 1 1 1 1 1 1 1 0 0 0
1
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
MB14
5
5
Mismatch for MB3 because of ID28, Match for MB14 (Uses RX14MASK).
RX14MASK
0 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0
Rx_Msg in
6
1 0 1 1 1 1 1 1 0 0 0
1
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
6
Rx_Msg in
7
0 1 1 1 1 1 1 1 0 0 0
1
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
MB14
7
Summary of Contents for MCF52277
Page 22: ...MCF52277 Reference Manual Rev 1 Freescale Semiconductor xxii...
Page 32: ...MCF52277 Reference Manual Rev 0 xxxii Freescale Semiconductor...
Page 60: ...Signal Descriptions MCF52277 Reference Manual Rev 1 2 16 Freescale Semiconductor...
Page 128: ...Static RAM SRAM MCF52277 Reference Manual Rev 1 6 6 Freescale Semiconductor...
Page 140: ...Clock Module MCF52277 Reference Manual Rev 1 7 12 Freescale Semiconductor...
Page 172: ...Chip Configuration Module CCM MCF52277 Reference Manual Rev 1 9 16 Freescale Semiconductor...
Page 180: ...Serial Boot Facility SBF MCF52277 Reference Manual Rev 1 10 8 Freescale Semiconductor...
Page 188: ...Reset Controller Module MCF52277 Reference Manual Rev 1 11 8 Freescale Semiconductor...
Page 210: ...Crossbar Switch XBS MCF52277 Reference Manual Rev 1 13 8 Freescale Semiconductor...
Page 542: ...FlexCAN MCF52277 Reference Manual Rev 1 23 32 Freescale Semiconductor...
Page 724: ...UART Modules MCF52277 Reference Manual Rev 1 30 34 Freescale Semiconductor...
Page 740: ...I2 C Interface MCF52277 Reference Manual Rev 1 31 16 Freescale Semiconductor...
Page 790: ...Debug Module MCF52277 Reference Manual Rev 1 32 50 Freescale Semiconductor...