Datasheet

UM10398 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2014. All rights reserved.
User manual Rev. 12.3 — 10 June 2014 309 of 547
NXP Semiconductors
UM10398
Chapter 16: LPC111x/LPC11Cxx C_CAN controller
2. drives CAN sample point signal to monitor the CAN controller’s timing.
3. drives recessive constant value.
4. drives dominant constant value.
The last two functions, combined with the readable CAN receive pin CAN_RXD, can be
used to check the CAN bus’ physical layer.
The output mode of pin CAN_TXD is selected by programming the Test Register bits TX1
and TX0 as described Section 16.6.1.6
.
Remark: The three test functions for pin CAN_TXD interfere with all CAN protocol
functions. The CAN_TXD pin must be left in its default function when CAN message
transfer or any of the test modes Loo-back mode, Silent mode, or Basic mode are
selected.
16.7.3 CAN message handler
The Message handler controls the data transfer between the Rx/Tx Shift Register of the
CAN Core, the Message RAM and the IFx Registers, see Figure 65
.
The message handler controls the following functions:
• Data Transfer between IFx Registers and the Message RAM
• Data Transfer from Shift Register to the Message RAM
• Data Transfer from Message RAM to Shift Register
• Data Transfer from Shift Register to the Acceptance Filtering unit
• Scanning of Message RAM for a matching Message Object
• Handling of TXRQST flags
• Handling of interrupts