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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
349 of 808
NXP Semiconductors
UM10360
Chapter 16: LPC17xx CAN1/2
A write access to all section configuration registers is only possible during the Acceptance
Filter Off and Bypass Mode. Read access is allowed in all Acceptance Filter Modes.
11.1 Acceptance filter Off mode
The Acceptance Filter Off Mode is typically used during initialization. During this mode an
unconditional access to all registers and to the Look-up Table RAM is possible. With the
Acceptance Filter Off Mode, CAN messages are not accepted and therefore not stored in
the Receive Buffers of active CAN Controllers.
11.2 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.
11.3 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.
11.4 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
.
12. 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.
Table 321. 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