If3 Observation Register (Can If3Obs); If2 Data B Register (Can If2Datb) [Offset = 0X134]; If3 Observation Register (Can If3Obs) [Offset = 0X140]; If3 Observation Register Field Descriptions - Texas Instruments Concerto F28M35 Series Technical Reference Manual

CAN Control Registers
31
15
LEGEND: R = Read; WP = Protected Write (protected by Busy bit); -n = value after reset

23.15.19 IF3 Observation Register (CAN IF3OBS)

The IF3 register set can automatically be updated with received message objects without the need to
initiate the transfer from Message RAM by CPU (see also
The observation flags (Bits [4:0]) in the IF3 Observation register are used to determine, which data
sections of the IF3 Interface Register set have to be read in order to complete a DMA read cycle. After all
marked data sections are read, the CAN is enabled to update the IF3 Interface Register set with new data.
Any access order of single bytes or half-words is supported. When using byte or half-word accesses, a
data section is marked as completed, if all bytes are read.
NOTE: If IF3 Update Enable is used and no Observation flag is set, the corresponding message
objects will be copied to IF3 without activating the DMA request line and without waiting for
DMA read accesses.
A write access to this register aborts a pending DMA cycle by resetting the DMA line and enables
updating of IF3 Interface Register set with new data. To avoid data inconsistency, the DMA controller
should be disabled before reconfiguring IF3 observation register.
Figure 23-44. IF3 Observation Register (CAN IF3OBS) [offset = 0x140]
31
15
LEGEND: R = Read; R/W = Read/Write; -n = value after reset
Bit Field
31-5 Reserved
4 DataB
3 DataA
2 Ctrl
1 Arb
1562
M3 Controller Area Network (CAN)
Figure 23-43. IF2 Data B Register (CAN IF2DATB) [offset = 0x134]
Data 7
R/WP-0
Data 5
R/WP-0
Reserved
R-0
Table 23-22. IF3 Observation Register Field Descriptions
Value Description
Reserved
Data B read observation
0 Data B section has not to be read.
1 Data B section has to be read to enable next IF3 update.
Data A read observation
0 Data A section has not to be read.
1 Data A section has to be read to enable next IF3 update.
Ctrl read observation
0 Ctrl section has not to be read.
1 Ctrl section has to be read to enable next IF3 update.
Arbitration data read observation
0 Arbitration data has not to be read.
1 Arbitration data has to be read to enable next IF3 update.
Copyright © 2012–2019, Texas Instruments Incorporated
24 23
8 7
Section 23.14.1).
Reserved
R-0
5
SPRUH22I – April 2012 – Revised November 2019
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Data 6
R/WP-0
Data 4
R/WP-0
4 3 2 1
DataB DataA Ctrl Arb
R/W-0 R/W-0 R/W-0 R/W-0
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16
0
16
0
Mask
R/W-0