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 294 of 547
NXP Semiconductors
UM10398
Chapter 16: LPC111x/LPC11Cxx C_CAN controller
[1] When a message number that is not valid is written into the Command request registers, the message
number will be transformed into a valid value and that message object will be transferred.
16.6.2.3 CAN message interface command mask registers
The control bits of the IFx Command Mask Register specify the transfer direction and
select which of the IFx Message Buffer Registers are source or target of the data
transfer.The functions of the register bits depend on the transfer direction (read or write)
which is selected in the WR/RD bit (bit 7) of this Command mask register.
Select the WR/RD to
one for the Write transfer direction (write to message RAM)
zero for the Read transfer direction (read from message RAM)
Table 255. CAN message interface command request registers (CANIF1_CMDREQ, address
0x4005 0020 and CANIF2_CMDREQ, address 0x4005 0080) bit description
Bit Symbol Value Description Reset
Value
Access
5:0 MN Message number
0x01 - 0x20 = Valid message numbers. The
message object in the message RAM is selected
for data transfer.
0x00 = Not a valid message number. This value is
interpreted as 0x20.
[1]
0x21 - 0x3F = Not a valid message number. This
value is interpreted as 0x01 - 0x1F.
[1]
0x00 R/W
14:6 - reserved - -
15 BUSY BUSY flag 0 RO
0 Done. Set to zero by hardware when read/write
action to this Command request register has
finished.
1 Busy. Set to one by hardware when writing to this
Command request register.
31:16 - - Reserved - -
Table 256. CAN message interface command mask registers (CANIF1_CMDMSK_W, address
0x4005 0024 and CANIF2_CMDMSK_W, address 0x4005 0084) bit description for
write direction
Bit Symbol Value Description Reset
value
Access
0 DATA_B Access data bytes 4-7 0 R/W
0 Unchanged. Data bytes 4-7 unchanged.
1 Transfer. Transfer data bytes 4-7 to message
object.
1 DATA_A Access data bytes 0-3 0 R/W
0 Unchanged. Data bytes 0-3 unchanged.
1 Transfer. Transfer data bytes 0-3 to message
object.