NXP Semiconductors LPC24XX UM10237 - Manual (Page 498)

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User manual Rev. 04 — 26 August 2009 498 of 792
NXP Semiconductors
UM10237
Chapter 18: LPC24XX CAN controllers CAN1/2
12.2 Acceptance filter Bypass mode
The Acceptance Filter Bypass Mode can be used for example to change the acceptance
filter configuration during a running system, e.g. change of identifiers in the ID-Look-up
Table memory. During this re-configuration, software acceptance filtering has to be used.
It is recommended to use the ID ready Interrupt (ID Index) and the Receive Interrupt (RI).
In this mode all CAN message are accepted and stored in the Receive Buffers of active
CAN Controllers.
12.3 Acceptance filter Operating mode
The Acceptance Filter is in Operating Mode when neither the AccOff nor the AccBP in the
Configuration Register is set and the eFCAN = 0.
12.4 FullCAN mode
The Acceptance Filter is in Operating Mode when neither the AccOff nor the AccBP in the
Configuration Register is set and the eFCAN = 1. More details on FullCAN mode are
available in
Section 18–17 “FullCAN mode” .
13. Sections of the ID look-up table RAM
Four 12-bit section configuration registers (SFF_sa, SFF_GRP_sa, EFF_sa,
EFF_GRP_sa) are used to define the boundaries of the different identifier sections in the
ID-Look-up Table Memory. The fifth 12-bit section configuration register, the End of Table
address register (ENDofTable) is used to define the end of all identifier sections. The End
of Table address is also used to assign the start address of the section where FullCAN
Message Objects, if enabled are stored.
14. ID look-up table RAM
The Whole ID Look-up Table RAM is only word accessible. A write access is only possible
during the Acceptance Filter Off or Bypass Mode. Read access is allowed in all
Acceptance Filter Modes.
Table 442. Section configuration register settings
ID-Look up Table Section Register Value Section
status
FullCAN (Standard Frame Format) Identifier Section SFF_sa = 0x000 disabled
> 0x000 enabled
Explicit Standard Frame Format Identifier Section SFF_GRP_sa = SFF_sa disabled
> SFF_sa enabled
Group of Standard Frame Format Identifier Section EFF_sa = SFF_GRP_sa disabled
> SFF_GRP_sa enabled
Explicit Extended Frame Format Identifier Section EFF_GRP_sa = EFF_sa disabled
> EFF_sa enabled
Group of Extended Frame Format Identifier Section ENDofTable = EFF_GRP_sa disabled
> EFF_GRP_sa enabled