DR
AFT
DR
AFT
DRAFT
DR
D
RAFT
DRAFT
DRA
FT DRAF
D
RAFT DRAFT DRAFT DRAFT DRAFT D
DRAFT
D
RAFT DRA
FT DRAFT DRAFT DRAFT DRA
UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
307 of 571
NXP Semiconductors
UM10316
Chapter 21: LPC29xx CAN 0/1
A message transmission is initiated by setting the self-reception request bit SRR in
conjunction with the selected message buffer(s) STB3, STB2 and STB1.
8.
CAN global acceptance filter
The global acceptance filter provides a look-up for received identifiers - called acceptance
filtering in CAN terminology - for all the CAN controllers. It includes a CAN ID look-up table
memory in which software maintains one to five sections of identifiers. The CAN ID
look-up table memory is 2 kB (512 words, each of 32 bits). It can contain up to 1024
standard frame identifiers (SFFs) or 512 extended frame identifiers (EFFs) or a mixture of
both types. Note that the whole CAN ID look-up table memory is only word-accessible.
The CAN ID look-up table memory is structured into up to five sections, each of which lists
the identifiers of a certain CAN message type (see
Five start -address registers exist to indicate the boundaries of the different sections within
the ID look-up table memory. These registers store the offset for the base address
CANAFM (see
). The standard frame-format FullCAN identifier section always
starts at the offset 00h, with the following sections starting as defined in the start-address
registers. The look-up table ends with the FullCAN message object section, which starts
at the offset CAEOTA. A non-existent section is indicated by equal values in consecutive
start-address registers.
See
for the structure of the CAN ID look-up table memory sections.
Fig 73. Local self-test (example for high-speed CAN bus)
Transceiver
RX Buffer
TX Buffer
TX Buffer
TX Buffer
Table 259. CAN ID look-up table memory sections
Name of Section
Reception method
CAN message
frame format
Explicit IDs or
group of IDs
Standard Frame Format
FullCAN identifier section
stored directly in
memory
Standard Frame
Format (SFF)
Explicit
Standard Frame Format
explicit identifier section
buffered
Standard Frame
Format (SFF)
Explicit
Standard Frame Format
group identifier section
buffered
Standard Frame
Format (SFF)
Group
Extended Frame Format
explicit identifier section
buffered
Extended Frame
Format (EFF)
Explicit
Extended Frame Format
group identifier section
buffered
Extended Frame
Format (EFF)
Group