MPC5777C Reference Manual Addendum

MPC5777C Reference Manual
Addendum
Supports maskset 2N45H
Document Number: MPC5777CRMAD
Rev. 1, 12/2015
MPC5777C Reference Manual Addendum, Rev. 1, 12/2015
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Freescale Semiconductor, Inc.
Contents
Section number
Title
Page
Chapter 1
Preface
1.1 Overview...........................................................................................................................................................................7
1.2 Device versions.................................................................................................................................................................7
1.3 Audience...........................................................................................................................................................................8
1.4 Document organization.....................................................................................................................................................8
1.5 Conventions......................................................................................................................................................................8
1.5.1
Numbering systems..............................................................................................................................................8
1.5.2
Typographic notation...........................................................................................................................................9
1.5.3
Special terms........................................................................................................................................................9
1.6 References.........................................................................................................................................................................10
Chapter 2
Platform Configuration Module (PCM)
2.1 PCM memory map and register descriptions....................................................................................................................11
2.1.1
FEC Burst Optimization Master Control Register (PCM_FBOMCR)................................................................12
2.1.2
Bus Bridge Configuration Register 1 (PCM_IAHB_BE1)..................................................................................13
2.1.3
Bus Bridge Configuration Register 2 (PCM_IAHB_BE2)..................................................................................16
Chapter 3
Modular CAN (M_CAN)
3.1 Chip-specific M_CAN information..................................................................................................................................19
3.1.1
M_CAN Message RAM allocation......................................................................................................................19
3.1.2
Introduction..........................................................................................................................................................19
3.1.3
Functional Description.........................................................................................................................................20
3.1.4
External Signals...................................................................................................................................................22
3.2 Overview...........................................................................................................................................................................23
3.2.1
Features................................................................................................................................................................23
3.2.2
Block Diagram.....................................................................................................................................................24
3.2.3
Dual Clock Sources..............................................................................................................................................26
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Section number
3.2.4
Title
Page
Dual Interrupt Lines.............................................................................................................................................26
3.3 Memory Map and Register Description............................................................................................................................27
3.3.1
Core Release Register (M_CAN_CREL)............................................................................................................28
3.3.2
Endian Register (M_CAN_ENDN).....................................................................................................................29
3.3.3
Fast Bit Timing and Prescaler Register (M_CAN_FBTP)..................................................................................30
3.3.4
Test Register (M_CAN_TEST)...........................................................................................................................32
3.3.5
RAM Watchdog Register (M_CAN_RWD)........................................................................................................33
3.3.6
CC Control Register (M_CAN_CCCR)..............................................................................................................34
3.3.7
Bit Timing and Prescaler Register (M_CAN_BTP)............................................................................................36
3.3.8
Timestamp Counter Configuration Register (M_CAN_TSCC)..........................................................................38
3.3.9
Timestamp Counter Value Register (M_CAN_TSCV).......................................................................................38
3.3.10 Timeout Counter Configuration Register (M_CAN_TOCC)..............................................................................39
3.3.11 Timeout Counter Value Register (M_CAN_TOCV)...........................................................................................40
3.3.12 Error Counter Register (M_CAN_ECR)..............................................................................................................41
3.3.13 Protocol Status Register (M_CAN_PSR)............................................................................................................42
3.3.14 Interrupt Register (M_CAN_IR)..........................................................................................................................45
3.3.15 Interrupt Enable Register (M_CAN_IE)..............................................................................................................49
3.3.16 Interrupt Line Select Register (M_CAN_ILS).....................................................................................................52
3.3.17 Interrupt Line Enable Register (M_CAN_ILE)...................................................................................................55
3.3.18 Global Filter Configuration Register (M_CAN_GFC)........................................................................................56
3.3.19 Standard ID Filter Configuration Register (M_CAN_SIDFC)............................................................................57
3.3.20 Extended ID Filter Configuration Register (M_CAN_XIDFC)..........................................................................58
3.3.21 Extended ID and Mask Register (M_CAN_XIDAM).........................................................................................59
3.3.22 High Priority Message Status Register (M_CAN_HPMS)..................................................................................59
3.3.23 New Data 1 Register (M_CAN_NDAT1)...........................................................................................................60
3.3.24 New Data 2 Register (M_CAN_NDAT2)...........................................................................................................61
3.3.25 Rx FIFO 0 Configuration Register (M_CAN_RXF0C)......................................................................................61
3.3.26 Rx FIFO 0 Status Register (M_CAN_RXF0S)....................................................................................................62
3.3.27 Rx FIFO 0 Acknowledge Register (M_CAN_RXF0A)......................................................................................63
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Section number
Title
Page
3.3.28 Rx Buffer Configuration Register (M_CAN_RXBC).........................................................................................64
3.3.29 Rx FIFO 1 Configuration Register (M_CAN_RXF1C)......................................................................................64
3.3.30 Rx FIFO 1 Status Register (M_CAN_RXF1S)....................................................................................................65
3.3.31 Rx FIFO 1 Acknowledge Register (M_CAN_RXF1A)......................................................................................66
3.3.32 Rx Buffer / FIFO Element Size Configuration Register (M_CAN_RXESC).....................................................67
3.3.33 Tx Buffer Configuration Register (M_CAN_TXBC)..........................................................................................69
3.3.34 Tx FIFO/Queue Status Register (M_CAN_TXFQS)...........................................................................................70
3.3.35 Tx Buffer Element Size Configuration (M_CAN_TXESC)................................................................................71
3.3.36 Tx Buffer Request Pending Register (M_CAN_TXBRP)...................................................................................72
3.3.37 Tx Buffer Add Request Register (M_CAN_TXBAR)........................................................................................73
3.3.38 Tx Buffer Cancellation Request Register (M_CAN_TXBCR)...........................................................................73
3.3.39 Tx Buffer Transmission Occurred Register (M_CAN_TXBTO)........................................................................74
3.3.40 Tx Buffer Cancellation Finished Register (M_CAN_TXBCF)...........................................................................74
3.3.41 Tx Buffer Transmission Interrupt Enable Register (M_CAN_TXBTIE)............................................................75
3.3.42 Tx Buffer Cancellation Finished Interrupt Enable Register (M_CAN_TXBCIE)..............................................75
3.3.43 Tx Event FIFO Configuration Register (M_CAN_TXEFC)...............................................................................76
3.3.44 Tx Event FIFO Status Register (M_CAN_TXEFS)............................................................................................77
3.3.45 Tx Event FIFO Acknowledge Register (M_CAN_TXEFA)...............................................................................78
3.4 Message RAM..................................................................................................................................................................78
3.4.1
Rx Buffer and FIFO Element...............................................................................................................................79
3.4.2
Tx Buffer Element...............................................................................................................................................81
3.4.3
Tx Event FIFO Element.......................................................................................................................................83
3.4.4
Standard Message ID Filter Element...................................................................................................................84
3.4.5
Extended Message ID Filter Element..................................................................................................................85
3.5 Functional Description......................................................................................................................................................87
3.5.1
Operating Modes..................................................................................................................................................87
3.5.2
Timestamp Generation.........................................................................................................................................96
3.5.3
Timeout Counter..................................................................................................................................................97
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Section number
Title
Page
3.5.4
Rx Handling.........................................................................................................................................................97
3.5.5
Tx Handling.........................................................................................................................................................108
3.5.6
FIFO Acknowledge Handling..............................................................................................................................114
3.5.7
Interface to DMA Controller................................................................................................................................114
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Chapter 1
Preface
1.1 Overview
For users of maskset 2N45H, this addendum supplements—and must be used in
conjunction with—the latest version of the MPC5777C Reference Manual. The primary
objective of this document is to define the major differences in functionality of maskset
2N45H from maskset 3N45H for software and hardware developers.
The information in this document is subject to change. As with any technical
documentation, it is the reader’s responsibility to ensure he or she is using the most recent
version of the documentation.
To locate any published errata or updates for this document, visit the Freescale Web site
at http://www.freescale.com.
1.2 Device versions
This document is necessary for users of maskset 2N45H. It describes the functionality
and programming model of maskset 2N45H that differ from maskset 3N45H.
For 2N45H, the body chapters in this addendum replace the corresponding chapters of the
latest MPC5777C Reference Manual (document number MPC5777CRM). Other chapters
in the latest MPC5777C Reference Manual accurately describe 2N45H.
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Audience
1.3 Audience
This addendum is intended for system software and hardware developers and applications
programmers who want to develop products with maskset 2N45H of the MPC5777C. It is
assumed that the reader understands operating systems, microprocessor system design,
basic principles of software and hardware, and basic details of the Power Architecture®
developed by Freescale.
1.4 Document organization
This document contains two chapters whose content differs from the corresponding
chapters of the MPC5777C Reference Manual:
• Platform Configuration Module (PCM)
• Modular CAN (M_CAN)
These addendum chapters describe the indicated modules for maskset 2N45H. The
corresponding chapters of the MPC5777C Reference Manual describe the indicated
modules for maskset 3N45H.
1.5 Conventions
1.5.1 Numbering systems
The following suffixes identify different numbering systems:
This suffix
Identifies a
b
Binary number. For example, the binary equivalent of the number 5 is written 101b. In some cases,
binary numbers are shown with the prefix 0b.
d
Decimal number. Decimal numbers are followed by this suffix only when the possibility of confusion
exists. In general, decimal numbers are shown without a suffix.
h
Hexadecimal number. For example, the hexadecimal equivalent of the number 60 is written 3Ch. In
some cases, hexadecimal numbers are shown with the prefix 0x.
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Chapter 1 Preface
1.5.2 Typographic notation
The following typographic notation is used throughout this document:
Example
Description
placeholder, x
Items in italics are placeholders for information that you provide. Italicized text is also used for
the titles of publications and for emphasis. Plain lowercase letters are also used as
placeholders for single letters and numbers.
code
Fixed-width type indicates text that must be typed exactly as shown. It is used for instruction
mnemonics, directives, symbols, subcommands, parameters, and operators. Fixed-width type
is also used for example code. Instruction mnemonics and directives in text and tables are
shown in all caps; for example, BSR.
SR[SCM]
A mnemonic in brackets represents a named field in a register. This example refers to the
Scaling Mode (SCM) field in the Status Register (SR).
REVNO[6:4], XAD[7:0]
Numbers in brackets and separated by a colon represent either:
• A subset of a register's named field
For example, REVNO[6:4] refers to bits 6–4 that are part of the COREREV field that
occupies bits 6–0 of the REVNO register.
• A continuous range of individual signals of a bus
For example, XAD[7:0] refers to signals 7–0 of the XAD bus.
1.5.3 Special terms
The following terms have special meanings:
Term
Meaning
asserted
Refers to the state of a signal as follows:
• An active-high signal is asserted when high (1).
• An active-low signal is asserted when low (0).
deasserted
Refers to the state of a signal as follows:
• An active-high signal is deasserted when low (0).
• An active-low signal is deasserted when high (1).
In some cases, deasserted signals are described as negated.
reserved
Refers to a memory space, register, field, or programming setting. Writes to a reserved location can
result in unpredictable functionality or behavior.
• Do not modify the default value of a reserved programming setting, such as the reset value of
a reserved register field.
• Consider undefined locations in memory to be reserved.
w1c
Write 1 to clear: Refers to a register bitfield that must be written as 1 to be "cleared."
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References
1.6 References
This addendum must be used in conjunction with the latest version of the MPC5777C
Reference Manual (document number MPC5777CRM).
In addition, the following documents provide information about the operation of the
MPC5777C:
• MPC5777C Data Sheet (document number MPC5777C)
• e200z759n3 Core Reference Manual (document number e200z759n3CRM),
available at www.freescale.com
• Safety Manual for MPC5777C (document number MPC5777CSM)
• IEEE-ISTO 5001-2003 Standard for a Global Embedded Processor Interface (Nexus)
• IEEE 1149.1-2001 standard - IEEE Standard Test Access Port and Boundary-Scan
Architecture
• Power Architecture Book E V1.0, available at www.freescale.com: http://
www.freescale.com/files/32bit/doc/user_guide/BOOK_EUM.pdf
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Chapter 2
Platform Configuration Module (PCM)
2.1 PCM memory map and register descriptions
The Platform Configuration Module contains three miscellaneous configuration registers
for the chip. Currently, the configuration registers are related to the operation of the FEC
and intelligent bus bridging gasket. The module is mapped to AIPS_0 (PBRIDGE_B) onplatform slot 27 with a base address of FFF6_C000h.
NOTE
These registers can be accessed only in supervisor mode.
PCM memory map
Address
offset (hex)
Register name
Width
Access
(in bits)
Reset value
Section/
page
0
FEC Burst Optimization Master Control Register
(PCM_FBOMCR)
32
R/W
0000_0000h
2.1.1/12
4
Bus Bridge Configuration Register 1 (PCM_IAHB_BE1)
32
R/W
0707_0707h
2.1.2/13
8
Bus Bridge Configuration Register 2 (PCM_IAHB_BE2)
32
R/W
0707_0707h
2.1.3/16
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PCM memory map and register descriptions
2.1.1 FEC Burst Optimization Master Control Register
(PCM_FBOMCR)
This register controls FEC burst optimization behavior on the system bus.
Address: 0h base + 0h offset = 0h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
R
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
ACCERR
WBEN
W
RBEN
0
0
0
0
0
0
0
R
W
Reset
0
0
0
0
0
FXSBE[7:0]
0
0
0
0
0
PCM_FBOMCR field descriptions
Field
Description
0–20
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
21
ACCERR
Accumulate Error
This field determines whether an error response for the first half of the write burst is accumulated to the
second half of the write burst or discarded. To complete the burst, the FEC interface to the system bus
responds by indicating that the first half of the burst completed without error before it actually writes the
data so that it can fetch the second half of the write data from the FIFO. When actually written onto the
system bus, the first half of the write burst can have an error. Because this half initially responded without
an error to the FIFO, the error is discarded or accumulated with the error response for the second half of
the burst.
0
1
Any error to the first half of the write burst is discarded.
Any actual error response to the first half of the write burst is accumulated in the second half's
response. In other words, an error response to the first half is seen in the response to the second half,
even if the second half does not contain an error.
22
WBEN
Global write burst enable to XBAR slave port designated by FXSBEn
23
RBEN
Global read burst enable from XBAR slave port designated by FXSBEn
0
1
0
1
Write bursting to all XBAR slave ports is disabled.
Write bursting is enabled to any XBAR slave port whose FXSBEn bit is 1.
Read bursting from all XBAR slave ports is disabled.
Read bursting is enabled from any XBAR slave port whose FXSBEn bit is 1.
Table continues on the next page...
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Chapter 2 Platform Configuration Module (PCM)
PCM_FBOMCR field descriptions (continued)
Field
Description
24–31
FXSBE[7:0]
FEC XBAR slave burst enable
This field enables bursting by the FEC interface to the XBAR slave port controlled by each FXSBEn bit.
• When a particular FXSBEn bit is 1, the XBAR slave port enabled by that bit can support the bursts
allowed by RBEN and WBEN. RBEN enables read bursts from the XBAR slave port, and WBEN
enables write bursts to the XBAR slave port.
• When a particular FXSBEn bit is 0, the FEC interface does not burst to the XBAR slave port
controlled by that FXSBEn bit.
FXSBEn assignments to XBAR slave ports are as follows:
FXSBE0 = Flash memory
FXSBE1 = EBI
FXSBE2 = RAM
FXSBE3 = reserved
FXSBE4 = reserved
FXSBE5 = reserved
FXSBE6 = AIPS_1 (PBRIDGE_A)
FXSBE7 = AIPS_0 (PBRIDGE_B)
2.1.2 Bus Bridge Configuration Register 1 (PCM_IAHB_BE1)
Address: 0h base + 4h offset = 4h
11
12
13
14
15
BWE_CORE1_
I
10
Reset
0
0
0
0
0
1
1
1
0
0
0
0
0
1
1
1
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
BWE_CORE0_
I
9
BRE_CORE1_I
8
BRE_CORE0_I
7
PRE_CORE1_I
6
PRE_CORE0_I
5
BWE_CORE1_
D
4
BWE_CORE0_
D
3
BRE_CORE1_
D
2
BRE_CORE0_
D
1
PRE_CORE1_
D
0
PRE_CORE0_
D
Bit
1
1
1
0
0
1
1
1
0
R
W
0
R
W
Reset
0
0
0
0
0
0
0
0
0
0
PCM_IAHB_BE1 field descriptions
Field
0–4
Reserved
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Table continues on the next page...
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PCM memory map and register descriptions
PCM_IAHB_BE1 field descriptions (continued)
Field
Description
5
Pending Read Enable Core1 Data
PRE_CORE1_D
This bit controls the bus gasket’s handling of pending read transactions.
0
1
Pending reads are disabled.
Pending reads are enabled.
6
Burst Read Enable Core1 Data
BRE_CORE1_D
This bit controls the bus gasket’s handling of burst read transactions.
0
1
Burst reads are converted into a series of single transactions on the slave side of the gasket.
Burst reads are optimized for best system performance.
7
Burst Write Enable Core1 Data
BWE_CORE1_D
This bit controls the bus gasket’s handling of burst write transactions.
0
1
8–12
Reserved
13
PRE_CORE1_I
This field is reserved.
This read-only field is reserved and always has the value 0.
Pending Read Enable Core1 Instruction
This bit controls the bus gasket’s handling of pending read transactions.
0
1
14
BRE_CORE1_I
Burst writes are converted into a series of single transactions on the slave side of the gasket.
Burst writes are optimized for best system performance. Note this setting treats writes as “imprecise”
such that an error response on any beat of the burst is reported on the last beat.
Pending reads are disabled.
Pending reads are enabled.
Burst Read Enable Core1 Instruction
This bit controls the bus gasket’s handling of burst read transactions.
0
1
Burst reads are converted into a series of single transactions on the slave side of the gasket.
Burst reads are optimized for best system performance.
15
Burst Write Enable Core1 Instruction
BWE_CORE1_I
This bit controls the bus gasket’s handling of burst write transactions.
0
1
16–20
Reserved
Burst writes are converted into a series of single transactions on the slave side of the gasket.
Burst writes are optimized for best system performance. Note this setting treats writes as “imprecise”
such that an error response on any beat of the burst is reported on the last beat.
This field is reserved.
This read-only field is reserved and always has the value 0.
21
Pending Read Enable Core0 Data
PRE_CORE0_D
This bit controls the bus gasket’s handling of pending read transactions.
0
1
Pending reads are disabled
Pending reads are enabled.
22
Burst Read Enable Core0 Data
BRE_CORE0_D
This bit controls the bus gasket’s handling of burst read transactions.
Table continues on the next page...
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Chapter 2 Platform Configuration Module (PCM)
PCM_IAHB_BE1 field descriptions (continued)
Field
Description
0
1
Burst reads are converted into a series of single transactions on the slave side of the gasket.
Burst reads are optimized for best system performance.
23
Burst Write Enable Core0 Data
BWE_CORE0_D
This bit controls the bus gasket’s handling of burst write transactions.
0
1
24–28
Reserved
29
PRE_CORE0_I
This field is reserved.
This read-only field is reserved and always has the value 0.
Pending Read Enable Core0 Instruction
This bit controls the bus gasket’s handling of pending read transactions.
0
1
30
BRE_CORE0_I
Burst writes are converted into a series of single transactions on the slave side of the gasket.
Burst writes are optimized for best system performance. Note this setting treats writes as “imprecise”
such that an error response on any beat of the burst is reported on the last beat.
Pending reads are disabled.
Pending reads are enabled.
Burst Read Enable Core0 Instruction
This bit controls the bus gasket’s handling of burst read transactions.
0
1
Burst reads are converted into a series of single transactions on the slave side of the gasket.
Burst reads are optimized for best system performance.
31
Burst Write Enable Core0 Instruction
BWE_CORE0_I
This bit controls the bus gasket’s handling of burst write transactions.
0
1
Burst writes are converted into a series of single transactions on the slave side of the gasket.
Burst writes are optimized for best system performance. Note this setting treats writes as “imprecise”
such that an error response on any beat of the burst is reported on the last beat.
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PCM memory map and register descriptions
2.1.3 Bus Bridge Configuration Register 2 (PCM_IAHB_BE2)
Address: 0h base + 8h offset = 8h
0
1
2
3
4
5
6
0
8
9
10
11
12
13
14
15
PRE_
M6
0
BRE_M6
BWE_M6
Reset
0
0
0
0
0
1
1
1
0
0
0
0
0
1
1
1
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
PRE_DMA_B
BRE_DMA_B
BWE_DMA_B
PRE_DMA_A
BRE_DMA_A
BWE_DMA_A
R
7
BWE_FEC
Bit
1
1
1
0
0
1
1
1
PRE_ BRE_
FEC FEC
W
0
R
W
Reset
0
0
0
0
0
0
0
0
0
PCM_IAHB_BE2 field descriptions
Field
Description
0–4
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
5
PRE_FEC
Pending Read Enable FEC
This bit controls the bus gasket’s handling of pending read transactions.
0
1
6
BRE_FEC
Burst Read Enable FEC
This bit controls the bus gasket’s handling of burst read transactions.
0
1
7
BWE_FEC
Pending reads are disabled.
Pending reads are enabled.
Burst reads are converted into a series of single transactions on the slave side of the gasket.
Burst reads are optimized for best system performance.
Burst Write Enable FEC
This bit controls the bus gasket’s handling of burst write transactions.
0
1
Burst writes are converted into a series of single transactions on the slave side of the gasket.
Burst writes are optimized for best system performance. Note this setting treats writes as “imprecise”
such that an error response on any beat of the burst is reported on the last beat.
8–12
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
13
PRE_M6
Pending Read Enable Master Port 6 Concentrator
This bit controls the bus gasket’s handling of pending read transactions.
Table continues on the next page...
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Chapter 2 Platform Configuration Module (PCM)
PCM_IAHB_BE2 field descriptions (continued)
Field
Description
0
1
14
BRE_M6
Burst Read Enable Master Port 6 Concentrator
This bit controls the bus gasket’s handling of burst read transactions.
0
1
15
BWE_M6
21
PRE_DMA_B
This bit controls the bus gasket’s handling of burst write transactions.
Pending Read Enable eDMA_B
This bit controls the bus gasket’s handling of pending read transactions.
This bit controls the bus gasket’s handling of burst read transactions.
29
PRE_DMA_A
This bit controls the bus gasket’s handling of burst write transactions.
Burst writes are converted into a series of single transactions on the slave side of the gasket.
Burst writes are optimized for best system performance. Note this setting treats writes as “imprecise”
such that an error response on any beat of the burst is reported on the last beat.
This field is reserved.
This read-only field is reserved and always has the value 0.
Pending Read Enable eDMA_A
This bit controls the bus gasket’s handling of pending read transactions.
0
1
30
BRE_DMA_A
Burst reads are converted into a series of single transactions on the slave side of the gasket.
Burst reads are optimized for best system performance.
Burst Write Enable eDMA_B
0
1
24–28
Reserved
Pending reads are disabled
Pending reads are enabled.
Burst Read Enable eDMA_B
0
1
23
BWE_DMA_B
Burst writes are converted into a series of single transactions on the slave side of the gasket.
Burst writes are optimized for best system performance. Note this setting treats writes as “imprecise”
such that an error response on any beat of the burst is reported on the last beat.
This field is reserved.
This read-only field is reserved and always has the value 0.
0
1
22
BRE_DMA_B
Burst reads are converted into a series of single transactions on the slave side of the gasket.
Burst reads are optimized for best system performance.
Burst Write Enable Master Port 6 Concentrator
0
1
16–20
Reserved
Pending reads are disabled.
Pending reads are enabled.
Pending reads are disabled.
Pending reads are enabled.
Burst Read Enable eDMA_A
This bit controls the bus gasket’s handling of burst read transactions.
0
1
Burst reads are converted into a series of single transactions on the slave side of the gasket.
Burst reads are optimized for best system performance.
Table continues on the next page...
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PCM memory map and register descriptions
PCM_IAHB_BE2 field descriptions (continued)
Field
31
BWE_DMA_A
Description
Burst Write Enable eDMA_A
This bit controls the bus gasket’s handling of burst write transactions.
0
1
Burst writes are converted into a series of single transactions on the slave side of the gasket.
Burst writes are optimized for best system performance. Note this setting treats writes as “imprecise”
such that an error response on any beat of the burst is reported on the last beat.
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Chapter 3
Modular CAN (M_CAN)
3.1 Chip-specific M_CAN information
3.1.1 M_CAN Message RAM allocation
On this chip, each M_CAN instance can address 1216 words in the Message RAM.
As a result, the Message RAM shared by the two M_CAN instances supports 2432
words, or 9.5 KB.
3.1.2 Introduction
The M_CAN subsystem includes:
• Two M_CAN modules
• A Message RAM controller
The M_CAN subsystem block diagram is shown in the following figure.
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Chip-specific M_CAN information
M_CAN Subsystem
M _ C A N_0
host clock
CAN protocol clock
M_CAN_0_Rx
CPU reads/writes
M_CAN_0_Tx
External
Message
RAM
CPU clock*
CPU reads/writes
Message RAM
Controller
M _ C A N_1
host clock
M_CAN_1_Rx
CPU reads/writes
M_CAN_1_Tx
*Refer to the Clocking chapter for M_CAN clock details.
Figure 3-1. M_CAN subsystem block diagram
3.1.3 Functional Description
3.1.3.1 Message RAM Controller
The Message RAM Controller has the arbiter for the accesses to the external Message
RAM and the ECC (Error Code Correction) Controller for the external Message RAM
data.
3.1.3.1.1
Message RAM Arbiter
The Message RAM Arbiter is a dynamic round robin arbiter that selects which request is
sent to the external Message RAM. These requests are made by the CPU, M_CAN_0, or
M_CAN_1.
This arbiter ensures:
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Chapter 3 Modular CAN (M_CAN)
• 50% bandwidth for CPU accesses to the external Message RAM. The CPU does not
wait for more than one clock cycle to access the external Message RAM (see
examples 1 and 3).
• 50% bandwidth is shared between M_CAN_0 and M_CAN_1 accesses to the
external Message RAM. Each M_CAN waits at least one clock cycle to access the
external Message RAM (see examples 1, 2, and 3).
• If there is no CPU request, all bandwidth is distributed to M_CAN_0 and M_CAN_1
(see example 2).
• If there are no M_CAN_0 and M_CAN_1 requests, all bandwidth is distributed to the
CPU.
• If there are requests from only one M_CAN, the other M_CAN's bandwidth is
distributed to the first M_CAN (see example 1).
The following examples illustrate the dynamic arbiter scheme.
• Example 1: The following figure shows who accesses the external Message RAM
when only CPU and M_CAN_0 try to access to it.
CPU clock
who accesses the
external Message RAM
CPU
M_CAN_0
CPU
M_CAN_0
CPU
M_CAN_0
CPU
M_CAN_0
• Example 2: The following figure shows who accesses the external Message RAM
when only M_CAN_0 and M_CAN_1 try to access to it.
CPU clock
who accesses the
external Message RAM
M_CAN_0
M_CAN_1
M_CAN_0
M_CAN_1 M_CAN_0
M_CAN_1 M_CAN_0
M_CAN_1
• Example 3: The following figure shows who accesses the external Message RAM
when the CPU, M_CAN_0, and M_CAN_1 try to access to it.
CPU clock
who accesses the
external Message RAM
CPU
M_CAN_0
CPU
M_CAN_1
CPU
M_CAN_0
CPU
M_CAN_1
The read or write accesses to the external Message RAM use two clock cycles. In the first
clock cycle, the address is available, and in the second, the data is available.
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Chip-specific M_CAN information
The arbiter has a pseudo address pre-fetching mechanism that allows the data of the
previous access to overlap with the address of the current access. The pseudo address prefetching scheme saves multiple clock cycles when there are multiples accesses to the
external Message RAM.
3.1.3.1.2
ECC Controller
The ECC Controller provides Single Error Correction / Double Error Detection
(SECDED). It guarantees single bit error correction and double bit error detection
(without correction). The SECDED code is not guaranteed to detect more than two bits
with error.
Each 32 data bits of the external Message RAM is associated with 7 ECC bits. If all these
39 bits are zero or one, then it is flagged as non-correctable error.
For writes to the external Message RAM, the ECC bits (7-bit) are calculated using the
data bits (32-bit). The data bits plus ECC bits (39-bit) are written into the specified
memory address. The error detection and correction are performed on the reads from the
external Message RAM.
When an M_CAN accesses the external Message RAM, the ECC bits are calculated by
the ECC Controller and they are sent to this M_CAN.
3.1.3.2 External Message RAM
The external Message RAM supports only 32-bit write and read accesses.
The CPU can access the external Message RAM through the M_CAN subsystem. In this
case, the CPU can do 8/16/32-bit read accesses to the external Message RAM.
3.1.3.3 Transfer Error
The M_CAN subsystem does not report any transfer error.
3.1.4 External Signals
The M_CAN subsystem external signals are shown in the following table.
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Chapter 3 Modular CAN (M_CAN)
Table 3-1. M_CAN subsystem external signals
Signal name
Direction
Description
M_CAN_0_Rx
input
M_CAN_0 CAN Rx signal
M_CAN_0_Tx
output
M_CAN_0 CAN Tx signal
M_CAN_1_Rx
input
M_CAN_1 CAN Rx signal
M_CAN_1_Tx
output
M_CAN_1 CAN Tx signal
3.2 Overview
The M_CAN module is the new CAN Communication Controller IP-module. The
M_CAN performs communication according to ISO11898-1 (Bosch CAN specification
2.0 part A,B) and to Bosch CAN FD specification V1.0. Additional transceiver hardware
is required for connection to the physical layer.
The message storage is intended to be a single- or dual-ported Message RAM outside of
the module. It is connected to the M_CAN via the Generic Master Interface. Depending
on the chosen device, multiple M_CAN controllers can share the same Message RAM.
All functions concerning the handling of messages are implemented by the Rx Handler
and the Tx Handler. The Rx Handler manages message acceptance filtering, the transfer
of received messages from the CAN Core to the Message RAM as well as providing
receive message status information. The Tx Handler is responsible for the transfer of
transmit messages from the Message RAM to the CAN Core as well as providing
transmit status information.
Acceptance filtering is implemented by a combination of up to 128 filter elements where
each one can be configured as a range, as a bit mask, or as a dedicated ID filter.
The M_CAN can be connected to a wide range of Host CPUs via its 8/16/32-bit Generic
Slave Interface. The M_CAN's clock domain concept allows the separation between the
high precision CAN clock and the Host clock, which may be generated by an FM-PLL.
3.2.1 Features
The following are the features of M_CAN.
• Conforms with CAN protocol version 2.0 part A, B and ISO 11898-1
• CAN FD with up to 64 data bytes supported
• CAN Error Logging
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Overview
• AUTOSAR optimized
• SAE J1939 optimized
• Improved acceptance filtering
• Two configurable Receive FIFOs
• Separate signalling on reception of High Priority Messages
• Up to 64 dedicated Receive Buffers
• Up to 32 dedicated Transmit Buffers
• Configurable Transmit FIFO
• Configurable Transmit Queue
• Configurable Transmit Event FIFO
• Direct Message RAM access for Host CPU
• Multiple M_CANs may share the same Message RAM
• Programmable loop-back test mode
• Maskable module interrupts
• 8/16/32-bit Generic Slave Interface for connection customer-specific Host CPUs
• Two clock domains (CAN clock and Host clock)
• Power-down support
• Debug on CAN support
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Chapter 3 Modular CAN (M_CAN)
CAN Tx
CAN Rx
Sync
Cfg and Ctrl
Tx_State
Tx_Req
Tx Handler
Tx Prioritization
Rx_State
Cfg and Ctrl
Memory IF
Clk
32
Timestamp
8/16/32
Host IF
CAN Core
Generic Master IF
Generic Slave IF
M_CAN
Cfg and Ctrl
3.2.2 Block Diagram
Rx Handler
Acceptance Filter
CAN Clock Domain
Host Clock Domain
Figure 3-2. M_CAN Block Diagram
• CAN Core: CAN Protocol Controller and Rx/Tx Shift Register. Handles all ISO
11898-1 protocol functions. Supports 11-bit and 29-bit identifiers.
• Sync: Synchronizes signals from the Host clock domain to the CAN clock domain
and vice versa.
• Clk: Synchronizes reset signal to the Host clock domain and to the CAN clock
domain.
• Cfg and Ctrl: CAN Core related configuration and control bits.
• Interrupt and Timestamp: Interrupt control and 16-bit CAN bit time counter for
receive and transmit timestamp generation.
• Tx Handler: Controls the message transfer from the external Message RAM to the
CAN Core. A maximum of 32 Tx Buffers can be configured for transmission. Tx
buffers can be used as dedicated Tx Buffers, as Tx FIFO, part of a Tx Queue, or as a
combination of them. A Tx Event FIFO stores Tx timestamps together with the
corresponding Message ID. Transmit cancellation is also supported.
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Overview
• Rx Handler: Controls the transfer of received messages from the CAN Core to the
external Message RAM. The Rx Handler supports two Receive FIFOs, each of
configurable size, and up to 64 dedicated Rx Buffers for storage of all messages that
have passed acceptance filtering. A dedicated Rx Buffer, in contrast to a Receive
FIFO, is used to store only messages with a specific identifier. An Rx timestamp is
stored together with each message. Up to 128 filters can be defined for 11-bit IDs
and up to 64 filters for 29-bit IDs.
• Generic Slave Interface: Connects the M_CAN to a specific Host CPU. The Generic
Slave Interface is capable to connect to an 8/16/32-bit bus to support a wide range of
interconnection structures.
• Generic Master Interface: Connects the M_CAN access to an external 32-bit
Message RAM. The maximum Message RAM size is 16 KB × 32-bit.
• Extension Interface: All flags from the Interrupt Register IR as well as selected
internal status and control signals are routed to this interface. The interface is
intended for connection of the M_CAN to a module-external interrupt unit or other
module-external components. The connection of these signals is optional.
3.2.3 Dual Clock Sources
To improve the EMC behavior, a spread spectrum clock can be used for the Host clock
domain. Due to the high precision clocking requirements of the CAN Core, a separate
clock without any modulation has to be provided as CAN clock.
Within the M_CAN module there is a synchronization mechanism implemented to ensure
save data transfer between the two clock domains.
Note
In order to achieve a stable function of the M_CAN, the Host
clock must always be faster than or equal to the CAN clock.
Also, the modulation depth of a spread spectrum clock must be
regarded.
3.2.4 Dual Interrupt Lines
The module provides two interrupt lines. Interrupts can be routed either to M_CAN
interrupt 0 or to M_CAN interrupt 1. By default all interrupts are routed to interrupt line
M_CAN interrupt 0. By programming ILE[EINT0] and ILE[EINT1], the interrupt lines
can be enabled or disabled separately.
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3.3 Memory Map and Register Description
After hardware reset, the registers of the M_CAN hold the reset values. Additionally the
Bus_Off state is reset and the M_CAN Tx is set to recessive (HIGH). The value 0x0001
(CCCR[INIT] = 1) in the CC Control Register enables software initialization. The
M_CAN does not influence the CAN bus until the CPU resets CCCR[INIT] to 0.
The M_CAN module allocates an address space of 256 bytes. All registers are organized
as 32-bit registers. The M_CAN is accessible by the CPU using a data width of 8-bit
(byte access), 16-bit (half-word access), or 32-bit (word access).
The CPU has write access to Protected Write registers and fields when both CCCR[CCE]
is 1 and CCCR[INIT] is 1.
There is a delay from writing to a command register until the update of the related status
register bits due to clock domain crossing.
CAUTION
Any write access to reserved or not implemented registers in
the slot assigned by to the M_CAN IP will not generate any bus
access error.
M_CAN memory map
Address
offset (hex)
Register name
Width
Access
(in bits)
Reset value
Section/
page
0
Core Release Register (M_CAN_CREL)
32
R
See section
3.3.1/28
4
Endian Register (M_CAN_ENDN)
32
R
8765_4321h
3.3.2/29
C
Fast Bit Timing and Prescaler Register (M_CAN_FBTP)
32
R/W
0000_0A33h
3.3.3/30
10
Test Register (M_CAN_TEST)
32
R/W
See section
3.3.4/32
14
RAM Watchdog Register (M_CAN_RWD)
32
R/W
0000_0000h
3.3.5/33
18
CC Control Register (M_CAN_CCCR)
32
R/W
0000_0001h
3.3.6/34
1C
Bit Timing and Prescaler Register (M_CAN_BTP)
32
R/W
0000_0A33h
3.3.7/36
20
Timestamp Counter Configuration Register (M_CAN_TSCC)
32
R/W
0000_0000h
3.3.8/38
24
Timestamp Counter Value Register (M_CAN_TSCV)
32
w1c
0000_0000h
3.3.9/38
28
Timeout Counter Configuration Register (M_CAN_TOCC)
32
R/W
FFFF_0000h
3.3.10/39
2C
Timeout Counter Value Register (M_CAN_TOCV)
32
w1c
0000_FFFFh
3.3.11/40
40
Error Counter Register (M_CAN_ECR)
32
R
0000_0000h
3.3.12/41
44
Protocol Status Register (M_CAN_PSR)
32
R
0000_0707h
3.3.13/42
50
Interrupt Register (M_CAN_IR)
32
w1c
0000_0000h
3.3.14/45
54
Interrupt Enable Register (M_CAN_IE)
32
R/W
0000_0000h
3.3.15/49
Table continues on the next page...
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Memory Map and Register Description
M_CAN memory map (continued)
Address
offset (hex)
Register name
Width
Access
(in bits)
Reset value
Section/
page
58
Interrupt Line Select Register (M_CAN_ILS)
32
R/W
0000_0000h
3.3.16/52
5C
Interrupt Line Enable Register (M_CAN_ILE)
32
R/W
0000_0000h
3.3.17/55
80
Global Filter Configuration Register (M_CAN_GFC)
32
R/W
0000_0000h
3.3.18/56
84
Standard ID Filter Configuration Register (M_CAN_SIDFC)
32
R/W
0000_0000h
3.3.19/57
88
Extended ID Filter Configuration Register (M_CAN_XIDFC)
32
R/W
0000_0000h
3.3.20/58
90
Extended ID and Mask Register (M_CAN_XIDAM)
32
R/W
1FFF_FFFFh
3.3.21/59
94
High Priority Message Status Register (M_CAN_HPMS)
32
R
0000_0000h
3.3.22/59
98
New Data 1 Register (M_CAN_NDAT1)
32
R/W
0000_0000h
3.3.23/60
9C
New Data 2 Register (M_CAN_NDAT2)
32
R/W
0000_0000h
3.3.24/61
A0
Rx FIFO 0 Configuration Register (M_CAN_RXF0C)
32
R/W
0000_0000h
3.3.25/61
A4
Rx FIFO 0 Status Register (M_CAN_RXF0S)
32
R
0000_0000h
3.3.26/62
A8
Rx FIFO 0 Acknowledge Register (M_CAN_RXF0A)
32
R/W
0000_0000h
3.3.27/63
AC
Rx Buffer Configuration Register (M_CAN_RXBC)
32
R/W
0000_0000h
3.3.28/64
B0
Rx FIFO 1 Configuration Register (M_CAN_RXF1C)
32
R/W
0000_0000h
3.3.29/64
B4
Rx FIFO 1 Status Register (M_CAN_RXF1S)
32
R
0000_0000h
3.3.30/65
B8
Rx FIFO 1 Acknowledge Register (M_CAN_RXF1A)
32
R/W
0000_0000h
3.3.31/66
BC
Rx Buffer / FIFO Element Size Configuration Register
(M_CAN_RXESC)
32
R/W
0000_0000h
3.3.32/67
C0
Tx Buffer Configuration Register (M_CAN_TXBC)
32
R/W
0000_0000h
3.3.33/69
C4
Tx FIFO/Queue Status Register (M_CAN_TXFQS)
32
R
0000_0000h
3.3.34/70
C8
Tx Buffer Element Size Configuration (M_CAN_TXESC)
32
R/W
0000_0000h
3.3.35/71
CC
Tx Buffer Request Pending Register (M_CAN_TXBRP)
32
R
0000_0000h
3.3.36/72
D0
Tx Buffer Add Request Register (M_CAN_TXBAR)
32
R/W
0000_0000h
3.3.37/73
D4
Tx Buffer Cancellation Request Register (M_CAN_TXBCR)
32
R/W
0000_0000h
3.3.38/73
D8
Tx Buffer Transmission Occurred Register
(M_CAN_TXBTO)
32
R
0000_0000h
3.3.39/74
DC
Tx Buffer Cancellation Finished Register (M_CAN_TXBCF)
32
R
0000_0000h
3.3.40/74
E0
Tx Buffer Transmission Interrupt Enable Register
(M_CAN_TXBTIE)
32
R/W
0000_0000h
3.3.41/75
E4
Tx Buffer Cancellation Finished Interrupt Enable Register
(M_CAN_TXBCIE)
32
R/W
0000_0000h
3.3.42/75
F0
Tx Event FIFO Configuration Register (M_CAN_TXEFC)
32
R/W
0000_0000h
3.3.43/76
F4
Tx Event FIFO Status Register (M_CAN_TXEFS)
32
R
0000_0000h
3.3.44/77
F8
Tx Event FIFO Acknowledge Register (M_CAN_TXEFA)
32
R/W
0000_0000h
3.3.45/78
3.3.1 Core Release Register (M_CAN_CREL)
The following table shows example field values for this register and explains how they
encode a particular M_CAN core release.
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Chapter 3 Modular CAN (M_CAN)
REL
STEP
SUBSTEP
YEAR
MON
DAY
Release
0
2
0
9
3
26
Revision 0.2.0, date 2009/03/26
Address: 0h base + 0h offset = 0h
Bit
0
1
2
3
4
REL
R
5
6
7
8
STEP
9
10
11
12
SUBSTEP
13
14
15
16
17
18
YEAR
19
20
21
22
23
24
25
26
MON
27
28
29
30
31
DAY
W
Reset
x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x* x*
* Notes:
• The coding of revisions depends on the module version used in the device.x = Undefined at reset.
M_CAN_CREL field descriptions
Field
Description
0–3
REL
Core Release
One digit, BCD-coded.
4–7
STEP
Step of Core Release
One digit, BCD-coded.
8–11
SUBSTEP
Sub-step of Core Release
One digit, BCD-coded.
12–15
YEAR
Time Stamp Year
16–23
MON
Time Stamp Month
24–31
DAY
Time Stamp Day
One digit, BCD-coded.
Two digits, BCD-coded.
Two digits, BCD-coded.
3.3.2 Endian Register (M_CAN_ENDN)
Address: 0h base + 4h offset = 4h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
1
0
0
0
0
1
1
0
0
1
0
0
0
0
1
ETV
R
W
Reset
1
0
0
0
0
1
1
1
0
1
1
0
0
1
0
1
0
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Memory Map and Register Description
M_CAN_ENDN field descriptions
Field
Description
0–31
ETV
Endianness Test Value
The endianness test value is 0x87654321.
3.3.3 Fast Bit Timing and Prescaler Register (M_CAN_FBTP)
The CAN bit time may be programed in the range of 4 to 25 time quanta. The CAN time
quantum may be programmed in the range of 1 to 32 M_CAN clock periods. tq = (FBRP
+ 1) M_CAN clock period.
FTSEG1 is the sum of Prop_Seg and Phase_Seg1. FTSEG2 is Phase_Seg2. Therefore the
length of the bit time is (programmed values) [FTSEG1 + FTSEG2 + 3] tq or (functional
values) [Sync_Seg + Prop_Seg + Phase_Seg1 + Phase_Seg2] tq.
The Information Processing Time (IPT) is zero, meaning the data for the next bit is
available at the first clock edge after the sample point.
NOTE
With a M_CAN clock of 8 MHz, the reset value of
0x00000A33 configures the M_CAN for a fast bit rate of 500
kbit/s.
The bit rate configured for the CAN FD data phase via FBTP
must be higher or equal to the bit rate configured for the
arbitration phase via BTP.
Address: 0h base + Ch offset = Ch
Bit
0
1
2
3
4
0
R
Reset
0
0
Bit
16
17
0
8
9
10
11
12
0
0
0
0
0
0
0
0
18
19
20
21
22
23
24
25
26
27
28
0
0
0
1
0
1
0
0
15
0
0
0
29
30
31
0
FTSEG2
0
14
FBRP
0
FTSEG1
13
0
TDC
0
0
0
7
0
W
Reset
6
TDCO
W
R
5
1
1
0
FSJW
0
1
1
M_CAN_FBTP field descriptions
Field
0–2
Reserved
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Table continues on the next page...
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M_CAN_FBTP field descriptions (continued)
Field
3–7
TDCO
Description
Transceiver Delay Compensation Offset
NOTE: This field has Protected Write status.
0x00–0x1F
8
TDC
Offset value defining the distance between the measured delay from M_CAN Tx to M_CAN
Rx and the secondary sample point. Valid values are 0 to 31 M_CAN clock periods
Transceiver Delay Compensation
NOTE: This field has Protected Write status.
0
1
9–10
Reserved
11–15
FBRP
Transceiver Delay Compensation disabled
Transceiver Delay Compensation enabled
This field is reserved.
This read-only field is reserved and always has the value 0.
Fast Baud Rate Prescaler
(0x000–0x1F)— The value by which the oscillator frequency is divided for generating the bit time quanta.
The bit time is built up from a multiple of this quanta. Valid values for the Baud Rate Prescaler are 0 to 31.
The actual interpretation by the hardware of this value is such that one more than the value programmed
here is used.
NOTE: This field has Protected Write status.
16–19
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
20–23
FTSEG1
Fast time segment before sample point
(0x1–0xF)— Valid values are 1 to 15. The actual interpretation by the hardware of this value is such that
one more than the programmed value is used.
NOTE: This field has Protected Write status.
24
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
25–27
FTSEG2
Fast time segment after sample point
(0x0–0x7)— Valid values are 0 to 7. The actual interpretation by the hardware of this value is such that
one more than the programmed value is used.
NOTE: This field has Protected Write status.
28–29
Reserved
30–31
FSJW
This field is reserved.
This read-only field is reserved and always has the value 0.
Fast (Re) Synchronization Jump Width
(0x0–0x3)— Valid values are 0 to 3. The actual interpretation by the hardware of this value is such that
one more than the value programmed here is used.
NOTE: This field has Protected Write status.
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Memory Map and Register Description
3.3.4 Test Register (M_CAN_TEST)
Write access to the Test Register has to be enabled by setting CCCR[TEST] to 1. All Test
Register functions are set to their reset values when CCCR[TEST] is reset.
Loopback mode and software control of M_CAN Tx are hardware test modes.
Programming of Tx other than 00 may disturb the message transfer on the CAN bus.
Address: 0h base + 10h offset = 10h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
R
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
TDCV
RX
0
LBCK
0
R
TX
W
Reset
0
0
0
0
0
0
0
0
u*
0
0
0
0
0
* Notes:
• u = Unaffected by reset.
M_CAN_TEST field descriptions
Field
0–17
Reserved
18–23
TDCV
24
RX
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Transceiver Delay Compensation Value
(0x00–0x3F)— Position of the secondary sample point, defined by the sum of the measured delay from
M_CAN Tx to M_CAN Rx and FBTP[TDCO]. Valid value are 0 to 63 M_CAN clock periods.
Receive Pin
Monitors the actual value of M_CAN Rx
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Chapter 3 Modular CAN (M_CAN)
M_CAN_TEST field descriptions (continued)
Field
Description
0
1
25–26
TX
The CAN bus is dominant (M_CAN Rx = 0)
The CAN bus is recessive (M_CAN Rx = 1)
Control of Transmit Pin
NOTE: This field has Protected Write status.
00
01
10
11
27
LBCK
Reset value, M_CAN Tx is controlled by the M_CAN, updated at the end of the CAN bit time
Sample Point can be monitored at M_CAN Tx
Dominant (0) level at M_CAN Tx
Recessive (1) at M_CAN Tx
Loopback mode
NOTE: This field has Protected Write status.
0
1
28–31
Reserved
Reset value, Loopback mode is disabled
Loopback mode is enabled (see Test Modes)
This field is reserved.
This read-only field is reserved and always has the value 0.
3.3.5 RAM Watchdog Register (M_CAN_RWD)
The RAM Watchdog monitors when the Message RAM output is available to M_CAN.
When the M_CAN requests a Message RAM access, M_CAN starts the Message RAM
Watchdog Counter with the value configured by the RWD[WDC]. The counter is
reloaded with RWD[WDC] when the M_CAN request to Message RAM is successful
completed. In case there is no response from the Message RAM until the counter has
counted down to zero, the counter stops and interrupt flag IR[WDI] is set.
Address: 0h base + 14h offset = 14h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
0
R
19
20
21
22
23
24
25
26
WDV
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
28
29
30
31
0
0
0
WDC
W
Reset
27
0
0
0
0
0
0
0
0
M_CAN_RWD field descriptions
Field
0–15
Reserved
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
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Memory Map and Register Description
M_CAN_RWD field descriptions (continued)
Field
Description
16–23
WDV
Watchdog Value
24–31
WDC
Watchdog Configuration
Actual Message RAM Watchdog Counter Value.
Start value of the Message RAM Watchdog Counter. With the reset value of 00 the counter is disabled.
NOTE: This field has Protected Write status.
3.3.6 CC Control Register (M_CAN_CCCR)
For details about setting and resetting of single bits see Software Initialization.
Address: 0h base + 18h offset = 18h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
R
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
R
0
MON
CSR
ASM
CCE
INIT
0
0
0
0
1
W
Reset
0
TXP
0
FDBS FDO
0
0
CMR
0
CME
0
0
TEST DAR
0
0
0
CSA
0
M_CAN_CCCR field descriptions
Field
0–16
Reserved
17
TXP
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Transmit Pause
If this bit is set, the M_CAN pauses for two CAN bit times before starting the next transmission after itself
has successfully transmitted a frame (see Tx Handling).
NOTE: This field has Protected Write status.
0
1
Transmit pause disabled
Transmit pause enabled
18
FDBS
CAN FD Bit Rate Switching
19
FDO
CAN FD Operation
0
1
This node transmits no frames with bit rate switching
This node transmits all frames (excluding remote frames) with bit rate switching
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Chapter 3 Modular CAN (M_CAN)
M_CAN_CCCR field descriptions (continued)
Field
Description
0
1
20–21
CMR
CAN Mode Request
A change of the CAN operation mode is requested by writing to this bit field. After change to the requested
operation mode the bit field is reset to 00 and the status flags FDBS and FDO are set accordingly. In case
the requested CAN operation mode is not enabled, the value written to CMR is retained until it is
overwritten by the next mode change request. In case CME = 01/10/11 a change to CAN operation
according to ISO 11898-1 is always possible. Default is CAN operation according to ISO11898-1.
00
01
10
11
22–23
CME
This node transmits all frames in CAN format according to ISO11898-1
This node transmits all frames (excluding remote frames) in CAN FD format
Unchanged
Request CAN FD operation
Request CAN FD operation with bit rate switching
Request CAN operation according ISO11898-1
CAN Mode Enable
NOTE: When CME = 00, received frames are strictly interpreted according to ISO11898-1, which leads
to the transmission of an error frame when receiving a CAN FD frame. In case CME = 01,
transmission of long CAN FD frames and reception of long and fast CAN FD frames is enabled.
With CME = 10/11, transmission and reception of long and fast CAN FD frames is enabled.
NOTE: This field has Protected Write status.
00
01
10
11
24
TEST
Test Mode Enable
Bit TEST can only be set by the CPU when both CCE and INIT are set to 1. The bit can be reset by the
CPU at any time.
0
1
25
DAR
CAN operation according to ISO11898-1 enabled
CAN FD operation enabled
CAN FD operation with bit rate switching enabled
CAN FD operation with bit rate switching enabled
Normal operation, register TEST holds reset values
Test Mode, write access to register TEST enabled
Disable Automatic Retransmission
NOTE: This field has Protected Write status.
0
1
26
MON
Bus Monitoring Mode
Bit MON can only be set by the CPU when both CCE and INIT are set to 1. The bit can be reset by the
CPU at any time.
0
1
27
CSR
Automatic retransmission of messages not transmitted successfully enabled
Automatic retransmission disabled
Bus Monitoring Mode is disabled
Bus Monitoring Mode is enabled
Clock Stop Request
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Memory Map and Register Description
M_CAN_CCCR field descriptions (continued)
Field
Description
0
1
No clock stop is requested
Clock stop requested. When clock stop is requested, first INIT and then CSA will be set after all
pending transfer requests have been completed and the CAN bus reached idle.
28
CSA
Clock Stop Acknowledge
29
ASM
Restricted Operation Mode
0
1
Bit ASM is only set by the CPU when both CCE and INIT are set to 1. The bit can be reset by the CPU at
any time.
0
1
30
CCE
No clock stop acknowledged
M_CAN may be set in power down by stopping M_CAN input clocks
Normal CAN operation
Restricted Operation Mode active
Configuration Change Enable
NOTE: This field has Protected Write status.
0
1
31
INIT
The CPU has no write access to the protected configuration registers
The CPU has write access to the protected configuration registers (while CCCR[INIT] = 1)
Initialization
NOTE: Due to the synchronization mechanism between the two clock domains, there may be a delay
until the value written to INIT can be read back. Therefore the programmer has to assure that the
previous value written to INIT has been accepted by reading INIT before setting INIT to a new
value.
0
1
Normal Operation
Initialization is started
3.3.7 Bit Timing and Prescaler Register (M_CAN_BTP)
The CAN bit time may be programed in the range of [4....81] time quanta. The CAN time
quantum may be programmed in the range of [1....1024] M_CAN clock periods. tq =
(BRP + 1) M_CAN clock period.
TSEG1 is the sum of Prop_Seg and Phase_Seg1. TSEG2 is Phase_Seg2.
Therefore the length of the bit time is (programmed values) [TSEG1 + TSEG2 + 3] tq or
(functional values) [Sync_Seg + Prop_Seg + Phase_Seg1 + Phase_Seg2] tq.
The Information Processing Time (IPT) is zero, meaning the data for the next bit is
available at the first clock edge after the sample point.
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Chapter 3 Modular CAN (M_CAN)
NOTE
With a CAN clock of 8 MHz, the reset value of 0x0000_0A33
configures the M_CAN for a bit rate of 500 kBit/s.
Address: 0h base + 1Ch offset = 1Ch
Bit
0
1
2
3
4
5
6
7
8
9
0
R
0
0
0
11
12
13
14
15
16
0
0
0
0
0
0
0
0
0
17
18
19
0
BRP
W
Reset
10
0
0
0
0
0
20
21
22
23
24
TSEG1
0
0
0
1
0
25
26
27
28
TSEG2
1
0
0
0
1
29
30
31
SJW
1
0
0
1
1
M_CAN_BTP field descriptions
Field
0–5
Reserved
6–15
BRP
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Baud Rate Prescaler
(0x000-0x3FF)— The value by which the oscillator frequency is divided for generating the bit time quanta.
The bit time is built up from a multiple of this quanta. Valid values for the Baud Rate Prescaler are 0 to
1023. The actual interpretation by the hardware of this value is such that one more than the value
programmed here is used.
NOTE: This field has Protected Write status.
16–17
Reserved
18–23
TSEG1
This field is reserved.
This read-only field is reserved and always has the value 0.
Time segment before sample point
(0x01-0x3F)— Valid values are 1 to 63. The actual interpretation by the hardware of this value is such that
one more than the programmed value is used.
NOTE: This field has Protected Write status.
24–27
TSEG2
Time segment after sample point
(0x0-0xF)— Valid values are 0 to 15. The actual interpretation by the hardware of this value is such that
one more than the programmed value is used.
NOTE: This field has Protected Write status.
28–31
SJW
(Re) Synchronization Jump Width
(0x0-0xF)— Valid values are 0 to 15. The actual interpretation by the hardware of this value is such that
one more than the value programmed here is used.
NOTE: This field has Protected Write status.
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Memory Map and Register Description
3.3.8 Timestamp Counter Configuration Register (M_CAN_TSCC)
For a description of the Timestamp Counter see Timestamp Generation
Address: 0h base + 20h offset = 20h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
0
R
0
0
0
0
0
0
14
15
16
17
18
19
20
21
22
0
0
0
0
0
0
0
0
0
23
24
25
26
27
28
29
0
TCP
W
Reset
13
0
0
0
0
0
0
0
0
30
31
TSS
0
0
0
0
0
0
0
0
0
M_CAN_TSCC field descriptions
Field
Description
0–11
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
12–15
TCP
Timestamp Counter Prescaler
(0x0-0xF)— Configures the timestamp and timeout counters time unit in multiples of CAN bit times [1…
16]. The actual interpretation by the hardware of this value is such that one more than the value
programmed here is used.
NOTE: This field has Protected Write status.
NOTE: With CAN FD, timestamp generation is not supported.
16–29
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
30–31
TSS
Timestamp Select
NOTE: This field has Protected Write status.
00
01
10
11
Timestamp counter value always 0x0000
Timestamp counter value incremented according to TCP
Reserved
Same as 00
3.3.9 Timestamp Counter Value Register (M_CAN_TSCV)
Address: 0h base + 24h offset = 24h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
0
R
24
25
26
27
28
29
30
31
0
0
0
0
0
0
0
TSC
w1c
W
Reset
23
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
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Chapter 3 Modular CAN (M_CAN)
M_CAN_TSCV field descriptions
Field
Description
0–15
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
16–31
TSC
Timestamp Counter
The internal Timestamp Counter value is captured on start of frame (both Rx and Tx). When TSCC[TSS] =
01, the Timestamp Counter is incremented in multiples of CAN bit times [1…16] depending on the
configuration of TSCC[TCP]. A wrap around sets interrupt flag IR[TSW]. Write access resets the counter
to zero.
NOTE: A "wrap around" is a change of the Timestamp Counter value from non-zero to zero not caused
by write access to TSCV.
3.3.10 Timeout Counter Configuration Register (M_CAN_TOCC)
See Timeout Counter for a description of the Timeout Counter or for use of timeout
function with CAN FD.
Address: 0h base + 28h offset = 28h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
R
TOP
W
Reset
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
ETOC
0
R
TOS
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_TOCC field descriptions
Field
0–15
TOP
Description
Timeout Period
Start value of the Timeout Counter (down-counter). Configures the Timeout Period.
NOTE: This field has Protected Write status.
16–28
Reserved
29–30
TOS
This field is reserved.
This read-only field is reserved and always has the value 0.
Timeout Select
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Memory Map and Register Description
M_CAN_TOCC field descriptions (continued)
Field
Description
When operating in Continuous mode, a write to TOCV presets the counter to the value configured by
TOCC[TOP] and continues down-counting. When the Timeout Counter is controlled by one of the FIFOs,
an empty FIFO presets the counter to the value configured by TOCC[TOP]. Down-counting is started
when the first FIFO element is stored.
NOTE: This field has Protected Write status.
00
01
10
11
31
ETOC
Continuous operation
Timeout controlled by Tx Event FIFO
Timeout controlled by Rx FIFO 0
Timeout controlled by Rx FIFO 1
Enable Timeout Counte
NOTE: This field has Protected Write status.
0
1
Timeout Counter disabled
Timeout Counter enabled
3.3.11 Timeout Counter Value Register (M_CAN_TOCV)
Address: 0h base + 2Ch offset = 2Ch
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
0
R
24
25
26
27
28
29
30
31
1
1
1
1
1
1
1
TOC
w1c
W
Reset
23
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
M_CAN_TOCV field descriptions
Field
0–15
Reserved
16–31
TOC
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Timeout Counter
The Timeout Counter is decremented in multiples of CAN bit times [1…16] depending on the configuration
of TSCC[TCP]. When decremented to zero, interrupt flag IR[TOO] is set and the Timeout Counter is
stopped. Start and reset/restart conditions are configured via TOCC[TOS].
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Chapter 3 Modular CAN (M_CAN)
3.3.12 Error Counter Register (M_CAN_ECR)
NOTE
When CCCR[ASM] is set, the CAN protocol controller does
not increment TEC and REC when a CAN protocol error is
detected, but CEL is still incremented.
Address: 0h base + 40h offset = 40h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
0
R
12
13
14
15
CEL
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
R
RP
0
0
0
0
REC
TEC
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_ECR field descriptions
Field
0–7
Reserved
8–15
CEL
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
CAN Error Logging
The counter is incremented each time when a CAN protocol error causes the Transmit Error Counter or
the Receive Error Counter to be incremented. It is reset by read access to CEL. The counter stops at
0xFF; the next increment of TEC or REC sets interrupt flag IR[ELO].
16
RP
Receive Error Passive
17–23
REC
Receive Error Counter
24–31
TEC
Transmit Error Counter
0
1
The Receive Error Counter is below the error passive level of 128
The Receive Error Counter has reached the error passive level of 128
Actual state of the Receive Error Counter, values between 0 and 127.
Actual state of the Transmit Error Counter, values between 0 and 255.
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Memory Map and Register Description
3.3.13 Protocol Status Register (M_CAN_PSR)
NOTE
When a frame in CAN FD format has reached the data phase
with BRS flag set, the next CAN event (error or valid frame)
will be shown in FLEC instead of LEC. An error in a fixed stuff
bit of a CAN FD CRC sequence will be shown as a Form Error,
not Stuff Error.
NOTE
The Bus_Off recovery sequence (see CAN Specification Rev.
2.0 or ISO11898-1) cannot be shortened by setting or resetting
CCCR[INIT]. If the device goes Bus_Off, it will set
CCCR[INIT] of its own accord, stopping all bus activities.
Once CCCR[INIT] has been cleared by the CPU, the device
will then wait for 129 occurrences of Bus Idle (129 x 11
consecutive recessive bits) before resuming normal operation.
At the end of the Bus_Off recovery sequence, the Error
Management Counters will be reset. During the waiting time
after the resetting of CCCR[INIT], each time a sequence of 11
recessive bits has been monitored, a Bit0Error code is written to
PSR[LEC], enabling the CPU to readily check up whether the
CAN bus is stuck at dominant or continuously disturbed and to
monitor the Bus_Off recovery sequence. ECR[REC] is used to
count these sequences.
Address: 0h base + 44h offset = 44h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
R
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
BO
EW
EP
0
0
0
0
R
REDL RBRS RESI
FLEC
ACT
LEC
W
Reset
0
0
0
0
0
1
1
1
0
0
1
1
1
M_CAN_PSR field descriptions
Field
0–17
Reserved
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
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Chapter 3 Modular CAN (M_CAN)
M_CAN_PSR field descriptions (continued)
Field
18
REDL
Description
Received a CAN FD Message
This bit is set independent of acceptance filtering.
NOTE: This field is reset by a read operation.
0
1
19
RBRS
Since this bit was reset by the CPU, no CAN FD message has been received
Message in CAN FD format with EDL flag set has been received
BRS flag of last received CAN FD Message
This bit is set together with REDL, independent of acceptance filtering.
NOTE: This field is reset by a read operation.
0
1
20
RESI
Last received CAN FD message did not have its BRS flag set
Last received CAN FD message had its BRS flag set
ESI flag of last received CAN FD Message
This bit is set together with REDL, independent of acceptance filtering.
NOTE: This field is reset by a read operation.
0
1
21–23
FLEC
Last received CAN FD message did not have its ESI flag set
Last received CAN FD message had its ESI flag set
Fast Last Error Code
Type of last error that occurred in the data phase of a CAN FD format frame with its BRS flag set. Coding
is the same as for LEC. This field will be cleared to zero when a CAN FD format frame with its BRS flag
set has been transferred (reception or transmission) without error.
NOTE: This field is set by a read operation.
24
BO
Bus_Off Status
25
EW
Warning Status
26
EP
Error Passive
0
1
0
1
0
1
27–28
ACT
The M_CAN is not Bus_Off
The M_CAN is in Bus_Off state
Both error counters are below the Error_Warning limit of 96
At least one of error counter has reached the Error_Warning limit of 96
The M_CAN is in the Error_Active state. It normally takes part in bus communication and sends an
active error flag when an error has been detected
The M_CAN is in the Error_Passive state
Activity
Monitors the module's CAN communication state.
00
01
10
11
Synchronizing - node is synchronizing on CAN communication
Idle - node is neither receiver nor transmitter
Receiver - node is operating as receiver
Transmitter - node is operating as transmitter
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Memory Map and Register Description
M_CAN_PSR field descriptions (continued)
Field
29–31
LEC
Description
Last Error Code
The LEC indicates the type of the last error to occur on the CAN bus. This field will be cleared to 0 when a
message has been transferred (reception or transmission) without error.
NOTE: This field is set by a read operation.
000
001
010
011
100
101
110
111
Error: No error occurred since LEC has been reset by successful reception or transmission
Stuff Error: More than 5 equal bits in a sequence have occurred in a part of a received message
where this is not allowed
Form Error: A fixed format part of a received frame has the wrong format
AckError: The message transmitted by the M_CAN was not acknowledged by another node
Bit1Error: During the transmission of a message (with the exception of the arbitration field), the
device wanted to send a recessive level (bit of logical value 1), but the monitored bus value was
dominant
Bit0Error: During the transmission of a message (or acknowledge bit, or active error flag, or
overload flag), the device wanted to send a dominant level (data or identifier bit logical value 0), but
the monitored bus value was recessive. During Bus_Off recovery this status is set each time a
sequence of 11 recessive bits has been monitored. This enables the CPU to monitor the proceeding
of the Bus_Off recovery sequence (indicating the bus is not stuck at dominant or continuously
disturbed)
CRCError: The CRC check sum of a received message was incorrect. The CRC of an incoming
message does not match with the CRC calculated from the received data
NoChange: Any read access to the Protocol Status Register re-initializes the LEC to 7. When the
LEC shows the value 7, no CAN bus event was detected since the last CPU read access to the
Protocol Status Register
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Chapter 3 Modular CAN (M_CAN)
3.3.14 Interrupt Register (M_CAN_IR)
The flags are set when one of the listed conditions is detected (edge-sensitive). The flags
remain set until the CPU clears them. A flag is cleared by writing a 1 to the
corresponding bit position. Writing a 0 has no effect. A hard reset will clear the register.
The configuration of IE controls whether an interrupt is generated. The configuration of
ILS controls on which interrupt line an interrupt is signaled.
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
R
TFE
TCF
RF0L
RF0F
RF0W
RF0N
BEU
BEC
TSW
Reset
RF1N
ELO
MRAF
w1c
RF1W
11
TOO
w1c
RF1F
10
DRX
W
RF1L
9
EP
FOE
HPM
8
EW
STE
TC
7
BO
R
TEFN
6
WDI
2
TEFW
5
CRCE
1
TEFF
4
BE
0
W
w1c
w1c
w1c
w1c
w1c
w1c
w1c
w1c
w1c
w1c
w1c
w1c
w1c
w1c
w1c
w1c
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Reset
3
ACKE
Bit
TEFL
Address: 0h base + 50h offset = 50h
w1c
w1c
w1c
w1c
w1c
12
13
14
15
w1c
w1c
w1c
w1c
w1c
w1c
w1c
w1c
w1c
0
0
0
0
0
0
0
0
0
23
24
25
26
27
28
29
30
31
M_CAN_IR field descriptions
Field
Description
0
STE
Stuff Error
1
FOE
Format Error
2
ACKE
3
BE
0
1
0
1
No Stuff Error detected
More than 5 equal bits in a sequence occurred
No Format Error detected
A fixed format part of a received frame has the wrong format
Acknowledge Error
0
1
No Acknowledge Error detected
A transmitted message was not acknowledged by another node
Bit Error
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Memory Map and Register Description
M_CAN_IR field descriptions (continued)
Field
Description
0
1
4
CRCE
No Bit Error detected
Device wanted to send a rec / dom level, but monitored bus level was dom / rec
CRC Error
0
1
No CRC Error detected
Received CRC did not match the calculated CRC
5
WDI
Watchdog Interrupt
6
BO
Bus_Off Status
7
EW
Warning Status
8
EP
Error Passive
0
1
0
1
0
1
0
1
No Message RAM Watchdog event occurred
Message RAM Watchdog event due to missing READY
Bus_Off status unchanged
Bus_Off status changed
Error_Warning status unchanged
Error_Warning status changed
Error_Passive status unchanged
Error_Passive status changed
9
ELO
Error Logging Overflow
10
BEU
Bit Error Uncorrected
0
1
Message RAM bit error detected, uncorrected. Controlled by an external ECC logic attached to the
Message RAM. An uncorrected Message RAM bit error sets CCCR[INIT] to 1. This is done to avoid
transmission of corrupted data.
0
1
11
BEC
Message RAM bit error detected and corrected. Controlled by an external parity ECC logic attached to the
Message RAM.
No bit error detected when reading from Message RAM
Bit error detected and corrected (e.g. ECC)
Message stored to Dedicated Rx Buffer
The flag is set whenever a received message has been stored into a dedicated Rx Buffer.
0
1
13
TOO
No bit error detected when reading from Message RAM
Bit error detected, uncorrected (e.g. parity logic)
Bit Error Corrected
0
1
12
DRX
CAN Error Logging Counter did not overflow
Overflow of CAN Error Logging Counter occurred
No Rx Buffer updated
At least one received message stored into a Rx Buffer
Timeout Occurred
0
1
No timeout
Timeout reached
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Chapter 3 Modular CAN (M_CAN)
M_CAN_IR field descriptions (continued)
Field
14
MRAF
Description
Message RAM Access Failure
The flag is set, when the Rx Handler
• has not completed acceptance filtering or storage of an accepted message until the arbitration field
of the following message has been received. In this case acceptance filtering or message storage is
aborted and the Rx Handler starts processing of the following message.
• was not able to write a message to the Message RAM. In this case message storage is aborted.
In both cases the FIFO put index is not updated resp. the New Data flag for a dedicated Rx Buffer is not
set, a partly stored message is overwritten when the next message is stored to this location.
The flag is also set when the Tx Handler was not able to read a message from the Message RAM in time.
In this case message transmission is aborted. In case of a Tx Handler access failure the M_CAN is
switched into Restricted Operation Mode (see Restricted Operation Mode). To leave Restricted Operation
Mode, the CPU has to reset CCCR[ASM].
0
1
No Message RAM access failure occurred
Message RAM access failure occurred
15
TSW
Timestamp Wraparound
16
TEFL
Tx Event FIFO Element Lost
17
TEFF
Tx Event FIFO Full
18
TEFW
Tx Event FIFO Watermark Reached
19
TEFN
Tx Event FIFO New Entry
0
1
0
1
0
1
0
1
0
1
No timestamp counter wrap-around
Timestamp counter wrapped around
No Tx Event FIFO element lost
Tx Event FIFO element lost, also set after write attempt to Tx Event FIFO of size zero
Tx Event FIFO not full
Tx Event FIFO full
Tx Event FIFO fill level below watermark
Tx Event FIFO fill level reached watermark
Tx Event FIFO unchanged
Tx Handler wrote Tx Event FIFO element
20
TFE
Tx FIFO Empty
21
TCF
Transmission Cancellation Finished
22
TC
0
1
0
1
Tx FIFO non-empty
Tx FIFO empty
No transmission cancellation finished
Transmission cancellation finished
Transmission Completed
0
1
No transmission completed
Transmission completed
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Memory Map and Register Description
M_CAN_IR field descriptions (continued)
Field
Description
23
HPM
High Priority Message
24
RF1L
Rx FIFO 1 Message Lost
25
RF1F
Rx FIFO 1 Full
26
RF1W
Rx FIFO 1 Watermark Reached
27
RF1N
Rx FIFO 1 New Message
28
RF0L
Rx FIFO 0 Message Lost
29
RF0F
Rx FIFO 0 Full
30
RF0W
Rx FIFO 0 Watermark Reached
31
RF0N
Rx FIFO 0 New Message
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
No high priority message received
High priority message received
No Rx FIFO 1 message lost
Rx FIFO 1 message lost, also set after write attempt to Rx FIFO 1 of size zero
Rx FIFO 1 not full
Rx FIFO 1 full
Rx FIFO 1 fill level below watermark
Rx FIFO 1 fill level reached watermark
No new message written to Rx FIFO 1
New message written to Rx FIFO 1
No Rx FIFO 0 message lost
Rx FIFO 0 message lost, also set after write attempt to Rx FIFO 0 of size zero
Rx FIFO 0 not full
Rx FIFO 0 full
Rx FIFO 0 fill level below watermark
Rx FIFO 0 fill level reached watermark
No new message written to Rx FIFO 0
New message written to Rx FIFO 0
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Chapter 3 Modular CAN (M_CAN)
3.3.15 Interrupt Enable Register (M_CAN_IE)
The settings in the Interrupt Enable register determine which status changes in the
Interrupt Register will be signaled on an interrupt line.
Bit
0
1
BEE
MRAFE
TSWE
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
W
RF0WE
RF0NE
15
TOOE
14
RF0FE
13
RF0LE
12
RF1NE
11
RF1WE
10
RF1FE
9
RF1LE
8
HPME
7
TEFNE
6
ACKEE
5
TEFWE
4
TEFFE
3
TEFLE
R
2
CRCEE
Address: 0h base + 54h offset = 54h
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
STEE FOEE
W
R
WDIE BOE
TFEE TCFE TCE
0
0
0
EWE
EPE ELOE BEUE BECE DRXE
M_CAN_IE field descriptions
Field
Description
0
STEE
Stuff Error Interrupt Enable
1
FOEE
Format Error Interrupt Enable
2
ACKEE
3
BEE
0
1
0
1
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Acknowledge Error Interrupt Enable
0
1
Interrupt disabled
Interrupt enabled
Bit Error Interrupt Enable
0
1
Interrupt disabled
Interrupt enabled
4
CRCEE
CRC Error Interrupt Enable
5
WDIE
Watchdog Interrupt Enable
0
1
0
1
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
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Memory Map and Register Description
M_CAN_IE field descriptions (continued)
Field
Description
6
BOE
Bus_Off Status Interrupt Enable
7
EWE
Warning Status Interrupt Enable
8
EPE
Error Passive Interrupt Enable
0
1
0
1
0
1
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
9
ELOE
Error Logging Overflow Interrupt Enable
10
BEUE
Bit Error Uncorrected Interrupt Enable
11
BECE
Bit Error Corrected Interrupt Enable
12
DRXE
Message stored to Dedicated Rx Buffer Interrupt Enable
13
TOOE
Timeout Occurred Interrupt Enable
14
MRAFE
0
1
0
1
0
1
0
1
0
1
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Message RAM Access Failure Interrupt Enable
0
1
Interrupt disabled
Interrupt enabled
15
TSWE
Timestamp Wraparound Interrupt Enable
16
TEFLE
Tx Event FIFO Element Lost Interrupt Enable
17
TEFFE
Tx Event FIFO Full Interrupt Enable
0
1
0
1
0
1
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
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Chapter 3 Modular CAN (M_CAN)
M_CAN_IE field descriptions (continued)
Field
Description
18
TEFWE
Tx Event FIFO Watermark Reached Interrupt Enable
19
TEFNE
Tx Event FIFO New Entry Interrupt Enable
0
1
0
1
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
20
TFEE
Tx FIFO Empty Interrupt Enable
21
TCFE
Transmission Cancellation Finished Interrupt Enable
22
TCE
0
1
0
1
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Transmission Completed Interrupt Enable
0
1
Interrupt disabled
Interrupt enabled
23
HPME
High Priority Message Interrupt Enable
24
RF1LE
Rx FIFO 1 Message Lost Interrupt Enable
25
RF1FE
Rx FIFO 1 Full Interrupt Enable
26
RF1WE
Rx FIFO 1 Watermark Reached Interrupt Enable
27
RF1NE
Rx FIFO 1 New Message Interrupt Enable
28
RF0LE
Rx FIFO 0 Message Lost Interrupt Enable
29
RF0FE
Rx FIFO 0 Full Interrupt Enable
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
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Memory Map and Register Description
M_CAN_IE field descriptions (continued)
Field
Description
30
RF0WE
Rx FIFO 0 Watermark Reached Interrupt Enable
31
RF0NE
Rx FIFO 0 New Message Interrupt Enable
0
1
0
1
Interrupt disabled
Interrupt enabled
Interrupt disabled
Interrupt enabled
3.3.16 Interrupt Line Select Register (M_CAN_ILS)
The Interrupt Line Select register assigns an interrupt generated by a specific interrupt
flag from the Interrupt Register to one of the two module interrupt lines.
Address: 0h base + 58h offset = 58h
Bit
0
1
BEL
WDIL
TOOL
MRAFL
TSWL
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
TCL
W
RF0WL
RF0NL
15
RF0FL
14
RF0LL
13
RF1NL
12
RF1WL
EPL
11
RF1FL
EWL
10
RF1LL
BOL
9
HPML
8
CRCEL
7
TEFNL
6
ACKEL
5
TEFWL
4
TEFFL
3
TEFLL
R
2
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
STEL FOEL
W
R
TFEL TCFL
0
0
ELOL BEUL BECL DRXL
M_CAN_ILS field descriptions
Field
Description
0
STEL
Stuff Error Interrupt Line
1
FOEL
Format Error Interrupt Line
2
ACKEL
0
1
0
1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Acknowledge Error Interrupt Line
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Chapter 3 Modular CAN (M_CAN)
M_CAN_ILS field descriptions (continued)
Field
Description
0
1
3
BEL
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Bit Error Interrupt Line
0
1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
4
CRCEL
CRC Error Interrupt Line
5
WDIL
Watchdog Interrupt Line
6
BOL
Bus_Off Status Interrupt Line
7
EWL
Warning Status Interrupt Line
8
EPL
Error Passive Interrupt Line
0
1
0
1
0
1
0
1
0
1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
9
ELOL
Error Logging Overflow Interrupt Line
10
BEUL
Bit Error Uncorrected Interrupt Line
11
BECL
Bit Error Corrected Interrupt Line
12
DRXL
Message stored to Dedicated Rx Buffer Interrupt Line
13
TOOL
Timeout Occurred Interrupt Line
14
MRAFL
0
1
0
1
0
1
0
1
0
1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Message RAM Access Failure Interrupt Line
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Memory Map and Register Description
M_CAN_ILS field descriptions (continued)
Field
Description
0
1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
15
TSWL
Timestamp Wraparound Interrupt Line
16
TEFLL
Tx Event FIFO Element Lost Interrupt Line
17
TEFFL
Tx Event FIFO Full Interrupt Line
18
TEFWL
Tx Event FIFO Watermark Reached Interrupt Line
19
TEFNL
Tx Event FIFO New Entry Interrupt Line
0
1
0
1
0
1
0
1
0
1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
20
TFEL
Tx FIFO Empty Interrupt Line
21
TCFL
Transmission Cancellation Finished Interrupt Line
22
TCL
0
1
0
1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Transmission Completed Interrupt Line
0
1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
23
HPML
High Priority Message Interrupt Line
24
RF1LL
Rx FIFO 1 Message Lost Interrupt Line
25
RF1FL
Rx FIFO 1 Full Interrupt Line
26
RF1WL
Rx FIFO 1 Watermark Reached Interrupt Line
0
1
0
1
0
1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
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Chapter 3 Modular CAN (M_CAN)
M_CAN_ILS field descriptions (continued)
Field
Description
0
1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
27
RF1NL
Rx FIFO 1 New Message Interrupt Line
28
RF0LL
Rx FIFO 0 Message Lost Interrupt Line
29
RF0FL
Rx FIFO 0 Full Interrupt Line
30
RF0WL
Rx FIFO 0 Watermark Reached Interrupt Line
31
RF0NL
Rx FIFO 0 New Message Interrupt Line
0
1
0
1
0
1
0
1
0
1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
Interrupt assigned to M_CAN interrupt line 0
Interrupt assigned to M_CAN interrupt line 1
3.3.17 Interrupt Line Enable Register (M_CAN_ILE)
Each of the two interrupt lines to the CPU can be enabled / disabled separately by
programming bits EINT0 and EINT1.
Address: 0h base + 5Ch offset = 5Ch
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
R
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
EINT1
EINT0
W
0
0
0
0
0
0
0
0
0
0
R
W
Reset
0
0
0
0
0
0
0
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Memory Map and Register Description
M_CAN_ILE field descriptions
Field
Description
0–29
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
30
EINT1
Enable Interrupt Line 1
31
EINT0
Enable Interrupt Line 0
0
1
0
1
M_CAN interrupt line 1 disabled
M_CAN interrupt line 1 enabled
M_CAN interrupt line 0 disabled
M_CAN interrupt line 0 enabled
3.3.18 Global Filter Configuration Register (M_CAN_GFC)
Global settings for Message ID filtering. The Global Filter Configuration controls the
filter path for standard and extended messages as described in the Standard Message ID
Filtering and Extended Message ID Filtering.
Address: 0h base + 80h offset = 80h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
R
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
R
ANFS
W
Reset
0
0
0
0
0
0
0
0
0
0
0
ANFE
0
0
RRFS RRFE
0
0
0
M_CAN_GFC field descriptions
Field
0–25
Reserved
26–27
ANFS
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Accept Non-matching Frames Standard
Defines how received messages with 11-bit IDs that do not match any element of the filter list are treated.
NOTE: This field has Protected Write status.
00
01
10
11
Accept in Rx FIFO 0
Accept in Rx FIFO 1
Reject
Reject
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Chapter 3 Modular CAN (M_CAN)
M_CAN_GFC field descriptions (continued)
Field
Description
28–29
ANFE
Accept Non-matching Frames Extended
Defines how received messages with 29-bit IDs that do not match any element of the filter list are treated.
NOTE: This field has Protected Write status.
00
01
10
11
30
RRFS
Accept in Rx FIFO 0
Accept in Rx FIFO 1
Reject
Reject
Reject Remote Frames Standard
NOTE: This field has Protected Write status.
0
1
31
RRFE
Filter remote frames with 11-bit standard IDs
Reject all remote frames with 11-bit standard IDs
Reject Remote Frames Extended
NOTE: This field has Protected Write status.
0
1
Filter remote frames with 29-bit extended IDs
Reject all remote frames with 29-bit extended IDs
3.3.19 Standard ID Filter Configuration Register (M_CAN_SIDFC)
Settings for 11-bit standard Message ID filtering. The Standard ID Filter Configuration
controls the filter path for the standard messages as described in Standard Message ID
Filtering.
Address: 0h base + 84h offset = 84h
Bit
0
1
2
3
4
5
6
7
8
9
10
0
R
0
0
0
0
12
13
14
15
16
17
18
19
20
21
LSS
W
Reset
11
0
0
0
0
0
0
0
0
0
22
23
24
25
26
27
28
29
30
0
FLSSA
0
0
0
0
0
0
0
0
0
0
0
31
0
0
0
0
0
0
0
0
M_CAN_SIDFC field descriptions
Field
0–7
Reserved
8–15
LSS
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
List Size Standard
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Memory Map and Register Description
M_CAN_SIDFC field descriptions (continued)
Field
Description
NOTE: This field has Protected Write status.
0
1-128
>128
16–29
FLSSA
No standard Message ID filter
Number of standard Message ID filter elements
Values greater than 128 are interpreted as 128
Filter List Standard Start Address
Start address of standard Message ID filter list (32-bit word address, see Message RAM).
NOTE: This field has Protected Write status.
30–31
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
3.3.20 Extended ID Filter Configuration Register (M_CAN_XIDFC)
Settings for 29-bit extended Message ID filtering. The Extended ID Filter Configuration
controls the filter path for the standard messages as described in Extended Message ID
Filtering.
Address: 0h base + 88h offset = 88h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
0
R
0
0
0
0
0
13
14
15
16
17
18
19
20
21
LSE
W
Reset
12
0
0
0
0
0
0
0
0
22
23
24
25
26
27
28
29
30
0
FLESA
0
0
0
0
0
0
0
0
0
0
0
31
0
0
0
0
0
0
0
0
M_CAN_XIDFC field descriptions
Field
0–8
Reserved
9–15
LSE
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
List Size Extended
NOTE: This field has Protected Write status.
0
1-64
>64
16–29
FLESA
No extended Message ID filter
Number of extended Message ID filter elements
Values greater than 64 are interpreted as 64
Filter List Extended Start Address
Start address of extended Message ID filter list (32-bit word address, see Message RAM).
NOTE: This field has Protected Write status.
30–31
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
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3.3.21 Extended ID and Mask Register (M_CAN_XIDAM)
Address: 0h base + 90h offset = 90h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0
R
0
18
19
20
21
22
23
24
25
26
27
28
29
30
31
1
1
1
1
1
1
1
1
1
1
1
1
1
1
EIDM
W
Reset
17
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
M_CAN_XIDAM field descriptions
Field
Description
0–2
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
3–31
EIDM
Extended ID Mask
For acceptance filtering of extended frames the Extended ID and Mask is ANDed with the Message ID of a
received frame. Intended for masking of 29-bit IDs in SAE J1939. With the reset value of all bits set to one
the mask is not active.
NOTE: This field has Protected Write status.
3.3.22 High Priority Message Status Register (M_CAN_HPMS)
This register is updated every time a Message ID filter element configured to generate a
priority event matches. This can be used to monitor the status of incoming high priority
messages and to enable fast access to these messages.
Address: 0h base + 94h offset = 94h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
R
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
R
FLST
0
0
0
FIDX
MSI
BIDX
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_HPMS field descriptions
Field
0–15
Reserved
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
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Memory Map and Register Description
M_CAN_HPMS field descriptions (continued)
Field
Description
16
FLST
Filter List
Indicates the filter list of the matching filter element.
0
1
Standard Filter List
Extended Filter List
17–23
FIDX
Filter Index
24–25
MSI
Message Storage Indicator
26–31
BIDX
Buffer Index
Index of matching filter element. Range is 0 to SIDFC[LSS] - 1 resp. XIDFC[LSE] - 1.
00
01
10
11
No FIFO selected
FIFO message lost
Message stored in FIFO 0
Message stored in FIFO 1
Index of Rx FIFO element to which the message was stored. Only valid when MSI[1] = 1.
3.3.23 New Data 1 Register (M_CAN_NDAT1)
Address: 0h base + 98h offset = 98h
Bit
R
W
0
Reset
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
ND1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_NDAT1 field descriptions
Field
0–31
ND1
Description
New Data[0:31]
The register holds the New Data flags of Rx Buffers 0 to 31. The flags are set when the respective Rx
Buffer has been updated from a received frame. The flags remain set until the CPU clears them. A flag is
cleared by writing a 1 to the corresponding bit position. Writing a 0 has no effect. A hard reset will clear the
register.
0
1
Rx Buffer not updated
Rx Buffer updated from new message
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3.3.24 New Data 2 Register (M_CAN_NDAT2)
Address: 0h base + 9Ch offset = 9Ch
Bit
R
W
0
1
Reset
0
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
ND2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_NDAT2 field descriptions
Field
Description
0–31
ND2
New Data[32:63]
The register holds the New Data flags of Rx Buffers 32 to 63. The flags are set when the respective Rx
Buffer has been updated from a received frame. The flags remain set until the CPU clears them. A flag is
cleared by writing a 1 to the corresponding bit position. Writing a 0 has no effect. A hard reset will clear the
register.
0
1
Rx Buffer not updated
Rx Buffer updated from new message
3.3.25 Rx FIFO 0 Configuration Register (M_CAN_RXF0C)
Address: 0h base + A0h offset = A0h
R
W
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
F0OM
Bit
F0WM
F0S
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
R
F0SA
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_RXF0C field descriptions
Field
0
F0OM
Description
FIFO 0 Operation Mode
FIFO 0 can be operated in blocking or in overwrite mode (see Rx FIFOs).
NOTE: This field has Protected Write status.
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Memory Map and Register Description
M_CAN_RXF0C field descriptions (continued)
Field
Description
0
1
1–7
F0WM
FIFO 0 blocking mode
FIFO 0 overwrite mode
Rx FIFO 0 Watermark
NOTE: This field has Protected Write status.
0
1-64
>64
8
Reserved
Watermark interrupt disabled
Level for Rx FIFO 0 watermark interrupt (IR[RF0W])
Watermark interrupt disabled
This field is reserved.
This read-only field is reserved and always has the value 0.
9–15
F0S
Rx FIFO 0 Size
The Rx FIFO 0 elements are indexed from 0 to F0S-1.
NOTE: This field has Protected Write status.
0
1-64
>64
16–29
F0SA
No Rx FIFO 0
Number of Rx FIFO 0 elements
Values greater than 64 are interpreted as 64
Rx FIFO 0 Start Address
Start address of Rx FIFO 0 in Message RAM (32-bit word address, see Message RAM ).
NOTE: This field has Protected Write status.
30–31
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
3.3.26 Rx FIFO 0 Status Register (M_CAN_RXF0S)
Address: 0h base + A4h offset = A4h
Bit
0
1
2
3
4
5
0
R
6
7
RF0L
F0F
8
9
10
11
12
0
13
14
15
F0PI
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
0
R
F0GI
0
F0FL
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
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M_CAN_RXF0S field descriptions
Field
Description
0–5
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
6
RF0L
Rx FIFO 0 Message Lost
This bit is a copy of interrupt flag IR[RF0L]. When IR[RF0L] is reset, this bit is also reset.
NOTE: Overwriting the oldest message when RXF0C.F0OM = ‘1’ will not set this flag.
0
1
7
F0F
No Rx FIFO 0 message lost
Rx FIFO 0 message lost, also set after write attempt to Rx FIFO 0 of size zero
Rx FIFO 0 Full
0
1
8–9
Reserved
Rx FIFO 0 not full
Rx FIFO 0 full
This field is reserved.
This read-only field is reserved and always has the value 0.
10–15
F0PI
Rx FIFO 0 Put Index
Rx FIFO 0 write index pointer, range 0 to 63
16–17
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
18–23
F0GI
Rx FIFO 0 Get Index
Rx FIFO 0 read index pointer, range 0 to 63.
24
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
25–31
F0FL
Rx FIFO 0 Fill Level
Number of elements stored in Rx FIFO 0, range 0 to 64.
3.3.27 Rx FIFO 0 Acknowledge Register (M_CAN_RXF0A)
Address: 0h base + A8h offset = A8h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
0
R
0
0
0
0
0
0
0
0
0
0
0
0
0
29
30
31
0
0
F0AI
W
Reset
28
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_RXF0A field descriptions
Field
0–25
Reserved
26–31
F0AI
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Rx FIFO 0 Acknowledge Index
After the CPU has read a message or a sequence of messages from Rx FIFO 0 it has to write the buffer
index of the last element read from Rx FIFO 0 to F0AI. This will set the Rx FIFO 0 Get Index RXF0S[F0GI]
to F0AI + 1 and update the FIFO 0 Fill Level RXF0S[F0FL].
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Memory Map and Register Description
3.3.28 Rx Buffer Configuration Register (M_CAN_RXBC)
Address: 0h base + ACh offset = ACh
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
0
R
0
0
0
0
0
0
0
0
23
24
25
26
27
28
29
30
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
31
0
RBSA
W
Reset
22
0
0
0
0
0
0
0
0
M_CAN_RXBC field descriptions
Field
Description
0–15
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
16–29
RBSA
Rx Buffer Start Address
Configures the start address of the Rx Buffers section in the Message RAM (32-bit word address). Also
used to reference debug messages A, B, C.
NOTE: This field has Protected Write status.
30–31
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
3.3.29 Rx FIFO 1 Configuration Register (M_CAN_RXF1C)
Address: 0h base + B0h offset = B0h
R
W
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
F1OM
Bit
F1WM
F1S
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
R
F1SA
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_RXF1C field descriptions
Field
0
F1OM
Description
FIFO 1 Operation Mode
FIFO 1 can be operated in blocking or in overwrite mode (see Rx FIFOs).
NOTE: This field has Protected Write status.
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M_CAN_RXF1C field descriptions (continued)
Field
Description
0
1
1–7
F1WM
FIFO 1 blocking mode
FIFO 1 overwrite mode
Rx FIFO 1 Watermark
NOTE: This field has Protected Write status.
0
1-64
>64
8
Reserved
Watermark interrupt disabled
Level for Rx FIFO 1 watermark interrupt (IR[RF1W])
Watermark interrupt disabled
This field is reserved.
This read-only field is reserved and always has the value 0.
9–15
F1S
Rx FIFO 1 Size
The Rx FIFO 1 elements are indexed from 0 to F1S - 1.
NOTE: This field has Protected Write status.
0
1-64
>64
16–29
F1SA
No Rx FIFO 1
Number of Rx FIFO 1 elements
Values greater than 64 are interpreted as 64
Rx FIFO 1 Start Address
Start address of Rx FIFO 1 in Message RAM (32-bit word address, see Message RAM).
NOTE: This field has Protected Write status.
30–31
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
3.3.30 Rx FIFO 1 Status Register (M_CAN_RXF1S)
Address: 0h base + B4h offset = B4h
Bit
0
1
2
3
DMS
R
4
5
0
6
7
RF1L
F1F
8
9
10
11
12
0
13
14
15
F1PI
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
R
Reserved
F1GI
0
F1FL
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_RXF1S field descriptions
Field
0–1
DMS
Description
Debug Message Status
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Memory Map and Register Description
M_CAN_RXF1S field descriptions (continued)
Field
Description
00
01
10
11
2–5
Reserved
Idle state, wait for reception of debug messages, DMA request is cleared
Debug message A received
Debug messages A, B received
Debug messages A, B, C received, DMA request is set
This field is reserved.
This read-only field is reserved and always has the value 0.
6
RF1L
Rx FIFO 1 Message Lost
This bit is a copy of interrupt flag IR[RF1L]. When IR[RF1L] is reset, this bit is also reset.
NOTE: Overwriting the oldest message when RXF1C[F1OM] = 1 will not set this flag.
0
1
7
F1F
No Rx FIFO 1 message lost
Rx FIFO 1 message lost, also set after write attempt to Rx FIFO 1 of size zero
Rx FIFO 1 Full
0
1
8–9
Reserved
Rx FIFO 1 not full
Rx FIFO 1 full
This field is reserved.
This read-only field is reserved and always has the value 0.
10–15
F1PI
Rx FIFO 1 Put Index
16–17
Reserved
This field is reserved.
18–23
F1GI
Rx FIFO 1 Get Index
Rx FIFO 1 write index pointer, range 0 to 63.
Rx FIFO 1 read index pointer, range 0 to 63.
24
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
25–31
F1FL
Rx FIFO 1 Fill Level
Number of elements stored in Rx FIFO 1, range 0 to 64.
3.3.31 Rx FIFO 1 Acknowledge Register (M_CAN_RXF1A)
Address: 0h base + B8h offset = B8h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
0
R
0
0
0
0
0
0
0
0
0
0
0
0
0
29
30
31
0
0
F1AI
W
Reset
28
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_RXF1A field descriptions
Field
0–25
Reserved
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
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M_CAN_RXF1A field descriptions (continued)
Field
Description
26–31
F1AI
Rx FIFO 1 Acknowledge Index
After the CPU has read a message or a sequence of messages from Rx FIFO 1 it has to write the buffer
index of the last element read from Rx FIFO 1 to F1AI. This will set the Rx FIFO 1 Get Index RXF1S[F1GI]
to F1AI + 1 and update the FIFO 1 Fill Level RXF1S[F1FL].
3.3.32 Rx Buffer / FIFO Element Size Configuration Register
(M_CAN_RXESC)
Configures the number of data bytes belonging to an Rx Buffer / Rx FIFO element. Data
field sizes >8 bytes are intended for CAN FD operation only.
NOTE
In case the data field size of an accepted CAN frame exceeds
the data field size configured for the matching Rx Buffer or Rx
FIFO, only the number of bytes as configured by RXESC are
stored to the Rx Buffer resp. Rx FIFO element. The rest of the
frame’s data field is ignored.
Address: 0h base + BCh offset = BCh
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
R
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
R
Reset
0
0
0
RBDS
W
0
0
0
0
0
0
0
0
F1DS
0
0
0
0
F0DS
0
0
0
M_CAN_RXESC field descriptions
Field
0–20
Reserved
21–23
RBDS
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Rx Buffer Data Field Size
NOTE: This field has Protected Write status.
000
001
010
011
100
8 byte data field
12 byte data field
16 byte data field
20 byte data field
24 byte data field
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Memory Map and Register Description
M_CAN_RXESC field descriptions (continued)
Field
Description
101
110
111
24
Reserved
25–27
F1DS
32 byte data field
48 byte data field
64 byte data field
This field is reserved.
This read-only field is reserved and always has the value 0.
Rx FIFO 1 Data Field Size
NOTE: This field has Protected Write status.
000
001
010
011
100
101
110
111
28
Reserved
29–31
F0DS
8 byte data field
12 byte data field
16 byte data field
20 byte data field
24 byte data field
32 byte data field
48 byte data field
64 byte data field
This field is reserved.
This read-only field is reserved and always has the value 0.
Rx FIFO 0 Data Field Size
NOTE: This field has Protected Write status.
000
001
010
011
100
101
110
111
8 byte data field
12 byte data field
16 byte data field
20 byte data field
24 byte data field
32 byte data field
48 byte data field
64 byte data field
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Chapter 3 Modular CAN (M_CAN)
3.3.33 Tx Buffer Configuration Register (M_CAN_TXBC)
NOTE
Be aware that the sum of TFQS and NDTB may be not greater
than 32. There is no check for erroneous configurations. The Tx
Buffers section in the Message RAM starts with the dedicated
Tx Buffers.
Address: 0h base + C0h offset = C0h
0
R
0
W
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0
TFQM
Bit
TFQS
NDTB
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
R
TBSA
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_TXBC field descriptions
Field
0
Reserved
1
TFQM
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Tx FIFO/Queue Mode
NOTE: This field has Protected Write status.
0
1
2–7
TFQS
Tx FIFO operation
Tx Queue operation
Transmit FIFO/Queue Size
NOTE: This field has Protected Write status.
0
1-32
>32
8–9
Reserved
No Tx FIFO/Queue
Number of Tx Buffers used for Tx FIFO/Queue
Values greater than 32 are interpreted as 32
This field is reserved.
This read-only field is reserved and always has the value 0.
Table continues on the next page...
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Memory Map and Register Description
M_CAN_TXBC field descriptions (continued)
Field
Description
10–15
NDTB
Number of Dedicated Transmit Buffers
NOTE: This field has Protected Write status.
0
1-32
>32
16–29
TBSA
No Dedicated Tx Buffers
Number of Dedicated Tx Buffers
Values greater than 32 are interpreted as 32
Tx Buffers Start Address
Start address of Tx Buffers section in Message RAM (32-bit word address, see Message RAM ).
NOTE: This field has Protected Write status.
30–31
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
3.3.34 Tx FIFO/Queue Status Register (M_CAN_TXFQS)
The Tx FIFO/Queue status is related to the pending Tx requests listed in register TXBRP.
Therefore the effect of Add/Cancellation requests may be delayed due to a running Tx
scan (TXBRP not yet updated).
NOTE
In case of mixed configurations where dedicated Tx Buffers are
combined with a Tx FIFO or a Tx Queue, the Put and Get
Indices indicate the number of the Tx Buffer starting with the
first dedicated Tx Buffers.
Example: For a configuration of 12 dedicated Tx Buffers and a
Tx FIFO of 20 Buffers a Put Index of 15 points to the fourth
buffer of the Tx FIFO.
Address: 0h base + C4h offset = C4h
Bit
0
1
2
3
4
5
6
7
8
9
0
R
10
11
12
TFQF
13
14
15
TFQPI
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
0
R
TFGI
0
TFFL
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
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M_CAN_TXFQS field descriptions
Field
Description
0–9
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
10
TFQF
Tx FIFO/Queue Full
11–15
TFQPI
Tx FIFO/Queue Put Index
0
1
Tx FIFO/Queue not full
Tx FIFO/Queue full
Tx FIFO/Queue write index pointer, range 0 to 31.
16–18
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
19–23
TFGI
Tx FIFO Get Index
Tx FIFO read index pointer, range 0 to 31. Read as zero when Tx Queue operation is configured
(TXBC[TFQM] = 1).
24–25
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
26–31
TFFL
Tx FIFO Free Level
Number of consecutive free Tx FIFO elements starting from TFGI, range 0 to 32. Read as zero when Tx
Queue operation is configured (TXBC[TFQM] = 1).
3.3.35 Tx Buffer Element Size Configuration (M_CAN_TXESC)
Configures the number of data bytes belonging to a Tx Buffer element. Data field sizes >
8 bytes are intended for CAN FD operation only.
Address: 0h base + C8h offset = C8h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
0
R
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
31
TBDS
W
Reset
30
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_TXESC field descriptions
Field
0–28
Reserved
29–31
TBDS
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Tx Buffer Data Field Size
NOTE: In case the data length code DLC of a Tx Buffer element is configured to a value higher than the
Tx Buffer data field size TXESC[TBDS], the bytes not defined by the Tx Buffer are transmitted as
0xCC (padding bytes).
NOTE: This field has Protected Write status.
Table continues on the next page...
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Memory Map and Register Description
M_CAN_TXESC field descriptions (continued)
Field
Description
000
001
010
011
100
101
110
111
8 byte data field
12 byte data field
16 byte data field
20 byte data field
24 byte data field
32 byte data field
48 byte data field
64 byte data field
3.3.36 Tx Buffer Request Pending Register (M_CAN_TXBRP)
NOTE
TXBRP bits which are set while a Tx scan is in progress are not
considered during this particular Tx scan. In case a cancellation
is requested for such a Tx Buffer, this Add Request is cancelled
immediately, the corresponding TXBRP bit is reset.
Address: 0h base + CCh offset = CCh
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
TRP
R
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_TXBRP field descriptions
Field
0–31
TRP
Description
Transmission Request Pending
Each Tx Buffer has its own Transmission Request Pending bit. The bits are set via register TXBAR. The
bits are reset after a requested transmission has completed or has been cancelled via register TXBCR.
TXBRP bits are set only for those Tx Buffers configured via TXBC. After a TXBRP bit has been set, a Tx
scan (see Tx Handling) is started to check for the pending Tx request with the highest priority (Tx Buffer
with lowest Message ID).
A cancellation request resets the corresponding transmission request pending bit of register TXBRP. In
case a transmission has already been started when a cancellation is requested, this is done at the end of
the transmission, regardless whether the transmission was successful or not. The cancellation request bits
are reset directly after the corresponding TXBRP bit has been reset.
After a cancellation has been requested, a finished cancellation is signaled via TXBCF
•
•
•
•
after successful transmission together with the corresponding TXBTO bit
when the transmission has not yet been started at the point of cancellation
when the transmission has been aborted due to lost arbitration
when an error occurred during frame transmission
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M_CAN_TXBRP field descriptions (continued)
Field
Description
In DAR mode all transmissions are automatically cancelled if they are not successful. The corresponding
TXBCF bit is set for all unsuccessful transmissions.
0
1
No transmission request pending
Transmission request pending
3.3.37 Tx Buffer Add Request Register (M_CAN_TXBAR)
NOTE
If an add request is applied for a Tx Buffer with pending
transmission request (corresponding TXBRP bit already set),
this add request is ignored.
Address: 0h base + D0h offset = D0h
Bit
R
W
0
Reset
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
AR
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_TXBAR field descriptions
Field
Description
0–31
AR
Add Request
Each Tx Buffer has its own Add Request bit. Writing 1 will set the corresponding Add Request bit; writing 0
has no impact. This enables the CPU to set transmission requests for multiple Tx Buffers with one write to
TXBAR. TXBAR bits are set only for those Tx Buffers configured via TXBC. When no Tx scan is running,
the bits are reset immediately, else the bits remain set until the Tx scan process has completed.
0
1
No transmission request added
Transmission requested added
3.3.38 Tx Buffer Cancellation Request Register (M_CAN_TXBCR)
Address: 0h base + D4h offset = D4h
Bit
R
W
0
Reset
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
CR
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
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Memory Map and Register Description
M_CAN_TXBCR field descriptions
Field
Description
0–31
CR
Cancellation Request
Each Tx Buffer has its own Cancellation Request bit. Writing 1 will set the corresponding Cancellation
Request bit; writing 0 has no impact. This enables the CPU to set cancellation requests for multiple Tx
Buffers with one write to TXBCR. TXBCR bits are set only for those Tx Buffers configured via TXBC. The
bits remain set until the corresponding bit of TXBRP is reset.
0
1
No cancellation pending
Cancellation pending
3.3.39 Tx Buffer Transmission Occurred Register (M_CAN_TXBTO)
Address: 0h base + D8h offset = D8h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
TO
R
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_TXBTO field descriptions
Field
Description
0–31
TO
Transmission Occurred
Each Tx Buffer has its own Transmission Occurred bit. The bits are set when the corresponding TXBRP
bit is cleared after a successful transmission. The bits are reset when a new transmission is requested by
writing 1 to the corresponding bit of register TXBAR.
0
1
No transmission occurred
Transmission occurred
3.3.40 Tx Buffer Cancellation Finished Register (M_CAN_TXBCF)
Address: 0h base + DCh offset = DCh
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
CF
R
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_TXBCF field descriptions
Field
0–31
CF
Description
Cancellation Finished
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M_CAN_TXBCF field descriptions (continued)
Field
Description
Each Tx Buffer has its own Cancellation Finished bit. The bits are set when the corresponding TXBRP bit
is cleared after a cancellation was requested via TXBCR. In case the corresponding TXBRP bit was not
set at the point of cancellation, CF is set immediately. The bits are reset when a new transmission is
requested by writing 1 to the corresponding bit of register TXBAR.
0
1
No transmit buffer cancellation
Transmit buffer cancellation finished
3.3.41 Tx Buffer Transmission Interrupt Enable Register
(M_CAN_TXBTIE)
Address: 0h base + E0h offset = E0h
Bit
R
W
0
Reset
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
TIE
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_TXBTIE field descriptions
Field
Description
0–31
TIE
Transmission Interrupt Enable
Each Tx Buffer has its own Transmission Interrupt Enable bit.
0
1
Transmission interrupt disabled
Transmission interrupt enable
3.3.42 Tx Buffer Cancellation Finished Interrupt Enable Register
(M_CAN_TXBCIE)
Address: 0h base + E4h offset = E4h
Bit
R
W
0
Reset
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
CFIE
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_TXBCIE field descriptions
Field
0–31
CFIE
Description
Cancellation Finished Interrupt Enable
Each Tx Buffer has its own Cancellation Finished Interrupt Enable bit.
0
1
Cancellation finished interrupt disabled
Cancellation finished interrupt enabled
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Memory Map and Register Description
3.3.43 Tx Event FIFO Configuration Register (M_CAN_TXEFC)
Address: 0h base + F0h offset = F0h
Bit
0
1
2
3
0
R
0
5
6
7
8
0
0
0
0
0
9
10
11
0
EFWM
W
Reset
4
0
0
0
12
13
14
15
16
17
18
19
20
21
EFS
0
0
0
0
0
22
23
24
25
26
27
28
29
30
EFSA
0
0
0
0
0
0
0
0
0
0
31
0
0
0
0
0
0
0
0
0
M_CAN_TXEFC field descriptions
Field
0–1
Reserved
2–7
EFWM
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Event FIFO Watermark
NOTE: This field has Protected Write status.
0
1-32
>32
8–9
Reserved
10–15
EFS
Watermark interrupt disabled
Level for Tx Event FIFO watermark interrupt (IR[TEFW])
Watermark interrupt disabled
This field is reserved.
This read-only field is reserved and always has the value 0.
Event FIFO Size
The Tx Event FIFO elements are indexed from 0 to EFS - 1
NOTE: This field has Protected Write status.
0
1-32
>32
16–29
EFSA
Tx Event FIFO disabled
Number of Tx Event FIFO elements
Values greater than 32 are interpreted as 32
Event FIFO Start Address
Start address of Tx Event FIFO in Message RAM (32-bit word address, Message RAM).
NOTE: This field has Protected Write status.
30–31
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
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3.3.44 Tx Event FIFO Status Register (M_CAN_TXEFS)
Address: 0h base + F4h offset = F4h
Bit
0
1
2
3
4
5
0
R
6
7
TEFL
EFF
8
9
10
11
12
0
13
14
15
EFPI
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0
0
0
R
EFGI
0
EFFL
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_TXEFS field descriptions
Field
0–5
Reserved
6
TEFL
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Tx Event FIFO Element Lost
This bit is a copy of interrupt flag IR[TEFL]. When IR[TEFL] is reset, this bit is also reset.
0
1
7
EFF
8–10
Reserved
11–15
EFPI
16–18
Reserved
19–23
EFGI
24–25
Reserved
26–31
EFFL
No Tx Event FIFO element lost
Tx Event FIFO element lost, also set after write attempt to Tx Event FIFO of size zero
Event FIFO Full
0
1
Tx Event FIFO not full
Tx Event FIFO full
This field is reserved.
This read-only field is reserved and always has the value 0.
Event FIFO Put Index
Tx Event FIFO write index pointer, range 0 to 31.
This field is reserved.
This read-only field is reserved and always has the value 0.
Event FIFO Get Index
Tx Event FIFO read index pointer, range 0 to 31.
This field is reserved.
This read-only field is reserved and always has the value 0.
Event FIFO Fill Level
Number of elements stored in Tx Event FIFO, range 0 to 32.
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Message RAM
3.3.45 Tx Event FIFO Acknowledge Register (M_CAN_TXEFA)
Address: 0h base + F8h offset = F8h
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
0
R
0
0
0
0
0
0
0
0
0
0
0
0
0
0
30
31
0
0
EFAI
W
Reset
29
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M_CAN_TXEFA field descriptions
Field
0–26
Reserved
27–31
EFAI
Description
This field is reserved.
This read-only field is reserved and always has the value 0.
Event FIFO Acknowledge Index
After the CPU has read an element or a sequence of elements from the Tx Event FIFO it has to write the
index of the last element read from Tx Event FIFO to EFAI. This will set the Tx Event FIFO Get Index
TXEFS[EFGI] to EFAI + 1 and update the Event FIFO Fill Level TXEFS[EFFL].
3.4 Message RAM
For storage of Rx/Tx messages and for storage of the filter configuration a single- or
dual-ported Message RAM must be connected to the M_CAN module.
The Message RAM has a width of 32 bits. In case parity checking or ECC is used, a
corresponding number of bits must be added to each word.
When operated in CAN FD mode, the required Message RAM size strongly depends on
the element size configured for Rx FIFO0, Rx FIFO1, Rx Buffers, and Tx Buffers via
RXESC[F0DS], RXESC[F1DS], RXESC[RBDS], and TXESC[TBDS], respectively.
The M_CAN module can be configured to allocate up to 4352 words in the Message
RAM. For the actual amount of Message RAM on this chip, see the chip-specific
M_CAN information.
It is not necessary to configure each of the sections listed in the following figure, and
there is no restriction with respect to the sequence of the sections.
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Start Address
SIDFC[FLSSA]
XIDFC[FLESA]
11-bit Filter
0-128 elements / 0-128 words
29-bit Filter
0-64 elements / 0-128 words
RXF0C[F0SA]
Rx FIFO 0
0-64 elements / 0-1152 words
max. 4352 words
RXF1C[F1SA]
RXBC[RBSA]
TXEFC[EFSA]
TXBC[TBSA]
Rx FIFO 1
0-64 elements / 0-1152 words
Rx Buffers
0-64 elements / 0-1152 words
Tx Event FIFO
0-32 elements / 0-64 words
Tx Buffers
0-32 elements / 0-576 words
32 bits
Figure 3-48. Message RAM configuration
When the M_CAN addresses the Message RAM, it addresses 32-bit words, not single
bytes. The configurable start addresses are 32-bit word addresses: only bits 15 to 2 are
evaluated, and the two least significant bits are ignored.
NOTE
The M_CAN does not check for erroneous configuration of the
Message RAM. To avoid falsification or loss of data, carefully
configure in particular the start addresses of the different
sections and the number of elements of each section.
3.4.1 Rx Buffer and FIFO Element
Up to 64 Rx Buffers and two Rx FIFOs can be configured in the Message RAM. Each Rx
FIFO section can be configured to store up to 64 received messages. The structure of a
Rx Buffer / FIFO element is shown in the following table. The element size can be
configured for storage of CAN FD messages with up to 64 bytes data field via register
RXESC.
Table 3-48. Rx Buffer and FIFO Element
31
R0
24 23
16 15
8 7
0
X R
E
T T ID[28:0]
SI
D R
Table continues on the next page...
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Message RAM
R1
ANMF
Table 3-48. Rx Buffer and FIFO Element (continued)
FIDX[6:0]
res
E B
D R DLC[3:0]
L S
RXTS[15:0]
R2
DB3[7:0]
DB2[7:0]
DB1[7:0]
DB0[7:0]
R3
DB7[7:0]
DB6[7:0]
DB5[7:0]
DB4[7:0]
...
...
...
...
DBm[7:0]
DBm-1[7:0]
DBm-2[7:0]
DBm-3[7:0]
Rn
Table 3-49. Rx Buffer and FIFO Element Descriptions
R0 Bit 31
ESI: Error State Indicator
0 Transmitting node is error active
1 Transmitting node is error passive
R0 Bit 30
XTD: Extended Identifier
Signals to the Host whether the received frame has a standard or extended identifier.
0 11-bit standard identifier
1 29-bit standard identifier
R0 Bit 29
RTR: Remote Transmission Request
Signals to the Host whether the received frame is a data frame or a remote frame.
0 Received frame is a data frame
1 Received frame is a remote frame
NOTE: There are no remote frames in CAN FD format. In case a CAN FD frame was received
(EDL = 1), bit RTR reflects the state of the reserved bit r1.
R0 Bits 28:0
ID[28:0]: Identifier
Standard or extended identifier depending on bit XTD. A standard identifier is stored into ID[28:18].
R1 Bit 31
ANMF: Accepted Non-matching Frame
Acceptance of non-matching frames may be enabled via GFC[ANFS] and GFC[ANFE].
0 Received frame matching filter index FIDX
1 Received frame did not match any Rx filter element
R1 Bits 30:24
FIDX[6:0]: Filter Index
0-127 Index of matching Rx acceptance filter element (invalid if ANMF = 1). Range is 0 to
SIDFC[LSS] - 1 resp. XIDFC[LSE] - 1.
R1 Bit 21
EDL: Extended Data Length
0 Standard frame format
1 CAN FD frame format (new DLC-coding and CRC)
R1 Bit 20
BRS: Bit Rate Switch
0 Frame received without bit rate switching
1 Frame received with bit rate switching
Table continues on the next page...
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Table 3-49. Rx Buffer and FIFO Element Descriptions (continued)
R1 Bits 19:16
DLC[3:0]: Data Length Code
0-8 CAN + CAN FD: received frame has 0-8 data bytes
9-15 CAN: received frame has 8 data bytes
9-15 CAN FD: received frame has 12/16/20/24/32/48/64 data bytes
R1 Bits 15:0
RXTS[15:0]: Rx Timestamp
Timestamp Counter value captured on start of frame reception. Resolution depending on
configuration of the Timestamp Counter Prescaler TSCC[TCP].
R2 Bits 31:24
DB3[7:0]: Data Byte 3
R2 Bits 23:16
DB2[7:0]: Data Byte 2
R2 Bits 15:8
DB1[7:0]: Data Byte 1
R2 Bits 7:0
DB0[7:0]: Data Byte 0
R3 Bits 31:24
DB7[7:0]: Data Byte 7
R3 Bits 23:16
DB6[7:0]: Data Byte 6
R3 Bits 15:8
DB5[7:0]: Data Byte 5
R3 Bits 7:0
DB4[7:0]: Data Byte 4
...
...
Rn Bits 31:24
DBm[7:0]: Data Byte m
Rn Bits 23:16
DBm-1[7:0]: Data Byte m-1
Rn Bits 15:8
DBm-2[7:0]: Data Byte m-2
Rn Bits 7:0
DBm-3[7:0]: Data Byte m-3
NOTE
Depending on the configuration of the element size (RXESC),
between two and sixteen 32-bit words (Rn = 3 ..17) are used for
storage of a CAN message’s data field.
3.4.2 Tx Buffer Element
The Tx Buffers section can be configured to hold dedicated Tx Buffers as well as a Tx
FIFO / Tx Queue. In case that the Tx Buffers section is shared by dedicated Tx buffers
and a Tx FIFO / Tx Queue, the dedicated Tx Buffers start at the beginning of the Tx
Buffers section followed by the buffers assigned to the Tx FIFO or Tx Queue. The Tx
Handler distinguishes between dedicated Tx Buffers and Tx FIFO / Tx Queue by
evaluating the Tx Buffer configuration TXBC.TFQS and TXBC.NDTB. The element size
can be configured for storage of CAN FD messages with up to 64 bytes data field via
register TXESC.
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Table 3-50. Tx Buffer Element
31
24 23
16 15
8 7
T0
X R
re
T T ID[28:0]
s
D R
T1
MM[7:0]
T2
DB3[7:0]
DB2[7:0]
DB1[7:0]
DB0[7:0]
T3
DB7[7:0]
DB6[7:0]
DB5[7:0]
DB4[7:0]
...
...
...
...
...
Tn
DBm[7:0]
DBm-1[7:0]
DBm-2[7:0]
DBm-3[7:0]
DLC[3:0]
EF
C
res
0
res
Table 3-51. Tx Buffer Element Description
T0 Bit 30
XTD: Extended Identifier
0 11-bit standard identifier
1 29-bit extended identifier
T0 Bit 29
RTR: Remote Transmission Request
0 Transmit data frame
1 Transmit remote frame
NOTE: When RTR = 1, the M_CAN transmits a remote frame according to ISO11898-1, even if
CCCR[CME] enables the transmission in CAN FD format.
T0 Bit 28:0
ID[28:0]: Identifier
Standard or extended identifier depending on bit XTD. A standard identifier has to be written to
ID[28:18].
T1 Bits 31:24
MM[7:0]: Message Marker
Written by CPU during Tx Buffer configuration. Copied into Tx Event FIFO element for identification of
Tx message status.
T1 Bit 23
EFC: Event FIFO Control
0 Do not store Tx events
1 Store Tx events
T1 Bits 19:16
DLC[3:0]: Data Length Code
0-8 CAN + CAN FD: Transmit frame has 0-8 data bytes
9-15 CAN: Transmit frame has 8 data bytes
9-15 CAN FD: Transmit frame has 12/16/20/24/32/48/64 data bytes
T2 Bits 31:24
DB3[7:0]: Data Byte 3
T2 Bits 23:16
DB2[7:0]: Data Byte 2
T2 Bits 15:8
DB1[7:0]: Data Byte 1
T2 Bits 7:0
DB0[7:0]: Data Byte 0
T3 Bits 31:24
DB7[7:0]: Data Byte 7
T3 Bits 23:16
DB6[7:0]: Data Byte 6
T3 Bits 15:8
DB5[7:0]: Data Byte 5
T3 Bits 7:0
DB4[7:0]: Data Byte 4
Table continues on the next page...
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Table 3-51. Tx Buffer Element Description (continued)
...
...
Tn Bits 31:24
DBm[7:0]: Data Byte m
Tn Bits 23:16
DBm-1[7:0]: Data Byte m-1
Tn Bits 15:8
DBm-2[7:0]: Data Byte m-2
Tn Bits 7:0
DBm-3[7:0]: Data Byte m-3
NOTE
Depending on the configuration of the element size (TXESC),
between two and sixteen 32-bit words (Tn = 3 ..17) are used for
storage of a CAN message’s data field.
3.4.3 Tx Event FIFO Element
Each element stores information about transmitted messages. By reading the Tx Event
FIFO the Host CPU gets this information in the order the messages were transmitted.
Status information about the Tx Event FIFO can be obtained from register TXEFS.
Table 3-52. Tx Event FIFO Element
31
E0
24 23
16 15
8 7
0
X R
E
T T ID[28:0]
SI
D R
E1
E B
ET[1:
D R DLC[3:0]
0]
L S
MM[7:0]
TXTS[15:0]
Table 3-53. Tx Event FIFO Element Description
E0 Bit 31
ESI: Error State Indicator
0 Transmitting node is error active
1 Transmitting node is error passive
E0 Bit 30
XTD: Extended Identifier
0 11-bit standard identifier
1 29-bit extended identifier
E0 Bit 29
RTR: Remote Transmission Request
0 Data frame transmitted
1 Remote frame transmitted
E0 Bits 28:0
ID[28:0]: Identifier
Standard or extended identifier depending on bit XTD. A standard identifier is stored into ID[28:18].
Table continues on the next page...
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Message RAM
Table 3-53. Tx Event FIFO Element Description (continued)
E1 Bits 31:24
MM[7:0]: Message Marker
Copied from Tx Buffer into Tx Event FIFO element for identification of Tx message status.
E1 Bit 23:22
ET[1:0]: Event Type
00 Reserved
01 Tx event
10 Transmission in spite of cancellation (always set for transmissions in DAR mode)
11 Reserved
E1 Bit 21
EDL: Extended Data Length
0 Standard frame format
1 CAN FD frame format (new DLC-coding and CRC)
E1 Bit 20
BRS: Bit Rate Switch
0 Frame transmitted without bit rate switching
1 Frame transmitted with bit rate switching
E1 Bits 19:16
DLC[3:0]: Data Length Code
0-8 CAN + CAN FD: Frame with 0-8 data bytes transmitted
9-15 CAN: Frame with 8 data bytes transmitted
9-15 CAN FD: frame with 12/16/20/24/32/48/64 data bytes transmitted
E1 Bits 15:0
TXTS[15:0]: Tx Timestamp
Timestamp Counter value captured on start of frame transmission. Resolution depending on
configuration of the Timestamp Counter Prescaler TSCC.TCP.
3.4.4 Standard Message ID Filter Element
Up to 128 filter elements can be configured for 11-bit standard IDs. When accessing a
Standard Message ID Filter element, its address is the Filter List Standard Start Address
SIDFC[FLSSA] plus the index of the filter element (0…127).
Table 3-54. Standard Message ID Filter Element
S0
SFT[1:0]
31
24 23
SFEC[2:0
SFID1[10:0]
]
16 15
8 7
res
SFID2[10:0]
0
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Table 3-55. Standard Message ID Filter Element Field Description
S0 Bits 31:30
SFT[1:0]: Standard Filter Type
00 Range filter from SFID1 to SFID2 (SFID2 >= SFID1)
01 Dual ID filter for SFID1 or SFID2
10 Classic filter: SFID1 = filter, SFID2 = mask
11 Reserved
S0 Bits 29:27
SFEC[2:0]: Standard Filter Element Configuration
All enabled filter elements are used for acceptance filtering of standard frames. Acceptance filtering
stops at the first matching enabled filter element or when the end of the filter list is reached. If SFEC
= 100, 101, or 110 a match sets interrupt flag IR[HPM] and, if enabled, an interrupt is generated.
In this case register HPMS is updated with the status of the priority match.
000 Disable filter element
001 Store in Rx FIFO 0 if filter matches
010 Store in Rx FIFO 1 if filter matches
011 Reject ID if filter matches
100 Set priority if filter matches
101 Set priority and store in FIFO 0 if filter matches
110 Set priority and store in FIFO 1 if filter matches
111 Store into Rx Buffer or as debug message, configuration of SFT[1:0] ignored
S0 Bits 26:16
SFID1[10:0]: Standard Filter ID 1
First ID of standard ID filter element.
When filtering for Rx Buffers or for debug messages this field defines the ID of a standard message
to be stored. The received identifiers must match exactly, no masking mechanism is used.
S0 Bits 10:0
SFID2[10:0]: Standard Filter ID 2
Overall, this bit field has a different meaning depending on the configuration of SFEC:
SFEC = 001...110 Second ID of standard ID filter element
SFEC = 111 Filter for Rx Buffers or for debug messages
SFID2[10:9]: Decides whether the received message is stored into an Rx Buffer or treated as
message A, B, or C of the debug message sequence.
00 Store message into an Rx Buffer
01 Debug Message A
10 Debug Message B
11 Debug Message C
SFID2[8:6]: Is used to control the M_CAN filter event pins at the Extension Interface. A one at the
respective bit position enables generation of a pulse at the related filter event pin with the duration
of one Host clock period in case the filter matches.
SFID2[5:0]: Defines the offset to the Rx Buffer Start Address RXBC.RBSA for storage of a matching
message.
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3.4.5 Extended Message ID Filter Element
Up to 64 filter elements can be configured for 29-bit extended IDs. When accessing an
Extended Message ID Filter element, its address is the Filter List Extended Start Address
XIDFC[FLESA] plus two times the index of the filter element (0…63).
Table 3-56. Extended Message ID Filter Element
31
res
F1
16 15
8 7
0
EFEC[2:0
EFID1[28:0]
]
EFT[1:0]
F0
24 23
EFID2[28:0]
Table 3-57. Extended Message ID Filter Element Field Description
F0 Bits 31:29
EFEC[2:0]: Extended Filter Element Configuration
All enabled filter elements are used for acceptance filtering of extended frames. Acceptance filtering
stops at the first matching enabled filter element or when the end of the filter list is reached. If EFEC
= 100, 101, or 110 a match sets interrupt flag IR[HPM] and, if enabled, an interrupt is generated. In
this case register HPMS is updated with the status of the priority match.
000 Disable filter element
001 Store in Rx FIFO 0 if filter matches
010 Store in Rx FIFO 1 if filter matches
011 Reject ID if filter matches
100 Set priority if filter matches
101 Set priority and store in FIFO 0 if filter matches
110 Set priority and store in FIFO 1 if filter matches
111 Store into Rx Buffer or as debug message, configuration of EFT[1:0] ignored
F0 Bits 28:0
EFID1[28:0]: Extended Filter ID 1
First ID of extended ID filter element.
When filtering for Rx Buffers or for debug messages this field defines the ID of an extended
message to be stored. The received identifiers must match exactly, only XIDAM masking
mechanism is used.
F1 Bits 31:30
EFT[1:0]: Extended Filter Type
00 Range filter from EFID1 to EFID2 (EFID2 >= EFID1)
01 Dual ID filter for EFID1 or EFID2
10 Classic filter: EFID1 = filter, EFID2 = mask
11 Range filter from EFID1 to EFID2 (EFID2 >= EFID1), XIDAM mask not applied
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Table 3-57. Extended Message ID Filter Element Field Description (continued)
F1 Bits 28:0
EFID2[28:0]: Extended Filter ID 2
Overall, this bit field has a different meaning depending on the configuration of EFEC:
EFEC = 001...110 Second ID of extended ID filter element
EFEC = 111 Filter for Rx Buffers or for debug messages
EFID2[10:9]: Decides whether the received message is stored into an Rx Buffer or treated as
message A, B, or C of the debug message sequence.
00 Store message into an Rx Buffer
01 Debug Message A
10 Debug Message B
11 Debug Message C
EFID2[8:6]: Is used to control the filter event pins at the Extension Interface. A one at the respective
bit position enables generation of a pulse at the related filter event pin with the duration of one Host
clock period in case the filter matches.
EFID2[5:0]: Defines the offset to the Rx Buffer Start Address RXBC[RBSA] for storage of a
matching message.
3.5 Functional Description
3.5.1 Operating Modes
3.5.1.1 Software Initialization
Software initialization is started by setting bit CCCR[INIT], either by software or by a
hardware reset, when an uncorrected bit error was detected in the Message RAM, or by
going Bus_Off. While CCCR[INIT] is set, message transfer from and to the CAN bus is
stopped, the status of the CAN bus output M_CAN_Tx is recessive (HIGH). The
counters of the Error Management Logic EML are unchanged. Setting CCCR[INIT] does
not change any configuration register. Resetting CCCR[INIT] finishes the software
initialization. Afterwards the Bit Stream Processor BSP synchronizes itself to the data
transfer on the CAN bus by waiting for the occurrence of a sequence of 11 consecutive
recessive bits (= Bus_Idle) before it can take part in bus activities and start the message
transfer.
Access to the M_CAN configuration registers is only enabled when both bits
CCCR[INIT] and CCCR[CCE] are set (protected write).
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Functional Description
CCCR[CCE] can only be set/reset while CCCR[INIT] = 1. CCCR[CCE] is automatically
reset when CCCR[INIT] is reset.
The following registers are reset when CCCR[CCE] is set
• HPMS – High Priority Message Status
• RXF0S – Rx FIFO 0 Status
• RXF1S – Rx FIFO 1 Status
• TXFQS – Tx FIFO/Queue Status
• TXBRP – Tx Buffer Request Pending
• TXBTO – Tx Buffer Transmission Occurred
• TXBCF – Tx Buffer Cancellation Finished
• TXEFS – Tx Event FIFO Status
The Timeout Counter value TOCV[TOC] is preset to the value configured by
TOCC[TOP] when CCCR[CCE] is set.
In addition the state machines of the Tx Handler and Rx Handler are held in idle state
while CCCR[CCE] = 1.
The following registers are only writable while CCCR[CCE] = 0
• TXBAR – Tx Buffer Add Request
• TXBCR – Tx Buffer Cancellation Request
CCCR[TEST] and CCCR[MON] can only be set by the Host while CCCR[INIT] = 1 and
CCCR[CCE] = 1. Both bits may be reset at any time. CCCR[DAR] can only be set/reset
while CCCR[INIT] = 1 and CCCR[CCE] = 1.
3.5.1.2 Normal Operation
Once the M_CAN is initialized and CCCR.INIT is reset to zero, the M_CAN
synchronizes itself to the CAN bus and is ready for communication.
After passing the acceptance filtering, received messages including Message ID and DLC
are stored into a dedicated Rx Buffer or into Rx FIFO 0 or Rx FIFO 1.
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For messages to be transmitted dedicated Tx Buffers and/or a Tx FIFO or a Tx Queue can
be initialized or updated. Automated transmission on reception of remote frames is not
implemented.
3.5.1.3 CAN FD Operation
There are two variants in the CAN FD frame transmission, first the CAN FD frame
without bit rate switching. The second variant is the CAN FD frame where control field,
data field, and CRC field are transmitted with a higher bit rate than the beginning and the
end of the frame.
The CAN operation mode is enabled by programming CCCR[CME]. In case
CCCR[CME] = 01 transmission of long CAN FD frames and reception of long and fast
CAN FD frames is enabled. With CCCR[CME] = 10/11 transmission and reception of
long and fast CAN FD frames is enabled. CCCR[CME] can only be changed while
CCCR[INIT] and CCCR[CCE] are both set.
When initialization is left (CCCR[INIT] set to 0), the CAN FD protocol option is
inactive, it has to be requested by writing to CCCR[CMR].
A mode change requested by writing to CCCR[CMR] will be executed next time the
CAN protocol controller FSM reaches idle phase between CAN frames. Upon this event
CCCR[CMR] is reset to 00 and the status flags CCCR[FDBS] and CCCR[FDO] are set
accordingly. In case the requested CAN operation mode is not enabled, the value written
to CCCR[CMR] is retained until it is overwritten by the next mode change request.
Default is CAN operation according to ISO11898-1.
It is not necessary to change the CAN operation mode after system startup. A mode
change during CAN operation is only recommended under the following conditions:
• The failure rate in the CAN FD data phase is significant higher than in the CAN FD
arbitration phase. In this case disable the CAN FD bit rate switching option for
transmissions.
• During system startup all nodes are transmitting according to ISO11898-1 until it is
verified that they are able to communicate in CAN FD format. If this is true, all
nodes switch to CAN FD operation.
• End-of-line programming in case not all nodes are CAN FD capable. Non CAN FD
nodes are held in silent mode until programming has completed. Then all nodes
switch back to CAN communication according ISO11898-1.
When CCCR[CME] is not 00, received CAN FD frames are interpreted according to the
CAN FD Protocol Specification. The reserved bit in CAN frames with 11-bit identifiers
and the first reserved bit in CAN frames with 29-bit identifiers will be decoded as EDL
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Functional Description
bit. EDL = recessive signifies a CAN FD frame, EDL = dominant signifies a standard
CAN frame. In a CAN FD frame, the two bits following EDL, r0 and BRS, decide
whether the bit rate inside of this CAN FD frame is switched. A CAN FD bit rate switch
is signified by r0 = dominant and BRS = recessive. The coding of r0 = recessive is
reserved for future expansion of the protocol.
Reception of CAN frames according to ISO 11898-1 is possible in all CAN operation
modes.
The status bits CCCR[FDO] and CCCR[FDBS] indicate the format of transmitted frames.
When CCCR[FDO] is set, frames will be transmitted in CAN FD format with EDL =
recessive. When both CCCR[FDO] and CCCR[FDBS] are set, frames will be transmitted
in CAN FD format with bit rate switching and both bits EDL and BRS = recessive.
In the CAN FD format, the coding of the DLC differs from the standard CAN format.
The DLC codes 0 to 8 have the same coding as in standard CAN, the codes 9 to 15,
which in standard CAN all code a data field of 8 bytes, are coded according to the
following table.
Table 3-58. Coding of DLC in CAN FD
DLC
9
10
11
12
13
14
15
Number of
data bytes
12
16
20
24
32
48
64
In CAN FD frames, the bit timing will be switched inside the frame, after the BRS (Bit
Rate Switch) bit, if this bit is recessive. Before the BRS bit, in the CAN FD arbitration
phase, the standard CAN bit timing is used as defined by the Bit Timing & Prescaler
Register BTP. In the following CAN FD data phase, the fast CAN bit timing is used as
defined by the Fast Bit Timing & Prescaler Register FBTP. The bit timing is switched
back from the fast timing at the CRC delimiter or when an error is detected, whichever
occurs first.
The maximum configurable bit rate in the CAN FD data phase depends on the CAN
clock frequency. Example: with a CAN clock frequency of 20MHz and the shortest
configurable bit time of 4 tq, the bit rate in the data phase is 5 Mbit/s.
In both data frame formats, CAN FD long and CAN FD fast, the value of the bit ESI
(Error Status Indicator) is determined by the transmitter’s error state at the start of the
transmission. If the transmitter is error passive, ESI is transmitted recessive, else it is
transmitted dominant.
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3.5.1.4 Transmitter Delay Compensation
During the data phase of a CAN FD transmission only one node is transmitting, all others
are receivers. The length of the bus line has no impact. When transmitting via pin
M_CAN_Tx the M_CAN receives the transmitted data from its local CAN transceiver
via M_CAN_Rx pin. The received data is delayed by the transmitter delay. In case this
delay is greater than TSEG1 (time segment before sample point), a bit error is detected.
In order to enable a data phase bit time that is even shorter than the transmitter delay, the
delay compensation is introduced. Without transmitter delay compensation, the bit rate in
the data phase of a CAN FD frame is limited by the transmitter delay.
3.5.1.4.1
Description
The M_CAN's protocol unit has implemented a delay compensation mechanism to
compensate the transmitter delay, thereby enabling transmission with higher bit rates
during the CAN FD data phase independent of the delay of a specific CAN transceiver.
The following figure describes how the transceiver loop delay is measured.
transceiver loop delay
r0
EDL
m_can_tx
BRS
arbitration phase
E
S
I
DLC
data phase
arbitration phase
m_can_rx
Start
data phase
Stop
Delay
Measurement
transceiver delay compensation offset
(FBTP.TDCO)
secondary sample point position (TEST.TDCV)
Figure 3-49. Transceiver delay measurement
Within each CAN FD frame, the transmitter measures the delay between the data
transmitted at pin M_CAN_Tx and the data received at pin M_CAN_Rx. The
measurement is done once, at the falling edge of bit EDL to bit r0. The delay is measured
in M_CAN clock periods.
A secondary sample point position is calculated by adding a configurable transceiver
delay compensation offset FBTP[TDCO] to the measured transceiver delay. The
transceiver delay compensation value TEST[TDCV] is the sum of the measured
transceiver delay and the transceiver delay compensation offset. The transceiver delay
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Functional Description
compensation offset is chosen to adjust the secondary sample point inside the bit time
(e.g. half of the bit time in the data phase). The position of the secondary sample point is
rounded down to the next integer number of time quanta tq.
To check for bit errors during the data phase, the delayed transmit data is compared
against the received data at the secondary sample point . If a bit error is detected at the
secondary sample point, the transmitter will react to this bit error at the next following
regular sample point. During arbitration phase the delay compensation is always disabled.
For the transceiver delay compensation the following boundary conditions have to be
considered:
• The sum of the measured delay from M_CAN_Tx to M_CAN_Rx and the configured
transceiver delay compensation offset FBTP[TDCO] has to be less than 3 bit times in
the data phase.
• The sum of the measured delay from M_CAN_Tx to M_CAN_Rx and the configured
transceiver delay compensation offset FBTP[TDCO] has to be less or equal 63
M_CAN clock periods. In case this sum exceeds 63 M_CAN clock periods, the
maximum value of 63 M_CAN clock periods is used for transceiver delay
compensation.
The actual delay compensation value is monitored by reading TEST[TDCV].
3.5.1.4.2
Configuration and Status
Compensation for the transceiver loop delay by the M_CAN is enabled via FBTP.TDC.
The transceiver delay compensation offset is configured via FBTP.TDCO. The actual
delay compensation value applied by the M_CAN’s protocol engine can be read from
TEST.TDCV.
3.5.1.5 Restricted Operation Mode
In Restricted Operation Mode the node is able to receive data and remote frames and to
give acknowledge to valid frames, but it does not send data frames, remote frames, active
error frames, or overload frames. In case of an error condition or overload condition, it
does not send dominant bits, instead it waits for the occurrence of bus idle condition to
resynchronize itself to the CAN communication. The error counters are not incremented.
The Host can set the M_CAN into Restricted Operation mode by setting bit
CCCR[ASM]. The bit can only be set by the Host when both CCCR[CCE] and
CCCR[INIT] are set to 1. The bit can be reset by the Host at any time.
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Restricted Operation Mode is automatically entered when the Tx Handler was not able to
read data from the Message RAM in time. To leave Restricted Operation Mode, the Host
CPU has to reset CCCR[ASM].
The Restricted Operation Mode can be used in applications that adapt themselves to
different CAN bit rates. In this case the application tests different bit rates and leaves the
Restricted Operation Mode after it has received a valid frame.
NOTE
The Restricted Operation Mode must not be combined with the
Loop Back Mode (internal or external).
3.5.1.6 Bus Monitoring Mode
The M_CAN is set in Bus Monitoring Mode by programming CCCR.MON to one. In
Bus Monitoring Mode (see ISO11898-1, 10.12 Bus monitoring), the M_CAN is able to
receive valid data frames and valid remote frames, but cannot start a transmission. In this
mode, it sends only recessive bits on the CAN bus. If the M_CAN is required to send a
dominant bit (ACK bit, overload flag, active error flag), the bit is rerouted internally so
that the M_CAN monitors this dominant bit, although the CAN bus may remain in
recessive state. In Bus Monitoring Mode, register TXBRP is held in reset state.
The Bus Monitoring Mode can be used to analyze the traffic on a CAN bus without
affecting it by the transmission of dominant bits The following figure shows the
connection of signals M_CAN Tx and Rx to the M_CAN in Bus Monitoring Mode.
MCAN
transmit output
MCAN
receive input
=1
TX
RX
MCAN
Figure 3-50. Pin Control in Bus Monitoring Mode
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Functional Description
3.5.1.7 Disabled Automatic Retransmission
According to the CAN Specification (see ISO11898-1, 6.3.3 Recovery Management), the
M_CAN provides means for automatic retransmission of frames that have lost arbitration
or that have been disturbed by errors during transmission. By default automatic
retransmission is enabled. To support time-triggered communication as described in ISO
11898-1, chapter 9.2, the automatic retransmission may be disabled via CCCR[DAR].
3.5.1.7.1
Frame Transmission in DAR mode
In DAR mode all transmissions are automatically cancelled after they started on the CAN
bus. A Tx Buffer's Tx Request Pending bit TXBRP[TRPx] is reset after successful
transmission, when a transmission has not yet been started at the point of cancellation,
has been aborted due to lost arbitration, or when an error occurred during frame
transmission.
• Successful transmission:
• Corresponding Tx Buffer Transmission Occurred bit TXBTO[TOx] set
• Corresponding Tx Buffer Cancellation Finished bit TXBCF[CFx] not set
• Successful transmission in spite of cancellation:
• Corresponding Tx Buffer Transmission Occurred bit TXBTO[TOx] set
• Corresponding Tx Buffer Cancellation Finished bit TXBCF[CFx] set
• Arbitration lost or frame transmission disturbed:
• Corresponding Tx Buffer Transmission Occurred bit TXBTO[TOx] not set
• Corresponding Tx Buffer Cancellation Finished bit TXBCF[CFx] set
In case of a successful frame transmission, and if storage of Tx events is enabled, a Tx
Event FIFO element is written with Event Type ET = 10 (transmission in spite of
cancellation).
3.5.1.8 Power Down (Sleep Mode)
The M_CAN can be set into power down mode controlled by CC Control Register
CCCR[CSR].
When all pending transmission requests have completed, the M_CAN waits until bus idle
state is detected. Then the M_CAN sets then CCCR[INIT] to one to prevent any further
CAN transfers. Now the M_CAN acknowledges that it is ready for power down by
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setting CCCR[CSA] to one. In this state, before the clocks are switched off, further
register accesses can be made. A write access to CCCR[INIT] will have no effect. Now
the module input clocks: CAN clock and Host clock may be switched off.
To leave power down mode, the application has to turn on the module clocks before
resetting CC Control Register flag CCCR[CSR]. The M_CAN will acknowledge this by
resetting output signal clock stop acknowledge and resetting CCCR[CSA]. Afterwards,
the application can restart CAN communication by resetting bit CCCR[INIT].
3.5.1.9 Test Modes
To enable write access to register TEST, bit CCCR[TEST] has to be set to one. This
allows the configuration of the test modes and test functions.
Four output functions are available for the CAN transmit pin M_CAN_Tx by
programming TEST[TX]. Additionally to its default function – the serial data output – it
can drive the CAN Sample Point signal to monitor the M_CAN's bit timing and it can
drive constant dominant or recessive values. The actual value at pin M_CAN_Rx can be
read from TEST[RX]. Both functions can be used to check the CAN bus' physical layer.
Due to the synchronization mechanism between CAN clock and Host clock domain, there
may be a delay of several Host clock periods between writing to TEST[TX] until the new
configuration is visible at output pin M_CAN_Tx. This applies also when reading input
pin M_CAN_Rx via TEST[RX].
Note
Test modes should be used for production tests or self test only.
The software control for pin M_CAN_Tx interferes with all
CAN protocol functions. It is not recommended to use test
modes for application.
3.5.1.9.1
External Loopback Mode
The M_CAN can be set in External Loopback Mode by programming TEST[LBCK] to
one. In Loopback Mode, the M_CAN treats its own transmitted messages as received
messages and stores them (if they pass acceptance filtering) into an Rx Buffer or an Rx
FIFO. The following figure shows the connection of signals M_CAN_Tx and
M_CAN_Rx to the M_CAN in External Loopback Mode.
This mode is provided for hardware self-test. To be independent from external
stimulation, the M_CAN ignores acknowledge errors (recessive bit sampled in the
acknowledge slot of a data/remote frame) in Loopback Mode. In this mode the M_CAN
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Functional Description
performs an internal feedback from its Tx output to its Rx input. The actual value of the
input pin M_CAN_Rx is disregarded by the M_CAN. The transmitted messages can be
monitored at the pin M_CAN_Tx.
MCAN
transmit output
MCAN
receive input
RX
TX
MCAN
Figure 3-51. Pin Control in External Loopback Mode
3.5.1.9.2
Internal Loopback Mode
Internal Loopback Mode is entered by programming bits TEST[LBCK] and
CCCR[MON] to one. This mode can be used for a "Hot Selftest", meaning the M_CAN
can be tested without affecting a running CAN system connected to the pins M_CAN_Tx
and M_CAN_Rx. In this mode pin M_CAN_Rx is disconnected from the M_CAN and
pin M_CAN_Tx is held recessive. The following figure shows the connection of
M_CAN_Tx and M_CAN_Rx to the M_CAN in case of Internal Loopback Mode.
MCAN
MCAN
transmit output receive input
=1
TX
RX
MCAN
Figure 3-52. Pin Control in Internal Loopback Mode
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3.5.2 Timestamp Generation
For timestamp generation the M_CAN supplies a 16-bit wrap-around counter. A
prescaler TSCC[TCP] can be configured to clock the counter in multiples of CAN bit
times (1…16). The counter is readable via TSCV[TSC]. A write access to register TSCV
resets the counter to zero. When the timestamp counter wraps around interrupt flag
IR[TSW] is set.
On start of frame reception / transmission the counter value is captured and stored into
the timestamp section of an Rx Buffer / Rx FIFO (RXTS[15:0]) or Tx Event FIFO
(TXTS[15:0]) element.
3.5.3 Timeout Counter
To signal timeout conditions for Rx FIFO 0, Rx FIFO 1, and the Tx Event FIFO the
M_CAN supplies a 16-bit Timeout Counter. It operates as down-counter and uses the
same prescaler controlled by TSCC[TCP] as the Timestamp Counter. The Timeout
Counter is configured via register TOCC. The actual counter value can be read from
TOCV[TOC]. The Timeout Counter can only be started while CCCR[INIT] = 0. It is
stopped when CCCR[INIT] = 1, e.g. when the M_CAN enters Bus_Off state.
The operation mode is selected by TOCC[TOS]. When operating in Continuous mode,
the counter starts when CCCR[INIT] is reset. A write to TOCV presets the counter to the
value configured by TOCC[TOP] and continues down-counting.
When the Timeout Counter is controlled by one of the FIFOs, an empty FIFO presets the
counter to the value configured by TOCC[TOP]. Down-counting is started when the first
FIFO element is stored. Writing to TOCV has no effect.
When the counter reaches zero, interrupt flag IR[TOO] is set. In Continuous Mode, the
counter is immediately restarted at TOCC[TOP].
Note
The clock signal for the Timeout Counter is derived from the
CAN Core's sample point signal. Therefore the point in time
where the Timeout Counter is decremented may vary due to the
synchronization / re-synchronization mechanism of the CAN
Core. If the baud rate switch feature in CAN FD is used, the
timeout counter is clocked differently in arbitration and data
field.
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3.5.4 Rx Handling
The Rx Handler controls the acceptance filtering, the transfer of received messages to the
Rx Buffers or to one of the two Rx FIFOs, as well as the Rx FIFO's Put and Get Indices.
3.5.4.1 Acceptance filtering
The M_CAN offers the possibility to configure two sets of acceptance filters, one for
standard identifiers and one for extended identifiers. These filters can be assigned to Rx
Buffer or to Rx FIFO 0, 1. For acceptance filtering each list of filters is executed from
element #0 until the first matching element. Acceptance filtering stops at the first
matching element. The following filter elements are not evaluated for this message.
The main features are:
• Each filter element can be configured as
• Range filter (from - to)
• Filter for one or two dedicated IDs
• Classic bit mask filter
• Each filter element is configurable for acceptance or rejection filtering
• Each filter element can be enabled / disabled individually
• Filters are checked sequentially, execution stops with the first matching filter element
Related configuration registers are:
• Global Filter Configuration (GFC)
• Standard ID Filter Configuration (SIDFC)
• Extended ID Filter Configuration (XIDFC)
• Extended ID AND Mask (XIDAM)
Depending on the configuration of the filter element (SFEC/EFEC) a match triggers one
of the following actions:
• Store received frame in FIFO 0 or FIFO 1
• Store received frame in Rx Buffer
• Store received frame in Rx Buffer and generate pulse at filter event pin
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• Reject received frame
• Set High Priority Message interrupt flag IR.HPM
• Set High Priority Message interrupt flag IR.HPM and store received frame in FIFO 0
or FIFO 1
Acceptance filtering is started after the complete identifier has been received. After
acceptance filtering has completed, and if a matching Rx Buffer or Rx FIFO has been
found, the Message Handler starts writing the received message data in portions of 32 bit
to the matching Rx Buffer or Rx FIFO. If the CAN protocol controller has detected an
error condition (e.g. CRC error), this message is discarded with the following impact on
the affected Rx Buffer or Rx FIFO:
Rx Buffer
New Data flag of matching Rx Buffer is not set, but Rx Buffer (partly) overwritten with
received data. For error type see PSR[LEC] respectively PSR[FLEC].
Rx FIFO
Put index of matching Rx FIFO is not updated, but related Rx FIFO element (partly)
overwritten with received data. For error type see PSR[LEC] respectively PSR[FLEC]. In
case the matching Rx FIFO is operated in overwrite mode, the boundary conditions
described in "Rx FIFO Overwrite Mode" section have to be considered.
Note
When an accepted message is written to one of the two Rx
FIFOs, or into an Rx Buffer, the unmodified received identifier
is stored independent of the filter(s) used. The result of the
acceptance filter process is strongly depending on the sequence
of configured filter elements.
3.5.4.1.1
Range Filter
The filter matches for all received frames with Message IDs in the range defined by
SF1ID/SF2ID resp. EF1ID/EF2ID.
There are two possibilities when range filtering is used together with extended frames:
• EFT = "00": The Message ID of received frames is ANDed with the Extended ID
AND Mask (XIDAM) before the range filter is applied
• EFT = "11": The Extended ID AND Mask (XIDAM) is not used for range filtering
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Functional Description
3.5.4.1.2
Filter for Specific IDs
A filter element can be configured to filter for one or two specific Message IDs. To filter
for one specific Message ID, the filter element has to be configured with SF1ID = SF2ID
resp. EF1ID = EF2ID.
3.5.4.1.3
Classic Bit Mask Filter
Classic bit mask filtering is intended to filter groups of Message IDs by masking single
bits of a received Message ID. With classic bit mask filtering SF1ID/EF1ID is used as
Message ID filter, while SF2ID/EF2ID is used as filter mask.
A zero bit at the filter mask will mask out the corresponding bit position of the
configured ID filter, e.g. the value of the received Message ID at that bit position is not
relevant for acceptance filtering. Only those bits of the received Message ID where the
corresponding mask bits are one are relevant for acceptance filtering.
In case all mask bits are one, a match occurs only when the received Message ID and the
Message ID filter are identical. If all mask bits are zero, all Message IDs match.
3.5.4.1.4
Standard Message ID Filtering
The following figure shows the flow for standard Message ID (11-bit Identifier) filtering.
The Standard Message ID Filter element is described in Standard Message ID Filter
Element.
Controlled by the Global Filter Configuration GFC and the Standard ID Filter
Configuration SIDFC Message ID, Remote Transmission Request bit (RTR), and the
Identifier Extension bit (IDE) of received frames are compared against the list of
configured filter elements.
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valid frame received
11 bit
11 / 29 bit identifier
29 bit
yes
GFC[RRFS] = ‘1’
reject remote frames
remote frame
no
GFC[RRFS] = ‘0’
receive filter list enabled
SIDFC.LSS[7:0] = 0
SIDFC[LSS[7:0]] > 0
yes
match filter element #0
no
reject
match filter element #SIDFC[LSS]
yes
no
accept non-matching frames
acceptance / rejection
accept
GFC[ANFS[1]] = ‘1’
discard frame
GFC[ANFS[1]] = ‘0’
target FIFO full (blocking)
or Rx Buffer ND = ‘1’
yes
no
append to target FIFO
or store to Rx Buffer
Figure 3-53. Standard Message ID Filter Path
3.5.4.1.5
Extended Message ID Filtering
The figure below shows the flow for extended Message ID (29-bit Identifier) filtering.
The Extended Message ID Filter element is described in Extended Message ID Filter
Element.
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Controlled by the Global Filter Configuration GFC and the Extended ID Filter
Configuration XIDFC Message ID, Remote Transmission Request bit (RTR), and the
Identifier Extension bit (IDE) of received frames are compared against the list of
configured filter elements.
The Extended ID AND Mask XIDAM is ANDed with the received identifier before the
filter list is executed.
valid frame received
11 bit
11 / 29 bit identifier
29 bit
yes
GFC[RRFE] = ‘1’
remote frame
reject remote frames
no
GFC[RRFE] = ‘0’
receive filter list enabled
XIDFC[LSE[6:0]] > 0
match filter element #0
no
reject
acceptance / rejection
accept
match filter element # XIDFC[LSE]
yes
no
GFC[ANFE[1]] = ‘1’
discard frame
XIDFC[LSE[6:0]] = 0
yes
accept non-matching frames
GFC[ANFE[1]] = ‘0’
yes
target FIFO full(blocking)
or Rx Buffer ND =‘1’
no
append to target FIFO
or store to Rx Buffer
Figure 3-54. Extended Message ID Filter Path
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3.5.4.1.6
Rx FIFOs
Rx FIFO 0 and Rx FIFO 1 can be configured to hold up to 64 elements each.
Configuration of the two Rx FIFOs is done via registers RXF0C and RXF1C.
Received messages that passed acceptance filtering are transferred to the Rx FIFO as
configured by the matching filter element. For a description of the filter mechanisms
available for Rx FIFO 0 and Rx FIFO 1 see Acceptance filtering. The Rx FIFO element
is described in Rx Buffer and FIFO Element.
To avoid an Rx FIFO overflow, the Rx FIFO watermark can be used. When the Rx FIFO
fill level reaches the Rx FIFO watermark configured by RXFnC[FnWM], interrupt flag
IR[RFnW] is set. When the Rx FIFO Put Index reaches the Rx FIFO Get Index an Rx
FIFO Full condition is signalled by RXFnS[FnF]. In addition interrupt flag IR[RFnF] is
set.
Figure 3-55. Rx FIFO Status
When reading from an Rx FIFO, Rx FIFO Get Index RXFnS[FnGI] x FIFO Element Size
has to be added to the corresponding Rx FIFO start address RXFnC[FnSA].
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
Functional Description
Table 3-59. Rx Buffer / FIFO Element Size
RXESC.RBDS[2:0] RXESC.FnDS[2:0]
Data Field [bytes]
FIFO Element Size [RAM words]
000
8
4
001
12
5
010
16
6
011
20
7
100
24
8
101
32
10
110
48
14
111
64
18
3.5.4.1.6.1
Rx FIFO Blocking Mode
The Rx FIFO blocking mode is configured by RXFnC[FnOM] = 0. This is the default
operation mode for the Rx FIFOs.
When an Rx FIFO full condition is reached (RXFnS[FnPI] = RXFnS[FnGI]), no further
messages are written to the corresponding Rx FIFO until at least one message has been
read out and the Rx FIFO Get Index has been incremented. An Rx FIFO full condition is
signalled by RXFnS[FnF] = 1. In addition interrupt flag IR[RFnF] is set.
In case a message is received while the corresponding Rx FIFO is full, this message is
discarded and the message lost condition is signalled by RXFnS[RFnL] = 1. In addition
interrupt flag IR[RFnL] is set.
3.5.4.1.6.2
Rx FIFO Overwrite Mode
The Rx FIFO overwrite mode is configured by RXFnC[FnOM] = 1.
When an Rx FIFO full condition (RXFnS[FnPI] = RXFnS[FnGI]) is signalled by
RXFnS[FnF] = 1, the next message accepted for the FIFO will overwrite the oldest FIFO
message. Put and get index are both incremented by one.
When an Rx FIFO is operated in overwrite mode and an Rx FIFO full condition is
signalled, reading of the Rx FIFO elements should start at least at get index + 1. The
reason for that is, that it might happen, that a received message is written to the Message
RAM (put index) while the CPU is reading from the Message RAM (get index). In this
case inconsistent data may be read from the respective Rx FIFO element. Adding an
offset to the get index when reading from the Rx FIFO avoids this problem. The offset
depends on how fast the CPU accesses the Rx FIFO. The following figure shows an
offset of two with respect to the get index when reading the Rx FIFO. In this case the two
messages stored in element 1 and 2 are lost.
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Rx FIFO Full
Rx FIFO Overwrite
(RXFnS.FnF = ‘1’)
(RXFnS.FnF = ‘1’)
RXFnS.FnPI
= RXFnS.FnGI
7
element 0 overwritten
7
0
6
1
6
1
5
2
5
2
4
4
3
RXFnS.FnPI
= RXFnS.FnGI
0
3
read Get Index + 2
Figure 3-56. Rx FIFO Overflow Handling
After reading from the Rx FIFO, the number of the last element read has to be written to
the Rx FIFO Acknowledge Index RXFnA[FnA]. This increments the get index to that
element number. In case the put index has not been incremented to this Rx FIFO element,
the Rx FIFO full condition is reset (RXFnS[FnF] = 0).
3.5.4.1.7
Dedicated Rx Buffers
The M_CAN supports up to 64 dedicated Rx Buffers. The start address of the dedicated
Rx Buffer section is configured via RXBC[RBSA].
For each Rx Buffer a Standard or Extended Message ID Filter Element with SFEC /
EFEC = 111 and SFID2 / EFID2[10:9] = 00 has to be configured.
After a received message has been accepted by a filter element, the message is stored into
the Rx Buffer in the Message RAM referenced by the filter element. The format is the
same as for an Rx FIFO element. In addition the flag IR[DRX] (Message stored in
Dedicated Rx Buffer) in the interrupt register is set.
Table 3-60. Example Filter Configuration for Rx buffers
Filter Element
SFID1[10:0] EFID1[28:0]
SFID2[10:9] EFID2[10:9]
SFID2[5:0] EFID2[5:0]
0
ID message 1
00
00 0000
1
ID message 2
00
00 0001
2
ID message 3
00
00 0010
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Functional Description
After the last word of a matching received message has been written to the Message
RAM, the respective New Data flag in register NDAT1,2 is set. As long as the New Data
flag is set, the respective Rx Buffer is locked against updates from received matching
frames. The New Data flags have to be reset by the Host by writing a 1 to the respective
bit position.
While an Rx Buffer’s New Data flag is set, a Message ID Filter Element referencing this
specific Rx Buffer will not match, causing the acceptance filtering to continue. Following
Message ID Filter Elements may cause the received message to be stored into another Rx
Buffer, or into an Rx FIFO, or the message may be rejected, depending on filter
configuration
3.5.4.1.7.1
•
•
•
•
Rx Buffer Handling
Reset interrupt flag IR[DRX]
Read New Data registers
Read messages from Message RAM
Reset New Data flags of processed messages
3.5.4.1.8
Debug on CAN Support
Debug messages are stored into Rx Buffers. For debug handling three consecutive Rx
buffers (e.g. #61, #62, #63) have to be used for storage of debug messages A, B, and C.
The format is the same as for an Rx Buffer or an Rx FIFO element.
Advantage: Fixed start address for the DMA transfers (relative to RXBC[RBSA]), no
additional configuration required.
For filtering of debug messages Standard / Extended Filter Elements with SFEC / EFEC
= 111 have to be set up. Messages matching these filter elements are stored into the Rx
Buffers addressed by SFID2 / EFID2[5:0].
After message C has been stored, the DMA request output m_can_dma_req is activated
and the three messages can be read from the Message RAM under DMA control. The
RAM words holding the debug messages will not be changed by the M_CAN while
m_can_dma_req is activated. The behaviour is similar to that of an Rx Buffers with its
New Data flag set.
After the DMA has completed the DMA unit sets m_can_dma_ack. This resets
m_can_dma_req. Now the M_CAN is prepared to receive the next set of debug
messages.
NOTE
To use full ‘Debug on CAN Support’ feature on a M_CAN
instance, a DMA channel is required. Refer to device DMA
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map, to see which M_CAN instances has been assigned with
DMA channel.
3.5.4.1.8.1
Filtering for Debug Messages
Filtering for debug messages is done by configuring one Standard / Extended Message ID
Filter Element for each of the three debug messages. To enable a filter element to filter
for debug messages SFEC / EFEC has to be programmed to 111. In this case fields
SFID1 / SFID2 and EFID1 / EFID2 have a different meaning. While SFID2 /
EFID2[10:9] controls the debug message handling state machine, SFID2 / EFID2[5:0]
controls the location for storage of a received debug message.
When a debug message is stored, neither the respective New Data flag nor IR[DRX] are
set. The reception of debug messages can be monitored via RXF1S[DMS].
Table 3-61. Example Filter Configuration for Debug Messages
Filter Element
SFID1[10:0] EFID1[28:0]
SFID2[10:9] EFID2[10:9]
SFID2[5:0] EFID2[5:0]
0
ID debug message A
01
11 1101
1
ID debug message B
10
11 1110
2
ID debug message C
11
11 1111
3.5.4.1.8.2
Debug Message Handling
The debug message handling state machine assures that debug messages are stored to
three consecutive Rx Buffers in correct order. In case of missing messages the process is
restarted. The DMA request is activated only when all three debug messages A, B, C
have been received in correct order.
The status of the debug message handling state machine is signaled via RXF1S[DMS].
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Functional Description
.
HW reset or
Init state
T0
DMS = 00
T8
T1
T7
T2
T3
DMS = 11
DMS = 01
T5
T4
T6
DMS = 10
Figure 3-57. Debug Message Handling State Machine
T0: reset m_can_dma_req output, enable reception of debug messages A, B, and C
T1: reception of debug message A
T2: reception of debug message A
T3: reception of debug message C
T4: reception of debug message B
T5: reception of debug messages A, B
T6: reception of debug message C
T7: DMA transfer completed
T8: reception of debug message A,B,C (message rejected)
3.5.5 Tx Handling
The Tx Handler handles transmission requests for the dedicated Tx Buffers, the Tx FIFO,
and the Tx Queue. It controls the transfer of transmit messages to the CAN Core, the Put
and Get Indices, and the Tx Event FIFO. Up to 32 Tx Buffers can be set up for message
transmission. The Tx Buffer element is described in Tx Buffer Element.
Note
AUTOSAR requires at least three Tx Queue Buffers and
support of transmit cancellation.
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The Tx Handler starts a Tx scan to check for the highest priority pending Tx request (Tx
Buffer with lowest Message ID) when the Tx Buffer Request Pending register TXBRP is
updated, or when a transmission has been started.
3.5.5.1 Transmit Pause
The transmit pause feature is intended for use in CAN systems where the CAN message
identifiers are (permanently) specified to specific values and cannot easily be changed.
These message identifiers may have a higher CAN arbitration priority than other defined
messages, while in a specific application their relative arbitration priority should be
inverse. This may lead to a case where one ECU sends a burst of CAN messages that
cause another ECU’s CAN messages to be delayed because that other messages have a
lower CAN arbitration priority.
If, for example, CAN ECU-1 has the transmit pause feature enabled and is requested by
its application software to transmit four messages, it will, after the first successful
message transmission, wait for two CAN bit times of bus idle before it is allowed to start
the next requested message. If there are other ECUs with pending messages, those
messages are started in the idle time, they would not need to arbitrate with the next
message of ECU-1. After having received a message, ECU-1 is allowed to start its next
transmission as soon as the received message releases the CAN bus.
The transmit pause feature is controlled by bit CCCR.TXP. If the bit is set, the M_CAN
will, each time it has successfully transmitted a message, pause for two CAN bit times
before starting the next transmission. This enables other CAN nodes in the network to
transmit messages even if their messages have lower prior identifiers. Default is transmit
pause disabled (CCCR[TXP] = 0).
This feature looses up burst transmissions coming from a single node and it protects
against “babbling idiot” scenarios where the application program erroneously requests
too many transmissions.
3.5.5.2 Dedicated Tx Buffers
Dedicated Tx Buffers are intended for message transmission under complete control of
the Host CPU. Each Dedicated Tx Buffer is configured with a specific Message ID. In
case that multiple Tx Buffers are configured with the same Message ID, the Tx Buffer
with the lowest buffer number is transmitted first.
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Functional Description
If the data section has been updated, a transmission is requested by an Add Request via
TXBAR[ARn]. The requested messages arbitrate internally with messages from an
optional Tx FIFO or Tx Queue and externally with messages on the CAN bus, and are
sent out according to their Message ID.
A Dedicated Tx Buffer allocates Element Size 32-bit words in the Message RAM (see the
following table). Therefore the start address of a Dedicated Tx Buffer in the Message
RAM is calculated by adding transmit buffer index (0…31) x Element Size to the Tx
Buffer Start Address TXBC[TBSA].
Table 3-62. Tx Buffer / FIFO / Queue Element Size
TXESC.TBDS[2:0]
Data Field [bytes]
Element Size [RAM words]
000
8
4
001
12
5
010
16
6
011
20
7
100
24
8
101
32
10
110
48
14
111
64
18
3.5.5.3 Tx FIFO
Tx FIFO operation is configured by programming TXBC[TFQM] to 0. Messages stored
in the Tx FIFO are transmitted starting with the message referenced by the Get Index
TXFQS[TFGI]. After each transmission the Get Index is incremented cyclically until the
Tx FIFO is empty. The Tx FIFO enables transmission of messages with the same
Message ID from different Tx Buffers in the order these messages have been written to
the Tx FIFO. The M_CAN calculates the Tx FIFO Free Level TXFQS[TFFL] as
difference between Get and Put Index. It indicates the number of available (free) Tx
FIFO elements.
New transmit messages have to be written to the Tx FIFO starting with the Tx Buffer
referenced by the Put Index TXFQS[TFQPI]. An Add Request increments the Put Index
to the next free Tx FIFO element. When the Put Index reaches the Get Index, Tx FIFO
Full (TXFQS[TFQF] = 1) is signalled. In this case no further messages should be written
to the Tx FIFO until the next message has been transmitted and the Get Index has been
incremented.
When a single message is added to the Tx FIFO, the transmission is requested by writing
a 1 to the TXBAR bit related to the Tx Buffer referenced by the Tx FIFO's Put Index.
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When multiple (n) messages are added to the Tx FIFO, they are written to n consecutive
Tx Buffers starting with the Put Index. The transmissions are then requested via TXBAR.
The Put Index is then cyclically incremented by n. The number of requested Tx buffers
should not exceed the number of free Tx Buffers as indicated by the Tx FIFO Free Level.
When a transmission request for the Tx Buffer referenced by the Get Index is cancelled,
the Get Index is incremented to the next Tx Buffer with pending transmission request and
the Tx FIFO Free Level is recalculated. When transmission cancellation is applied to any
other Tx Buffer, the Get Index and the FIFO Free Level remain unchanged.
A Tx FIFO element allocates Element Size 32-bit words in the Message RAM. Therefore
the start address of the next available (free) Tx FIFO Buffer is calculated by adding Tx
FIFO/Queue Put Index TXFQS.TFQPI (0…31) x Element Size to the Tx Buffer Start
Address TXBC[TBSA].
3.5.5.4 Tx Queue
Tx Queue operation is configured by programming TXBC[TFQM] to 1. Messages stored
in the Tx Queue are transmitted starting with the message with the lowest Message ID
(highest priority). In case that multiple Queue Buffers are configured with the same
Message ID, the Queue Buffer with the lowest buffer number is transmitted first.
New messages have to be written to the Tx Buffer referenced by the Put Index
TXFQS[TFQPI]. An Add Request cyclically increments the Put Index to the next free Tx
Buffer. In case that the Tx Queue is full (TXFQS[TFQF] = 1), the Put Index is not valid
and no further message should be written to the Tx Queue until at least one of the
requested messages has been sent out or a pending transmission request has been
cancelled.
The application may use register TXBRP instead of the Put Index and may place
messages to any Tx Buffer without pending transmission request.
A Tx Queue Buffer allocates Element Size 32-bit words in the Message RAM. Therefore
the start address of the next available (free) Tx Queue Buffer is calculated by adding Tx
FIFO/Queue Put Index TXFQS[TFQPI] (0…31) x Element Size to the Tx Buffer Start
Address TXBC[TBSA].
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Functional Description
3.5.5.5 Mixed Dedicated Tx Buffers / Tx FIFO
In this case the Tx Buffers section in the Message RAM is subdivided into a set of
Dedicated Tx Buffers and a Tx FIFO. The number of Dedicated Tx Buffers is configured
by TXBC[NDTB]. The number of Tx Buffers assigned to the Tx FIFO is configured by
TXBC[TFQS]. In case TXBC[TFQS] is programmed to zero, only Dedicated Tx Buffers
are used.
Tx FIFO
Dedicated Tx Buffers
Buffer Index
Tx Sequence
4
5
ID15
ID8
5.
4.
0
1
ID3
1.
2
3
6
9
7
8
ID24
ID4
ID2
6.
2.
3.
Put Index
Get Index
Figure 3-58. Example of mixed Configuration Dedicated Tx Buffers / Tx FIFO
Tx prioritization:
• Scan Dedicated Tx Buffers and oldest pending Tx FIFO Buffer (referenced by
TXFS[TFGI])
• Buffer with lowest Message ID gets highest priority and is transmitted next
3.5.5.6 Mixed Dedicated Tx Buffers / Tx Queue
In this case the Tx Buffers section in the Message RAM is subdivided into a set of
Dedicated Tx Buffers and a Tx Queue. The number of Dedicated Tx Buffers is
configured by TXBC.NDTB. The number of Tx Queue Buffers is configured by
TXBC.TFQS. In case TXBC.TFQS is programmed to zero, only Dedicated Tx Buffers
are used.
Tx Queue
Dedicated Tx Buffers
Buffer Index
Tx Sequence
0
1
ID3
2.
2
7
8
ID24
ID4
ID2
6.
3.
1.
4
5
ID15
ID8
5.
4.
3
6
9
Put Index
Figure 3-59. Example of mixed Configuration Dedicated Tx Buffers / Tx Queue
Tx prioritization:
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Chapter 3 Modular CAN (M_CAN)
• Scan all Tx Buffers with activated transmission request
• Tx Buffer with lowest Message ID gets highest priority and is transmitted next
3.5.5.7 Transmit Cancellation
The M_CAN supports transmit cancellation. This feature is especially intended for
gateway applications and AUTOSAR based applications. To cancel a requested
transmission from a dedicated Tx Buffer or a Tx Queue Buffer the Host has to write a 1
to the corresponding bit position (= number of Tx Buffer) of register TXBCR. Transmit
cancellation is not intended for Tx FIFO operation.
Successful cancellation is signalled by setting the corresponding bit of register TXBCF to
1.
In case a transmit cancellation is requested while a transmission from a Tx Buffer is
already ongoing, the corresponding TXBRP bit remains set as long as the transmission is
in progress. If the transmission was successful, the corresponding TXBTO and TXBCF
bits are set. If the transmission was not successful, it is not repeated and only the
corresponding TXBCF bit is set.
Note
In case a pending transmission is cancelled immediately before
this transmission could have been started, there follows a short
time window where no transmission is started even if another
message is also pending in this node. This may enable another
node to transmit a message which may have a lower priority
than the second message in this node.
3.5.5.8 Tx Event Handling
To support Tx event handling the M_CAN has implemented a Tx Event FIFO. After the
M_CAN has transmitted a message on the CAN bus, Message ID and timestamp are
stored in a Tx Event FIFO element. To link a Tx event to a Tx Event FIFO element, the
Message Marker from the transmitted Tx Buffer is copied into the Tx Event FIFO
element.
The Tx Event FIFO can be configured to a maximum of 32 elements. The Tx Event FIFO
element is described in Tx Event FIFO Element.
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Functional Description
When a Tx Event FIFO full condition is signalled by IR[TEFF], no further elements are
written to the Tx Event FIFO until at least one element has been read out and the Tx
Event FIFO Get Index has been incremented. In case a Tx event occurs while the Tx
Event FIFO is full, this event is discarded and interrupt flag IR[TEFL] is set.
To avoid a Tx Event FIFO overflow, the Tx Event FIFO watermark can be used. When
the Tx Event FIFO fill level reaches the Tx Event FIFO watermark configured by
TXEFC[EFWM], interrupt flag IR[TEFW] is set.
When reading from the Tx Event FIFO, two times the Tx Event FIFO Get Index
TXEFS[EFGI] has to be added to the Tx Event FIFO start address TXEFC[EFSA].
3.5.6 FIFO Acknowledge Handling
The Get Indices of Rx FIFO 0, Rx FIFO 1, and the Tx Event FIFO are controlled by
writing to the corresponding FIFO Acknowledge Index (see the registers RXF0A ,
RXF1A, and TXEFA). Writing to the FIFO Acknowledge Index will set the FIFO Get
Index to the FIFO Acknowledge Index plus one and thereby updates the FIFO Fill Level.
There are two use cases:
• When only a single element has been read from the FIFO (the one being pointed to
by the Get Index), this Get Index value is written to the FIFO Acknowledge Index.
• When a sequence of elements has been read from the FIFO, it is sufficient to write
the FIFO Acknowledge Index only once at the end of that read sequence (value:
Index of the last element read), to update the FIFO's Get Index.
Due to the fact that the CPU has free access to the M_CAN's Message RAM, special care
has to be taken when reading FIFO elements in an arbitrary order (Get Index not
considered). This might be useful when reading a High Priority Message from one of the
two Rx FIFOs. In this case the FIFO's Acknowledge Index should not be written because
this would set the Get Index to a wrong position and also alters the FIFO's Fill Level. In
this case some of the older FIFO elements would be lost.
Note
The application has to ensure that a valid value is written to the
FIFO Acknowledge Index. The M_CAN does not check for
erroneous values.
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Chapter 3 Modular CAN (M_CAN)
3.5.7 Interface to DMA Controller
When all three debug messages A, B, C have been received in the correct order, M_CAN
DMA request signal is activated to trigger a DMA transfer. The RAM words holding
debug messages A, B, C will not be changed by the M_CAN while M_CAN DMA
request signal is active.
After the transfer of the received messages has completed the DMA unit activates the
M_CAN DMA acknowledge signal. This resets M_CAN DMA request signal. The debug
message handling state machine enters idle state (DMS = 00) and waits for reception of
the next debug messages.
NOTE
If the DMA unit activates the M_CAN DMA acknowledge
signal before the DMA transfer has completed, the Rx Buffer
elements holding debug messages A, B, C are unlocked and
may be overwritten by received debug messages.
M_CAN host clk
M_CAN DMA request
M_CAN DMA acknowledge
Figure 3-60. Timing of DMA Interface Signals
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Functional Description
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Document Number MPC5777CRMAD
Revision 1, 12/2015