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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
327 of 808
NXP Semiconductors
UM10360
Chapter 16: LPC17xx CAN1/2
Table 298. CAN Command Register (CAN1CMR - address 0x4004 4004, CAN2CMR - address 0x4004 8004) bit
description
Bit
Symbol Value
Function
Reset
Value
RM
Set
TR
Transmission Request.
0
0
0 (absent)
No transmission request.
1 (present)
The message, previously written to the CANxTFI, CANxTID, and
optionally the CANxTDA and CANxTDB registers, is queued for
transmission from the selected Transmit Buffer. If at two or all three
of STB1, STB2 and STB3 bits are selected when TR=1 is written,
Transmit Buffer will be selected based on the chosen priority
scheme (for details see
Section 16–5.3 “Transmit Buffers (TXB)”
AT
Abort Transmission.
0
0
0 (no action)
Do not abort the transmission.
1 (present)
if not already in progress, a pending Transmission Request for the
selected Transmit Buffer is cancelled.
RRB
Release Receive Buffer.
0
0
0 (no action)
Do not release the receive buffer.
1 (released)
The information in the Receive Buffer (consisting of CANxRFS,
CANxRID, and if applicable the CANxRDA and CANxRDB registers)
is released, and becomes eligible for replacement by the next
received frame. If the next received frame is not available, writing
this command clears the RBS bit in the Status Register(s).
CDO
Clear Data Overrun.
0
0
0 (no action)
Do not clear the data overrun bit.
1 (clear)
The Data Overrun bit in Status Register(s) is cleared.
SRR
Self Reception Request.
0
0
0 (absent)
No self reception request.
1 (present)
The message, previously written to the CANxTFS, CANxTID, and
optionally the CANxTDA and CANxTDB registers, is queued for
transmission from the selected Transmit Buffer and received
simultaneously. This differs from the TR bit above in that the receiver
is not disabled during the transmission, so that it receives the
message if its Identifier is recognized by the Acceptance Filter.
5
STB1
Select Tx Buffer 1.
0
0
0 (not selected)
Tx Buffer 1 is not selected for transmission.
1 (selected)
Tx Buffer 1 is selected for transmission.
6
STB2
Select Tx Buffer 2.
0
0
0 (not selected)
Tx Buffer 2 is not selected for transmission.
1 (selected)
Tx Buffer 2 is selected for transmission.
7
STB3
Select Tx Buffer 3.
0
0
0 (not selected)
Tx Buffer 3 is not selected for transmission.
1 (selected)
Tx Buffer 3 is selected for transmission.