2000 Jan 04 46
Philips Semiconductors Product specification
Stand-alone CAN controller SJA1000
Fig.10 Single filter configuration, receiving extended frame messages.
handbook, full pagewidth
MGK625
7
MSB LSB
6543210
CAN ADDRESS 16; ACR0
7
MSB LSB
6543
unused
unused
210
CAN ADDRESS 17; ACR1
7
MSB LSB
6543210
CAN ADDRESS 18; ACR2
7
MSB LSB
6543210
CAN ADDRESS 19; ACR3
76543210
CAN ADDRESS 20; AMR0
76543210
CAN ADDRESS 21; AMR1
76543210
CAN ADDRESS 22; AMR2
76543210
CAN ADDRESS 23; AMR3
ID.28
ID.27
ID.26
ID.25
ID.24
ID.23
ID.22
ID.21
ID.20
ID.19
ID.18
ID.16
ID.14
ID.15
ID.13
ID.17
ID.12
ID.11
ID.10
ID.9
ID.8
ID.7
ID.6
ID.5
ID.4
ID.3
ID.2
ID.1
ID.0
RTR
&
1
= 1
logic 1 = accepted
logic 0 = not accepted
message bit
acceptance code bit
acceptance mask bit
ACR = Acceptance Code Register
AMR = Acceptance Mask Register
6.4.15.2 Dual filter configuration
In this filter configuration two short filters can be defined.
A received message is compared with both filters to
decide, whether this message should be copied into the
receive buffer or not. If at least one of the filters signals an
acceptance, the received message becomes valid. The bit
correspondences between the filter bytes and the
message bytes depends on the currently received frame
format.
Standard frame: if a standard frame message is received,
the two defined filters are looking different. The first filter
compares the complete standard identifier including the
RTR bit and the first data byte of the message. The second
filter just compares the complete standard identifier
including the RTR bit.
For a successful reception of a message, all single bit
comparisons of at least one complete filter have to signal
acceptance. In case of a set RTR bit or a data length code
of logic 0 no data byte is existing. Nevertheless a message
may pass filter 1, if the first part up to the RTR bit signals
acceptance.
If no data byte filtering is required for filter 1, the four least
significant bits of AMR1 and AMR3 have to be set to
logic 1 (don’t care). Then both filters are working
identically using the standard identifier range including the
RTR bit.
