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D
RAFT
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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
318 of 571
NXP Semiconductors
UM10316
Chapter 21: LPC29xx CAN 0/1
[1]
A write-access to the RPM, TPM, STM and LOM registers is possible only if soft reset mode has previously
been entered.
[2]
In cases where the same transmit priority or the same ID is chosen for more than one buffer, the transmit
buffer with the lowest buffer number is sent first.
[3]
This mode of operation forces the CAN controller to be error-passive. Message transmission is not
possible.
[4]
During a hardware reset or when the bus status bit is set to 1 (bus-off), the soft reset mode bit is set to 1
(present). After the soft reset mode bit has been set to 0 the CAN controller will wait for:
a) one occurrence of bus-free signal (11 recessive bits) if the preceding reset has been caused by a
hardware reset or a CPU-initiated reset.
b) 128 occurrences of bus-free signal, if the preceding reset has been caused by a CAN controller-initiated
bus-off, before re-entering the bus-on mode
[5]
When entering soft reset mode it is not possible to access any other register within the same instruction.
Table 267. CCMODE register bit description (CCMODE, address 0xE008 0000 (CAN0) and
0xE008 1000 (CAN1))
* = reset value; **both reset value and soft reset mode value
Bit
Symbol
Access
Value
Description
31 to 6
reserved
R
-
Reserved; do not modify. Read as logic 0
5
RPM
R/W
Reverse polarity mode
1
RXDC and TXDC pins are HIGH for a dominant
bit
0*
RXDC and TXDC pins are LOW for a dominant
bit
4
reserved
R
-
Reserved; do not modify. Read as logic 0
3
TPM
R/W
Transmit priority mode
1
Priority depends on the contents of the transmit
priority register within the transmit buffer
0*
Transmit priority depends on the CAN identifier
2
STM
R/W
Self-test mode
1
The controller will consider a transmitted
message successful if there is no
acknowledgment. Use this state in conjunction
with the self-reception request bit in the CAN
controller command register
0*
Transmitted message must be acknowledged
to be considered as successful
1
LOM
R/W
Listen-only mode
1
The controller gives no acknowledgment on
CAN even if a message is successfully
received. Messages cannot be sent, and the
controller operates in error-passive mode
0*
The CAN controller acknowledges a
successfully received message
0
RM
R/W
Soft reset mode
1**
CAN operation is disabled, and writable
registers can be written to
0
CAN controller operates and certain registers
cannot be written to