NXP Semiconductors LPC24XX UM10237 - Manual (Page 475)

UM10237_4 © NXP B.V. 2009. All rights reserved.
User manual Rev. 04 — 26 August 2009 475 of 792
NXP Semiconductors
UM10237
Chapter 18: LPC24XX CAN controllers CAN1/2
In the following register tables, the column “Reset Value” shows how a hardware reset
affects each bit or field, while the column “RM Set” indicates how each bit or field is
affected if software sets the RM bit, or RM is set because of a Bus-Off condition. Note that
while hardware reset sets RM, in this case the setting noted in the “Reset Value” column
prevails over that shown in the “RM Set” column, in the few bits where they differ. In both
columns, X indicates the bit or field is unchanged.
8.1 Mode Register (CAN1MOD - 0xE004 4000, CAN2MOD - 0xE004 8000)
The contents of the Mode Register are used to change the behavior of the CAN
Controller. Bits may be set or reset by the CPU that uses the Mode Register as a
read/write memory. Reserved Bits are read as 0 and should be written as 0.
IER Interrupt Enable Interrupt Enable Interrupt Enable Interrupt Enable
BTR Bus Timing - Bus Timing Bus Timing
EWL Error Warning Limit - Error Warning Limit Error Warning Limit
SR Status - Status -
RFS Rx Info and Index - Rx Info and Index Rx Info and Index
RID Rx Identifier - Rx Identifier Rx Identifier
RDA Rx Data - Rx Data Rx Data
RDB Rx Info and Index - Rx Info and Index Rx Info and Index
TFI1 Tx Info1 Tx Info Tx Info Tx Info
TID1 Tx Identifier Tx Identifier Tx Identifier Tx Identifier
TDA1 Tx Data Tx Data Tx Data Tx Data
TDB1 Tx Data Tx Data Tx Data Tx Data
Table 419. Access to CAN1 and CAN2 controller registers
Generic
Name Operating Mode Reset Mode
Read Write Read Write
Table 420. Mode register (CAN1MOD - address 0xE004 4000, CAN2MOD - address 0xE004 8000) bit description
Bit Symbol Value Function Reset
Value RM
Set
0 RM [1][6] Reset Mode. 1 1
0(normal) The CAN Controller is in the Operating Mode, and certain registers can not be
written.
1(reset) CAN operation is disabled, writable registers can be written and the current
transmission/reception of a message is aborted.
1 LOM [3][2]
[6]
Listen Only Mode. 0 x
0(normal) The CAN controller acknowledges a successfully received message on the
CAN bus. The error counters are stopped at the current value.
1(listen only) The controller gives no acknowledgment, even if a message is successfully
received. Messages cannot be sent, and the controller operates in “error
passive” mode. This mode is intended for software bit rate detection and “hot
plugging”.