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Chapter 16
CAN Controller
User’s Manual U16504EE1V1UD00
Figure 16-48:
Redefinition Control Register (2/2)
Cautions: 1. Keep special programming sequence. Failing to do so can cause inconsistent
data or loss of receive data.
2. Do not change DEF bit and SEL bit at the same time. Change SEL bit only when
DEF bit is cleared.
3. Write first SEL with DEF cleared. Write than SEL with DEF, or use bit manipulation
instruction. Only clear DEF bit by keeping SEL or use bit manipulation instruc-
tion.
Setting the redefinition bit removes the selected receive buffer from the list of possible ID hits during
identifier comparisons.
Setting the DEF bit will not have immediate effect, if DCAN is preparing to store or is already in
progress of storing a received message into the particular buffer. In this case the redefinition request is
ignored for the currently processed message.
The application should monitor the DN flag before requesting the redefinition state for a particular
buffer. A DN flag set indicates a new message that arrived or a new message that is in progress of
being stored to that buffer. The application should be prepared to receive a message immediately after
redefinition state was set. The user can identify this situation because the data new bit (DN) in the
receive buffer will be set. This is of special importance if it is used together with a mask function
because in this case the DCAN also writes the identifier part of the message to the receive buffer. Then
the application needs to re-write the configuration of the message buffer.
SEL3
SEL2
SEL1
SEL0
Buffer selection (n =0...15)
0
0
0
0
Buffer 0 is selected for redefinition
0
0
0
1
Buffer 1 is selected for redefinition
0
0
1
0
Buffer 2 is selected for redefinition
0
0
1
1
Buffer 3 is selected for redefinition
0
1
0
0
Buffer 4 is selected for redefinition
0
1
0
1
Buffer 5 is selected for redefinition
0
1
1
0
Buffer 6 is selected for redefinition
0
1
1
1
Buffer 7 is selected for redefinition
1
0
0
0
Buffer 8 is selected for redefinition
1
0
0
1
Buffer 9 is selected for redefinition
1
0
1
0
Buffer 10 is selected for redefinition
1
0
1
1
Buffer 11 is selected for redefinition
1
1
0
0
Buffer 12 is selected for redefinition
1
1
0
1
Buffer 13 is selected for redefinition
1
1
1
0
Buffer 14 is selected for redefinition
1
1
1
1
Buffer 15 is selected for redefinition
Other than above
Setting prohibited