UM10360 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
User manual Rev. 3 — 19 December 2013 369 of 841
NXP Semiconductors
UM10360
Chapter 16: LPC176x/5x CAN1/2
Controllers start a Remote Frame transmission with the same identifier simultaneously.
For reasons of compatibility no DLC > 8 should be used. If a value greater than 8 is
selected, 8 bytes are transmitted in the data frame with the Data Length Code specified in
DLC. The range of the Data Byte Count is 0 to 8 bytes and is coded as follows:
(12)
16.7.14 CAN Transmit Identifier register (CAN1TID[1/2/3] -
0x4004 40[34/44/54], CAN2TID[1/2/3] - 0x4004 80[34/44/54])
When the corresponding TBS bit in CANxSR is 1, software can write to one of these
registers to define the Identifier field of the next transmit message. Bits not listed read as 0
and should be written as 0. The register assumes two different formats depending on the
FF bit in CANTFI.
In Standard Frame Format messages, the CAN Identifier consists of 11 bits (ID.28 to
ID.18), and in Extended Frame Format messages, the CAN identifier consists of 29 bits
(ID.28 to ID.0). ID.28 is the most significant bit, and it is transmitted first on the bus during
the arbitration process. The Identifier acts as the message's name, used in a receiver for
acceptance filtering, and also determines the bus access priority during the arbitration
process.
16.7.15 CAN Transmit Data register A (CAN1TDA[1/2/3] - 0x4004 40[38/48/58],
CAN2TDA[1/2/3] - 0x4004 80[38/48/58])
When the corresponding TBS bit in CANSR is 1, software can write to one of these
registers to define the first 1 - 4 data bytes of the next transmit message. The Data Length
Code defines the number of transferred data bytes. The first bit transmitted is the most
significant bit of TX Data Byte 1.
Table 331. CAN Transfer Identifier register (CAN1TID[1/2/3] - address 0x4004 40[34/44/54], CAN2TID[1/2/3] - address
0x4004 80[34/44/54]) bit description
Bit Symbol Function Reset Value RM Set
10:0 ID The 11-bit Identifier to be sent in the next transmit message. 0 X
31:11 - Reserved, user software should not write ones to reserved bits. The value read
from a reserved bit is not defined.
NA
Table 332. Transfer Identifier register when FF = 1
Bit Symbol Function Reset Value RM Set
28:0 ID The 29-bit Identifier to be sent in the next transmit message. 0 X
31:29 - Reserved, user software should not write ones to reserved bits. The value read
from a reserved bit is not defined.
NA
To Next Page
Loading...
Need help?
General
