Register 30: CAN Transmission Request 1 (CANTXRQ1), offset 0x100
Register 31: CAN Transmission Request 2 (CANTXRQ2), offset 0x104
The
CANTXRQ1
and
CANTXRQ2
registers hold the
TXRQST
bits of the 32 message objects. By
reading out these bits, the CPU can check which message object has a transmission request pending.
The
TXRQST
bit of a specific message object can be changed by three sources: (1) the CPU via the
CANIFnMCTL
register, (2) the message handler state machine after the reception of a remote
frame, or (3) the message handler state machine after a successful transmission.
The
CANTXRQ1
register contains the
TXRQST
bits of the first 16 message objects in the message
RAM; the
CANTXRQ2
register contains the
TXRQST
bits of the second 16 message objects.
CAN Transmission Request n (CANTXRQn)
CAN0 base: 0x4004.0000
CAN1 base: 0x4004.1000
Offset 0x100
Type RO, reset 0x0000.0000
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
reserved
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
Type
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Reset
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
TXRQST
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
Type
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Reset
Description
Reset
Type
Name
Bit/Field
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
0x0000
RO
reserved
31:16
Transmission Request Bits
Description
Value
The corresponding message object is not waiting for
transmission.
0
The transmission of the corresponding message object
is requested and is not yet done.
1
0x0000
RO
TXRQST
15:0
1403
June 18, 2014
Texas Instruments-Production Data
Tiva
™
TM4C1294NCPDT Microcontroller