AP32300 - XMC4000 - Controller Area Network Controller(MultiCAN)

XMC 4000
32-bit Microcontroller Series for Industrial Applications
Control ler A rea Network Control ler
(Mul tiCA N)
AP32300
Application Note
XMC 4000
32-bit
Microcontroller
Series for Industrial Applications
About
this document
Control
ler A rea Network Control ler
The Infineon MultiCAN module contains independently operating CAN nodes with full-CAN functionality to
meet
the ISO11898_1
standard.
(Mul
tiCA N)
Scope and purpose
This document combines a brief overview of the MultiCAN module in the XMC4000 family with a more
AP32300
detailed operation description of different features, such as:

FIFO

Gateway

Baudrate detection
Note: Depending on the configuration of each microcontroller derivative which includes the MultiCAN module,
the number of nodes and message objects might be different.
Applicable Products

XMC4000 Microcontroller Family
References
The example code “AP32300_XMC4000_MultiCAN_SW” can be downloaded from www.infineon.com/XMC.
For Application Kits and DAVE™, please refer to www.infineon.com/xmc-dev.
V1.0
1
2015-07
Controller Area Network Controller (MultiCAN)
AP32300
Table of Contents
Table of Contents
About this document .....................................................................................................................1
Table of Contents ..........................................................................................................................2
1
1.1
1.2
1.3
CAN protocol and the Infineon CAN module .....................................................................3
Typical CAN node structure ................................................................................................................ 5
CAN frame format ................................................................................................................................ 5
CAN node station ................................................................................................................................. 6
2
2.1
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
2.1.6
2.1.7
2.2
2.3
2.3.1
2.3.2
2.3.3
2.4
2.4.1
2.4.2
2.4.3
2.4.4
MultiCAN in the XMC4000 family .....................................................................................7
MultiCAN structure .............................................................................................................................. 7
Node Control Unit ......................................................................................................................... 8
The Linked List Controller........................................................................................................... 10
The Interrupt Control Unit .......................................................................................................... 11
Node Receive input selection ..................................................................................................... 12
Message controller ...................................................................................................................... 12
Interfaces and interconnects ...................................................................................................... 12
Bit timing ..................................................................................................................................... 14
Hardwaer handling of CAN frame reception and transmission ....................................................... 16
Programming the MultiCAN module ................................................................................................ 17
Software initialization of MultiCAN ............................................................................................ 17
Software handling on CAN node ................................................................................................ 18
Software control of a message transfer ..................................................................................... 19
MultiCAN special features ................................................................................................................. 22
Loop-back mode ......................................................................................................................... 22
CAN analyzer mode ..................................................................................................................... 22
MultiCAN FIFO ............................................................................................................................. 22
MultiCAN Gateway....................................................................................................................... 24
3
3.1
3.2
3.3
3.4
3.5
3.6
3.7
Implementing the example .......................................................................................... 27
First steps .......................................................................................................................................... 27
Example_1: Standard Message Object Transmission and Receive ................................................. 27
Example_2: Using Receive FIFO ........................................................................................................ 27
Example_3: Using Transmit FIFO ...................................................................................................... 27
Example_4: Using Gateway without FIFO ........................................................................................ 27
Example_5: Using Gateway with FIFO .............................................................................................. 28
Example_6: Baudrate detection ....................................................................................................... 28
4
Running example code ................................................................................................ 30
5
5.1
DAVE™ and XMCLib ...................................................................................................... 32
Implementation with XMCLib ........................................................................................................... 32
6
6.1
Appendix .................................................................................................................... 34
Kit information .................................................................................................................................. 34
7
Revision History .......................................................................................................... 35
Application Note
2
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
CAN protocol and the Infineon CAN module
1
CAN protocol and the Infineon CAN module
CAN is a multi-master bus system with broadcasting capability. In the CAN protocol, the bus nodes do not
have a specific address. Instead, the address information is contained in the identifiers of the transmitted
messages, indicating the message content and the priority of the message for arbitration.
CAN is a low cost protocol for real-time applications with a high reliability. Nodes can be easily connected or
disconnected without disturbing the communication of the other nodes.
Uses
The CAN bus is most widely used in the automotive and industrial market segments:

CAN is used in the automotive industry to enable data exchange between ECUs over the complete car.

CAN is used in industrial automation to connect control units, sensors, and actuators for example. There
are several CAN-based high-layer protocols, including DeviceNet, CANopen, and J1939, which are
internationally standardized and their networks are used in width application fields.

CAN is used for initialization, program and parameter up-/download, exchange of rated values / actual
values, and diagnosis for example, in end-of-line or on-the-fly of software updates.
CAN protocol specification and history

2.0A; specify "Standard CAN" - 11 bit message ID’s, total 2048 ID’s available.

2.0B; specify “Extended CAN” – 29 bit message ID’s, more than 536 million ID’s available.

ISO11898-1 as successor of 2.0B.

TTCAN: Time-triggered communication on CAN.

CAN FD integration into ISO11898-1.
Application Note
3
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
CAN protocol and the Infineon CAN module
Table 1
Infineon CAN implementations
Module name
TwinCAN
Devices
Nodes
Message
objects
FIFO/
Gateway
TTCAN
CAN FD
XC16x
2
32
yes
-
-
MultiCAN
32 message objects can be individually assigned to one of the two CAN nodes.
FIFO participate in a 2, 4, 8, 16, 32 buffer.
Analyzer Mode.
XC800
XC2000/XE166
XMC4000
TriCore
-
Max. 8
Max. 256
(flexible
assigned)
yes
on certain
devices
-
Message objects can be individually/dynamically assigned to one of the CAN nodes.
FIFO/Gateway buffer size is programmable.
Analyzer mode and bit timing mode.
Note: The number of nodes, message objects and TTCAN features of MultiCAN module in
each device are varied. For details please refer to the appropriate Data Sheet.
MultiCAN+
AURIX
-
Application Note
Max. 8
Max. 256
(flexible
assigned)
yes
on certain
devices
yes
ISO CAN FD
4
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Controller Area Network Controller (MultiCAN)
AP32300
CAN protocol and the Infineon CAN module
1.1
Typical CAN node structure
CAN_H
CAN-Bus
Udiff
CAN_L
CAN-Transceiver
Physical layer
Tx
Controller
Rx
CAN
module
CAN
module
XMC
XE166
Data link layer
e.g.
ECU
Application
Figure 1
e.g.
sensors
application layer
Typical CAN node structure
CAN is insensitive to electromagnetic interference. The maximum CAN bus speed is 1 MBaud, which can be
achieved with a bus length of up to 40 meters when using a twisted pair wire.
1.2
CAN frame format
SOF
RTR
0
11_ID Data
11_ID
0
SOF
11_ID Remote
RTR
0
11_ID
1
IDE
0
ACK
0 DLC_4
bytes
IDE
0
CRC_15 1
0
EOF_7
1
IFS_3
idle
ACK
0 DLC_4 CRC_15 1
0
1
EOF_7
IFS_3
idle
IFS: interframe space
SRR
SOF
0
29_ID Data
11_ID
1
SOF
29_ID Remote
SRR
0
11_ID
transfer
Error frames
1
IDE
RTR
1
18_ID
0
IDE
ACK
0
0
DLC_4
0
0
DLC_4 CRC_15 1
RTR
1
18_ID
6 to 12 bits
8 bits
Error flag field
Error delimiter
field
1
IFS
6 bits
0..6
bits
Overload flag +
Superimpositon of
active oveload flag
Figure 2
8 bits
CRC_15 1
0
1
EOF_7
IFS_3
idle
ACK
IFS
transfer
Error frame of „error active“ node
Overload frame
bytes
0
1
EOF_7
IFS_3
6 bits
8 bits
Error flag field
Error delimiter
field
idle
IFS
Error frame of „error passive“ node
IFS
Error delimiter
field
CAN frame formats (Data, Remote, Error, Overload frame)
Application Note
5
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
CAN protocol and the Infineon CAN module
1.3

CAN node station
Each CAN node can enter one of three error states , according to the value of their internal error
counters:
− error active
− error passive
− bus off

Each CAN node implements one receive and one transmit error counter. Counting increases or decreases
according to ISO 11898-1.

The error-active state is the usual state after reset. The bus node can then receive and transmit messages
and transmit active Error Frames (made of dominant bits) without any restrictions. An ‘error-active’ node
may access the bus as soon as the bus is free.

In the error-passive state, messages can still be received and transmitted, although, after transmission of
a message the node must suspend transmission. It must wait 8 bit times longer than error-active nodes
before it may transmit another message. In terms of error signaling, only passive Error Frames (made of
recessive bits) may be transmitted by an error-passive node.

In the bus-off state it is temporarily impossible for the node to participate in the bus communication.
During this state, messages can be neither received nor transmitted.
REC
128
Error active
REC>127 or
TEC>127
REC<128 and
TEC<128
error active
Restart request and 128 occurrences
of 11 consecute „1" bits
error passive
TEC
256
Error passive
Bus off
128
TEC>255
error active
Figure 3
error passive
Bus off
CAN node stations (Error active, Error passive, Bus off)
Application Note
6
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
2
MultiCAN in the XMC4000 family
The MultiCAN module in the XMC4000 family supports the following functionality:

Compliant with classical CAN as defined in ISO 11898-1.

Baudrate programmable for each node.

FIFO/Gateway functionality.

Acceptance mask filtering for each MO.

Frame counter of each CAN node is selectable for frame count, the time stamp, or the bit timing mode.

Freely assignable interrupt sources to interrupt nodes. 8 interrupt output lines are available.

Prioritization of message objects on ID or list number.
Table 2
XMC4000 derivatives with MultiCAN implementation (Refer also to Data Sheet)
Derivative Package
Nodes
(max.)
Message Objects
(max.)
Max. fCAN (fCLC)= fPERIPH Module Address Space
XMC4500
PG-LFBGA-144
PG-LQFP-144
PG-LQFP-100
3
64
120MHz
XMC440x
PG-LQFP-100
PG-LQFP-64
2
64
120MHz
XMC4200
XMC4100
PG-LQFP-64
PG-VQFN-48
2
64
80MHz
XMC4108
PG-LQFP-64
PG-VQFN-48
1
32
80MHz
2.1
MultiCAN structure
4801 4000H - 4801 7FFFH
The MultiCAN module consists of:

Node Control Unit.

The Linked ListController.

The Interrupt Control Unit.

Node Receive Input Selection.

Message Controller.

Interfaces and Interconnects.
Application Note
7
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
2.1.1
Node Control Unit
Each CAN node consists of several sub-units:

Bitstream processor.
− Performs data, remote, error, and overload frame processing according to the ISO 11898 standard.
− It checks bus idle, adds SOF and EOF, controls the CRC generation and arbitration procedure, and
monitors ACK slot. If an error mismatch is detected an error event is generated in register NSRx.

Error handling unit.
− Performs Tx/Rx error counter and sets node into an error-active/-passive and bus-off state according
to the ISO 11898 standard.

Bit timing unit.
− For baudrate detection and resynchronization.

Node control bits.
− To enable/disable CAN transfer on this node.

Interrupt control unit.
− For node-specific events.
Node control register NCRx (x=0, 1, 2)

INIT (‘wrh’)
− Set by hardware when the CAN node enters the bus-off state.
− It is cleared by software to enable the participation of the node in the CAN traffic.

CCE (Configuration Change Enable).
− Register NBCTRx, NECNTx, and NPCRx can be written to only when CCE=1.
Node status register NSRx (x=0, 1, 2)

ALERT (alert warning). An ALERT is set when:
− A change of bit NSRx.BOFF.
− A change of bit NSRx.EWRN.
− A List Length Error, which also sets bit NSRx.LLE.
− A List Object Error, which also sets bit NSRx.LOE.
Note: Flag ALERT must be reset by software (write 0).

EWRN and BOFF (Bus-off).
− Both are ‘rh’ bits.
− They are updated by hardware.
Application Note
8
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
Bus-off recovery
REC is used to count 128x bus-idle (11x recessive bit)
BOFF=0
ERW=0
TEC>=0x60 or
REC>=0x60
TEC<0x60 &
REC<0x60
BOFF=0
ERW=1
TEC>0xFF
BOFF=1
ERW=0
INIT=1
REC>=0x60
REC=1
TEC=1 by HW
Figure 4
BOFF=1
ERW=1
REC>0x80
BOFF=0
ERW=0
REC=0
TEC=0 by HW
Status flags changing of MultiCAN register NSR
Bus-off state and INIT state
According to the CAN specification, in MultiCAN the bus-off state is activated if the Transmit Error Counter
equals or exceeds the busoff limit of 256. This state is reported by flag BOFF.
“Bus-off recovery sequence” is started automatically when the CAN mode is in the bus-off state. Figure 4
shows CAN node states changing in MultiCAN.

During the bus-off-state, all respective control and message object registers hold their current values
and the error counters are reset.

128 bus-idle events (11 consecutive ‘recessive’ bits) have to be detected, before the synchronization
sequence can be initiated. The monitoring of the bus idle events is immediately started by hardware
after entering the bus-off state. The number of already detected bus-idle events is counted and indicated
by the receive error counter. After completion of the bus-off recovery sequence, the MultiCAN clears the
bit BOFF, while INIT and ALERT will remain set.

After 128 bus-idle events bit INIT will be tested by hardware.
− If INIT is still set, the affected CAN node controller waits until INIT is cleared and at least one bus-idle
event is detected on the CAN bus, before the node takes part in CAN traffic again; for example
MultiCAN enters 'power-on' state.
− If INIT has been already cleared (software has reset INIT during or after the recovery phase), the
message transfer between the affected CAN node controller and its associated CAN bus is immediately
enabled; for example MultiCAN enters 'idle' state.
Application Note
9
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
2.1.2
The Linked List Controller
The message objects are organized in double-chained lists. The list organized message objects benefit from
a flexible allocation of message objects for their CAN node.
CAN node 0
PPREV=5
MO5 PNEXT=11
List=1
PPREV=5
MO11 PNEXT=9
List=1
CAN node 1
CAN node 2
Unallocated
MSGs
1. MO in List 2
1. MO in List 3
1. MO in List 0
2. MO in List 2
2. MO in List 3
2. MO in List 0
last MO in List 2
last MO in List 3
n. MO in List 0
PPREV=11
MO9 PNEXT=9
List=1
SIZE=3
BEGIN=5
END=9
Register LIST 1
Figure 5
List 3 is only in
XMC4500
The Linked List

FIFO and gateway message objects are based on a list structure.

After reset, all message objects are on the list (list 0) of unallocated elements.

After each write operation the bit PANCTR.BUSY must be checked in order to ensure correct list pointers
in each message object.
Application Note
10
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
2.1.3
The Interrupt Control Unit
The ICU controls the interrupt generation for different conditions. There are 140 hardware interrupt events.

CAN node interrupts
− Each CAN node has 4 interrupt sources (alert, last error, Tx/Rx ok, CFC overflow).

Message object interrupts
− Each message object has 2 interrupt sources (TxOk and RxOk).
MultiCAN contains 8 interrupt output lines (INT_O0…7), which are assigned to the NVIC (CAN.SR0…SR7).
Table 3
MultiCAN interrupts
Flag
Enabled by
SRx selected by Flag to be cleared
by software
Indication
NSRx.TXOK
NCRx.TRIE
NIPRx.TRINP
NSRx.TXOK=0
Frame has been transmitted on
the CAN node.
NSRx.RXOK
NCRx.TRIE
NIPRx.TRINP
NSRx.RXOK=0
Frame has been successflly
understood by the CAN node.
NSRx.ALERT
NCRx.ALIE
NIPRx.ALINP
NSRx.ALERT=0
Alert warning.
NSRx.BOFF
-
-
only by HW
NSRx.EWRN
-
-
only by HW
Rx/Tx level limit error.
NSRx.LLE
-
-
NSRx. LLE=0
List length error.
NSRx.LOE
-
-
NSRx.LOE=0
List object error.
SRx.LEC
NCRx.LECIE
NIPRx.LECINP
Only by HW.
Any write to LEC
will result in a 0x7
Last error code change has
been updated.
NFCRx.CFCOV
NFCRx.CFCIE
NIPRx.CFCINP
NFCRx.CFCOV=0
Frame counter overflow
interrupt.
CAN frame counter mode:
- Frame count mode.
- Time stamp mode.
- Bit timing mode.
MOSTATn.RXPND MOFCRn.RXIE
MOIPRn.RXINP
MOCTRn=0x1
Frame has been received in the
MO.
MOSTATn.TXPND MOFCRn.TXIE
MOIPRn.TXINP
MOCTRn=0x2
Frame has been transmitted
from the MO.
CAN node
Message Object
Application Note
11
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
2.1.4
Node Receive input selection
The MultiCAN module contains a switch in order to select different node’s receive input lines via the Node
Port Control Register NPCRx (x=0, 1, 2). The selected input signal for each CAN node is made available by its
internal signal CANxINS, which is connected to other peripherals.

Select the input line via bit field NPCRx.RXSEL.

LBM=1: loop-back mode.

Internal signal CANxINS is connected to other peripherals (USIC), but it can not trigger ERU directly.
Note: In the XMC4000 family the intenal signal CANxINS can not trigger ERU directly. Instead, the defined CAN
input pin triggers ERU directly.
Figure 6
2.1.5
Node input control registers
Message controller
The Message controller handles CAN frames between the node and the message RAM. It performs the
following functions:

Receive acceptance filtering for storing the CAN frame received on the node into the message object.

Transmit acceptance filtering for detection and prioritization of the message object to be transmitted.

FIFO and gateway functionality.
2.1.6
Interfaces and interconnects
The MultiCAN module interfaces with the clock, port, and interrupt/DMA connections are described here.
Clock input
Clock fPERIPH from the XMC4000 Clock Control Unit (CCU) is used as the MultiCAN module clock input. In the
XMC4000 family all peripherals can be individually controlled via the registers PRSETx/PRCLRx.
After power-on-reset, MultiCAN module clocked with fPERIPH will remain in a reset state. To release MultiCAN,
PRCLR1.MCAN0RS must be set to 1.
fCLC is used for internal logic and register operation.
fCAN is used baud rate generation.
In order to get a maximum of accesses to the MultiCAN module the fCLC = fPERIPH should use the maximum fPLL.
Application Note
12
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
fOSCHP
XMC
clock control unit (CCU) à fPLL
fPERIPH
Clock control
CAN_CLC
fCLC
Fractional divider
CAN_FDR
fCAN
Baud rate
XMC
Peripheral reset control
Via bit MCAN0RS (bit 4) in
register PRSET1/PRCLR1
Module registers
XMC
Peripheral clock gating control
Via bit MCAN0 (bit 4) in
register CGATCLR1/CGATSET1
(not available in XMC4500 )
Figure 7
MultiCAN
MultiCAN clock generation
Interrupt trigger (to DMA, to other peripherals, to Interrupt Control Unit)

CAN.SR0 through to SR7 (IRQ number 76...83).
− CAN.SR0 through to SR3 can be used for DMA service.

The interrupt priority level and enable/disable are controlled by the NVIC unit in the XMC family.
Port pin and I/O lines control
The interconnections between the MultiCAN and the port I/O port lines are controlled in the port logic.
For each CAN node its input receive pin, selected via NPCRx.RXSEL should be initialized as “direct input”
with Pn_IOCRy.PCx=00000B to receive the CAN frame, while the transmit output pin must be configured as
alternate output pin by Pn_IOCRy.PCx=100xxB with push-pull driven mode.
In XMC4000 up to 4 alternate output functions (ALT1/2/3/4) can be mapped to a single port pin. Usually the
MultiCAN transmit output pin uses ALT1/2. (Please refer to the appropriate Reference Manual or Data Sheet).
Application Note
13
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
2.1.7
Bit timing
In the ISO 11898-1 classical CAN part, one CAN bit time is sub-divided into 4 segments and contains 8-25
Time Quanta tq.

Synchronization Segment (TSync= 1×tq)
− Used to synchronize the various CAN nodes on the bus and an edge is expected within this segment.

Propagation Time Segment (TProp= 1 … 8×tq)
− Used to compensate for signal delays of the actual network.

Phase buffer segment (Tb1 = 1 … 8×tq)
− Used to compensate for a mismatch between transmitter and receiver clock phases detected in TSync.
− It may be lengthened by re-synchronization.

Phase buffer segment (Tb2 = 1 … Tb1):
− Same as Tb1.
− It may be shortened by re-synchronization.
The amount of lengthening and shortening of Tb1 and Tb2 is determined by the maximum value given by the
SJW.
tPERIPH
fPERIPH
Fractional divider (FDR.DM and FDR.STEP)
fCAN = fPERIPH if DM=1 and STEP=1023
fCAN
Baudrate Prescaler (BTR.DIV8 and BTR.BPR)
tq = (BRP + 1) / fCAN if DIV8=0
time quanta tq
tq
t
TSeg1 = (TSEG1 + 1) × tq
CAN bit period
Tsync
(fixed)
TSeg2 = (TSEG2 + 1) × tq
Tseg1 (user definable)
Tseg2
(user definable)
Sample Point
TProp
Tb1
Tb2
1 Bit Time
Figure 8
MultiCAN bit timing
Application Note
14
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
The bit rate, the sample point, and SJW are user programmable in MultiCAN.

CAN bit time
− This is subd-ivided into the three, non-overlapping segments TSync, TSeg1 and TSeg2
− TProp and Tb1 are sufficient to TSeg1.
− tq = (BRP + 1) /fCAN (if DIV8=0) or 8 x (BRP + 1) /fCAN (if DIV8=1)
− TSync = 1×tq
− TSeg1 = (TSEG1 + 1)×tq
− TSeg2 = (TSEG2 + 1)×tq
Bit time = TSync + TSeg1 + TSeg2
Sample point = (TSync + TSeg1) / Bit time

The sample point is an important parameter.
− Choosing a later sample point in the bit period results in more tolerance with respect to propagation
delay and therefore greater bus length. Conversely, choosing a sample point closer to the mid-point of
the bit period will allow a greater oscillator tolerance for each node in the system.
− Obviously a large allowable oscillator tolerance and a long bus length are conflicting goals, which can
only be accomplished through optimization of the bit timing parameters. A good general rule is to set
the sample point to about 80% of the bit timing.

The control register BTR is used to set up the bit timing parameters.
− Number of time quanta for SJW (NTsjw): 1 ≤ NTsjw ≤ 4 and NTsjw ≤NTseg2
On the internet you can find possible MultiCAN register values for CAN bit rates (see CAN Bit Time
Calculation). The next table gives some typical bit timing parameters.
Table 4
MultiCAN bit time settings (SJW=1, SP=80%)
Baud Rate
fsys
BRP
Ntq
(8..25)
NTseg1= 1+ (1+TSEG1) NTseg2= (1+TSEG2)
(3..16)
(2..8)
NBTR
1000
120
6
20
1+15
4
0x3E06
8
15
1+11
3
0x2A07
10
10
1+7
2
0x160B
12
20
1+15
4
0x3E0B
16
15
1+11
3
0x2A0F
24
10
1+7
2
0x1617
500
120
Application Note
15
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
2.2
Hardwaer handling of CAN frame reception and transmission
The following figure illustrates the MultiCAN hardware handling of a CAN frame reception and a CAN frame
transmission.
CAN frame reception
Figure 9
CAN frame transmissin
CAN frame reception and transmission by the MultiCAN node
Transmission process
The transmission process of a message object (DIR=’1’ or DIR=’0’) starts after winning the transmit
acceptance filtering.
A message object with the following settings wins an ‘effective transmit request’:

MSGVAL=’1’

TXEN0=’1’

TXEN1=’1’

TXRQ=’1’

PRI != ‘0’
A trigger transmission request in a transmit message object (DIR=’1’) generates a data frame.
A trigger transmission request in a receive message object (DIR=’0’) generates a remote frame.
Application Note
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Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
Reception process
The reception process of a message object (DIR=’0’ or DIR=’1’) starts after winning the receive acceptance
filtering.
A message object is qualified for reception of a frame if the following conditions are fulfilled:

MSGVAL =’1’

RXEN =’1’

DIR=’1’ accepts only remote frame; DIR=’0 accepts only data frame

MIDE=’0’ accepts both 11_IDs and 29_IDs; MIDE =’1’ accepts only its specified IDs via MOARn.IDE

The ID of the message object matches the received ID through the acceptance mask (MOAMRn.AM)

PRI != ‘0’
Incoming remote frames are stored in a corresponding transmit message object (DIR=’1’).
Arriving data frames are saved in a matching receive message object (DIR=’0’).
Resolution of multiple message objects
If several message objects assigned on the CAN node meet the conditions above, the message object with
the highest PRI wins the transmit/receive acceptance filtering.
2.3
Programming the MultiCAN module
This section explains how to program the MultiCAN module for some typical use cases.
The following software tasks are processed in the CAN application:

Configuration of CAN node.

Allocate message objects via list commands.

Initialization of associated message objects.

Controlling a message transfer.

CAN error monitoring and restarting the CAN module.
2.3.1
Software initialization of MultiCAN
The initialization routine should process the following tasks:

Enable clock for MultiCAN module (see Figure 8)
− Release the MultiCAN clock gating via clear register bit CGATCLR1. MCAN0 (not in XMC4500).
− Release the MultiCAN peripheral via clear register bit PRCLR1.MCAN0RS.
− Switch clock fCLC on via clear register bit CAN_CLC.DISR and wait until flag CAN_CLC.DISS =0, which
indicates the MultiCAN has been enabled.
− Configure the module clock fCAN via register FDR for the bit timing configuration.
Note:
1. Two modes, normal divider mode and fractional divider mode, can be used via CAN_FDRx.DM. In general
the fractional divider mode provides the average output clock frequency with a simulated higher accuracy
than the normal divider mode, but fFD can have a maximum period jitter of one fPERIPH period. It is
NOTadvised to use the fractional divider mode. If the fractional divider is used, one fPERIPH cycle has to be
added to the jitter calculation.
Application Note
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V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
2. After the clock has been switched on, the CAN RAM is automatically initialized. The end of this CAN RAM
initialization is indicated by bit PANCTR.BUSY becoming in-active. Due to synchronisation effects, it is
advised to read back the previous register write (FDR), so that the BUSY bit is polled, when it is already set
the first time.

Configuration of CAN nodes.
− Set bit CAN_NCRx.CCE and INIT to active configuration mode of the CAN node without participation in
the CAN traffic. Configuration Mode is activated when bit NCRx.CCE is set to 1 (see page 8).
− Write CAN_NBTR for CAN baud rate configuration.
− Select CAN input pin or loopback mode via CAN_NPCRx.
− Interrupts and special node frame nodes can be optionally initialized via CAN_NIPRx and CAN_NFCRx.

Initialization of message objects.
− Allocate message objects to the corresponding CAN node via register CAN_PANCTR.
− Define and configure message objects for different tasks via register MOCTRn (DIR=’1’ or ‘0’).
− Program message objects identifier (MOARn) and acceptance mask for filtering (MOAMRn).
− Initialize data length code (MOFCRn.DLC) and data value TX message object.
− Enable interrupt for message object transmission and reception via register MOFCRn.

Initialize interfaces of MultiCAN, such as port pins for alternate function and interrupts, using CMSIS
functions.

Set CCE to 1 to protect against un-intended modification. Reset bit INIT to enable the participation of the
CAN node in the CAN traffic.
2.3.2
Software handling on CAN node
The software can use the bit TXOK/RXOK and all errors flags for evaluation of the node status.
In MultiCAN each node is equipped with a frame counter with the following selectable modes:

Frame count mode
− The default setting is that frame counter NFCRx.CFC is incremented upon reception/transmission of
defined frames (depending of NFCRx.CFSEL).

Bit timing mode
− CFC is used for analysis of the bit timing. Together with the CAN analyzer this feature is used for
baudrate detection. Example code is provided (see Example_6: Baudrate ).
Table 5
Frame counter modes
Mode
Flag NFCRx.CFCOV Function selection
(NFCRx.CFMOD) generated by
NFCR.CFSEL
Interrupt SRx
Frame count value
NFCRx.CFC
00B: frame count Transition from
mode
0xFFFF to 0x0000
Selectable:
xx1B/x1xB/1xxB
Selectable:
SR0…SR7
Frame count value
01B: Time stamp
mode
Transition from
0xFFFF to 0x0000
Only 000B
Selectable:
SR0…SR7
Captured bit time
count value
10B: Bit time
mode
update event of
CFC
Selectable xxxB, e.g.
000B: baudrate
detection
Fixed on SRx,
where x is the CAN
node number
fCLC clock cycles
Application Note
18
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family

Time-stamp mode
− CFC is used to count bit times. The frame counter is continuously incremented (internally) with the
beginning of a new bit time. Its value is permanently sampled in the NFCRx.CFC field while the bus is
idle. The value sampled just before the SOF bit of a new frame is detected is written to the
corresponding message object. When the treatment of a message object is finished, the sampling
continues.
2.3.3
Software control of a message transfer
Table 2 lists the maximum number of m essage objects in XMC4000 derivatives and the message objects
which can be set up for transmit or receive operation according to the selected value for control bit DIR.

TX message object (DIR=1); Set for data frames’ transmission and for remote frames’ reception.

RX message object (DIR=0); Set for data frames’ reception and for remote frames’ transmission.
Note: To enable CAN (data or remote) frame reception, bit RXEN must be set. For example, if RXEN=’0’ in a TX
message object (DIR=’1’) then a remote frame from CAN bus can not be restored in this object.
Software handling of a transmit message objct
Figure 10 demonstrates the software handling of a transmit (TX) message object (DIR=’1’).
If automatic handling is requested, bit TXEN0 must be initialized with ‘1’.
Together with TXEN1=1, the data transmission is started when flag TXRQ has been set by the hardware
because a received remote frame has a matching identifier.
Software handling of a receive message object
Figure 11 demonstrates the software handling of a receive (RX) message object (DIR=’0’).
RXEN must be set in a RX message object to enable receive data frame.
The reception of a data frame by hardware is indicated by NEWDAT=’1’ and RXPND=’1’.
Software processing of a received data frame should start by clearing NEWDAT and RXPND, after scanning
MSGLST. In an overwrite situation, the received information should be copied to an application data buffer
in order to release the message object for a new data frame.
Finally, NEWDAT and RXUPD should be checked again to ensure that the processing was based on a
consistent set of data and not on a part of the new message.
The software initialization or re-configuration of the message object properties always starts with disabling
via MSGVAL=’reset’. After re-configuration to activate the message object, bit MSGVAL must be reset using
RTSEL.
Bits TXEN0 and TXEN1 are software control bits used for different tasks:

Bit TEXN0 is defined for software control of the CAN frame trigger. For example:
− If a remote frame has been received in a TX message object, the send request TXRQ is set by hardware
automatically. When TXEN0=0 the transmission of a data frame from this TX message object is
suspended until it is re-enabled by software by setting TXEN0.
− In gateway structure, TXRQ is set in the destination object by hardware automatically when bit GDFS =
‘1’ in the source object is initialized.

Bit TXEN1 is defined to select the active TX message object in TxFIFO structure. TXEN1 with value ‘1’
moves along the TxFIFO structure as a token by hardware automatically.
Application Note
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V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
Clock/peripharal enabled
CAN node initialization
Allocate message objects
message object configuration in initialization phase
/re-configuration during CAN operation
Clear MSGVAL
DIR = ‚1':
Identifier AR:= application specific
Mask AM/MIDE: (for remote frame reception)
TXIE/RXIE:= application specific
Priority PRI:= 1 (recommended)
TXEN0/TXEN1:= application specific
RXEN:= 1 (for remote frame reception)
DLC:= application specific
Data:= application specific
NEWDAT:= 1
Clear RTSEL and set MSGVAL
Remote frame
received
Send data frame ?
Tx message object
updated by HW
(TXRQ is set by HW)
TXRQ is set ?
Trigger send request
no
TXEN0 & TXEN1= 1?
Set TXRQ, TXEN0, TXEN1
yes
Send data frame triggered
automatically by HW
yes
Update message ?
Figure 10
Software handling of a TX message object (DIR=’1’)
Application Note
20
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
Clock/peripharal enabled
CAN node initialization
Allocate message objects
message object configuration/re-configuration
Clear MSGVAL
DIR= ‚0':
Identifier AR:= application specific
Mask AMR/MIDE:= application specific
TXIE/RXIE:= application specific
Priority PRI:= 1 (recommended)
TXEN0/TXEN1:= application specific
RXEN:= 1
DLC:= dont‘ care
Data:= dont‘ care
Clear RTSEL and set MSGVAL
Data frame received
Want to send
Remote frame ?
Rx message object
updated by HW
(TXRQ is set by HW)
Trigger send request
Data frame received ?
(RXPND=‘1‘ or
NEWDAT=‘1‘)
Set TXRQ, TXEN0, TXEN1
yes
yes
Update message ?
SW handling
Clear NEWDAT and RXPND
Process message contents:
If (MSGLST)
; overwritten
else
; copy to SW buffer
...
If (NEWDAT==0 and RXUPD=0)
; ok
else
; an inconsistent info
Figure 11
Software handling of a RX message object (DIR=’0’)
Application Note
21
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
2.4
MultiCAN special features
2.4.1
Loop-back mode
Loop-back mode is used for internal testing.
In this mode the software driver can be developed and tested without being connected to a CAN bus system,
or safety tests can be run without being visible to the outside.
2.4.2
CAN analyzer mode
This mode is used for baudrate detection (see Example_6: Baudrate ). The hardware setting and software
initialization are the same as in a normal CAN system.
Bit CAN_NCRx.CALM must be set to active the analyzer mode.
In analyzer mode, data and remote frames are monitored without an active participation in any CAN transfer
(the CAN transmit pin is held on recessive level).
In this mode the data and remote frame can still be received and stored in the corresponding message
object, and interrupts are also generated, when this CAN frame is acknowledged by at least one other CAN
node.
2.4.3
MultiCAN FIFO
MultiCAN FIFO is based on the list structure; i.e. FIFO size is up to the maximum available message objects
(64 message objects in XMC4500 device).
As with the standard TX/RX message object, all FIFO elements must be assigned to the CAN node via panel
commands first. After assignment all FIFO objects are chained together in a list structure; each element has
its previous (PPREV) and next (PNEXT) message object.
A FIFO structure can have only one base object and several slave objects. The base object defines the FIFO
size with the point TOP and BOT, and additionally the CUR points to the active object for the next process.
Software programming for TxFIFO structure
In the TxFIFO structure the base and slave objects can be initialized with different IDs (including mask
register) and data contents. Each element is active for qualification in transmit acceptance filtering.
The right-hand side of Figure 12 shows the FIFO structure in one common list and the initialization of
TxFIFO message objects:

Allocate FIFO elements in a common list.

Configure TxFIFO base object and TxFIFO slave objects.

Set in all message objects excepted the CUR pointed object:
− TXEN1=0

Set in all message objects:
− TXRQ=0 if an automatically transmit process through TxFIFO via only one trigger request in the base
object is requested.
After the initialization routine, test software sets TXRQ in CUR pointed object.
The data frame information stored in this object will be sent on the CAN bus via token TXEN1, through all
TxFIFO elements.
In this example CUR moves MO8 àMO9 à MO10 à MO11 à MO8…
Application Note
22
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
Additionally, by initialization with the point SEL= MO8 in the base object, the FIFO overflow interrupt is
generated if CUR becomes equals to SEL; i.e. MO8…MO11 have finished their data frame transmission.
Note: For the TxFIFO structure the FIFO overflow interrupt is shared with the receive interrupt. In the example
above it triggers the MO8 receive interrupt.
CAN bus x
CAN bus x
data frames from CAN bus
data frames from MO8...MO11
CAN node x
MO8
CAN node x
RxFIFO base
.DIR=0
.MMC=1
.ID, IDs mask, MIDE
.BOT=MO8, TOP=MO11, CUR=MO8
.RXEN=1
MO8
TxFIFO base
.DIR=1
.MMC=2
.ID, DLC, data...
.BOT=MO8, TOP=MO11, CUR=MO8
.TXEN1=1
MO9
TxFIFO slave
.DIR=1
.MMC=3
.ID, DLC, data...
.CUR=MO8
.TXEN1=0
RxFIFO slave
.MMC=0
double-chained list MO9
.CUR don’t care
.RXEN=0
RxFIFO slave
.MMC=0
TxFIFO slave
.DIR=1
.MMC=3
double-chained list MO10 .ID, DLC, data...
.CUR=MO8
.TXEN1=0
MO10
.CUR don’t care
.RXEN=0
RxFIFO slave
.MMC=0
TxFIFO slave
.DIR=1
.MMC=3
MO11
.ID, DLC, data...
.CUR=MO8
.TXEN1=0
MO11
.CUR don’t care
.RXEN=0
XMC4000
XMC4000
RxFIFO
Figure 12
TxFIFO
MultiCAN FIFO in one common list
Software programming for RxFIFO structure
In the RxFIFO structure:

the base object is specified with MMC=0001B

the message object with MMC = 0000B is implicitly assumed for the slave object; i.e. slave objects perform
a standard RX message object delivery. This property cretes an RxFIFO structure to store CAN frames
with different IDs.
Note: In order to avoid direct reception of a message by a slave message object, as if it was an independent
message object and not a part of a FIFO, the bit RXEN of each slave object must be cleared. In this case
only the base object is active to qualify in receive acceptance filtering.
Application Note
23
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
The left-hand side of Figure 12 shows the FIFO structure in one common list and initialization of RxFIFO
message objects:

Allocate FIFO elements in a common list.

Configure the RxFIFO base object and the RxFIFO slave object.
Note: TXEN0 and TXEN1 have to be considered only when RxFIFO is used for transmitting remote frames.
In this example all received data frames with a matching identifier specified in MO8 (via MOARn and MOAMR)
are stored in the RxFIFO buffer.
The CUR moves MO8 àMO9 à MO10 à MO11 à MO8…
Additionally, by initialization with the point SEL= MO8 in the base object, the RxFIFO interrupt is generated if
CUR becomes equal to SEL; i.e. MO8…MO11 has been filled.
Note: For the RxFIFO structure the FIFO overflow interrupt is shared with the transmit interrupt. In the
example above, it triggers the MO8 transmit interrupt.
2.4.4
MultiCAN Gateway
The Gateway feature allows an automatic CAN frame re-routing between two independent CAN busses
without CPU interaction.
The Gateway in MultiCAN operates on the message object level; i.e. CAN frame information can be modified
including its identifier, baud rate, and data information for example, during transfer between two CAN bus
systems.
As with the FIFO, the Gateway structure in MultiCAN is realized by the list structure. A message object in the
Gateway structure is named ‘Gateway Source Object’ and ‘Gateway Destination Object’.
The ‘Gateway Source Object’ behaves as a standard message object with the following additional, selectable
actions:
Table 6
MultiCAN gateway feature (configured by the Gateway Source Object)
Source object
Destination object
MOFCRsource.IDC = ‘1’
MOARdestination updated with MOARsource
MOFCRsource.DLCC = ‘1’
MOFCRdestination.DLC updated with MOFCRsource.DLC
MOFCRsource.DATC = ‘1’
MODATAH/Ldestination copied from MODATAH/Lsource
MOFCRsource.GDFS = ‘1’
TXRQ is set in the ‘destination object’
Note: the actual destination object is activated by CUR point of the Source Object.
Use case 1:
Gateway Source Object: DIR=‘0’ and Gateway DestinationObject: DIR=‘1’
Data frame reception on Source Object side and transfer through Gateway to Destination side
Figure 13 shows Gateway use case for data frame reception.
Use case 2:
Gateway Source Object: DIR=‘1’ and Gateway Destination Object: DIR=‘0’
Remote frame reception on Source Object side and transfer through Gateway to Destination side
Application Note
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V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
Note: In the Gateway structure the ‘Gateway Source Object’ and ‘Gateway Destination Object’ must be
assigned to two different CAN nodes.
MMC=0100B specifies the ‘Gateway Source Object’.
As with the base object in FIFO structure, the ‘Gateway Source Object’ configures the Gateway Destination
structure via TOP, BOT, and CUR. The Gateway Destination structure may contain a single message object or
a FIFO structure.
Initialization of Gateway message objects

Allocate the Gateway Source Object and the Gateway Destination Objects in separate lists.

Configure Gateway Source Object (DIR=’0’) and parameters (IDC, DLCC, DATC, GDFS).

Configure Gateway Destionation Objects (DIR=’1’).
− Single Gateway Destination Object with MOFCRn.MMC = ‘0000B’.
− Gateway Destination Objects in TxFIFO (TxFIFO base object + TxFIFO slave objects).
Note:
1. Clear RXEN bit in the Gateway Destionation Objects in order to avoid direct remote frame receive.
2. Clear NEWDAT and TXRQ in the Gateway Destination Objects in order to avoid conflict with trigger signal
from the Gateway Source Object.
Application Note
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V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
MultiCAN in the XMC4000 family
CAN bus A
Data frame
CAN node y
CAN node x
Rx data (DIR=0)
.MMC=4 (gateway source)
.ID, mask, MIDE…
.IDC: application specific
MO10 .DATC: application specific
.DLCC: application specific
.GDFS: application specific
.CUR=BOT=TOP=MO20
.RXEN=1
Tx data (DIR=1)
.MMC=0 (Standard)
.ID, DLC, data...
MO20
.CUR don’t care
.TXEN0, TXEN1: application specific
XMC40000
Data frame
CAN bus B
Example_4: single gateway destination object
CAN bus A
Data frame
CAN node x
CAN node y
TxFIFO base (DIR=1)
.MMC=2
.ID, DLC, data...
MO20 .CUR=MO20
.BOT=MO20,TOP=MO21
.TXEN1=1
.TXEN0: application specific
Rx data (DIR=0)
.MMC=4 (source)
.ID, mask, MIDE…
.IDC: application specific
.DATC: application specific
MO10
.DLCC: application specific
.GDFS: application specific
.CUR=MO20
.BOT=MO20, .TOP=MO21
.RXEN=1
TxFIFO slave (DIR=1)
.MMC=3
.ID, DLC, data…
MO21
.CUR=MO20
.TXEN1=0
.TXEN0: application specific
XMC4000
Data frame
CAN bus B
Example_5: gateway destination in FIFO structure
Figure 13
MultiCAN Gateway
Application Note
26
V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
Implementing the example
3
Implementing the example
All example code supplied with this document can be integrated directly in compiler tools and run on all
XMC4000 Kits listed in Table 8.
Infineon provides freeware tool DAVE™, which integrates code generation, flash programming and
debugging.
3.1
First steps

Create a new “empty project” in the DAVE™ tool

Copy the example *.h and *.c files into the project directory.

Select macro definition in main.h for one of XMC4200, XMC4400, XMC4500 kit.
3.2

Example_1: Standard Message Object Transmission and Receive
Initialization:
− CAN_node0: MO8: TX message object (RXEN=1: receive remote frame).
− CAN_node1: MO16: RX message object.

Test_1: set trigger TXRQ (with TXEN0=1 and TXEN1=1) in MO8 to send data frame.

Test_2: set trigger TXRQ (with TXEN0=1 and TXEN1=1) in MO16 to send remote frame.
3.3

Example_2: Using Receive FIFO
Initialization:
− CAN_node0: MO16…MO19 RxFIFO structure within MO16 = RxFIFO base object for store data frame.
− CAN_node1: MO8: TX message object.

Test: load transmission data in MO8 and trigger send request afterwards for several times, and check the
received data in RxFIFO message objects.
3.4

Example_3: Using Transmit FIFO
Initialization:
− CAN_node0: MO8…MO11 TxFIFO within MO8 = TxFIFO base object. Each object has different 11bit_IDs,
DLC and data information, and prepared as before.
− CAN_node1: MO16…MO19 RxFIFO structure within MO16=RxFIFO base object.

Test: in this test TXRQ is set in MO9…MO11 during initialization routine so that all four data frames from
TxFIFO are transmitted by single trigger request in MO8 automatically.
3.5
Example_4: Using Gateway without FIFO
Data frame with 11bit_ID=0x444 are received on CAN_node2 and transmitted on CAN_node1 with
modification of ID=0x777 via the Gateway feature.

Initialization:
− CAN_node0: MO10: Gateway Source Object with ID=0x444 and DATC=1, DLCC=1, IDC=0, GDFS=1(copy
data bytes including DLC and set TXRQ).
Application Note
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V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
Implementing the example
− CAN_node1: MO20: Gateway Destination Object with 11bit_ID=0x777 (TXEN0=1, TXEN1=1 for
automatical trigger if data frame forwarded from source side).
− CAN_node2: test object MO50 (DIR=1, ID=0x444) and MO51 (DIR=0, ID=0x777).

Test: data frames with 11bit_ID=0x444 are created for MO10 on the bus (connected on CAN_node2). It
will be forwarded to MO20 (Gateway Destination side) and transmitted on CAN_node1 automatically
without any software control.
Note:
1. CAN_node2 with MO50, MO51 is defined here for a simple test of the Gateway function in loop-back mode,
because on the XMC4000 kit only the CAN_TX/_RX pin of CAN_node2 are available.
2. Because this example code uses loop-back mode, all RX message objects have dedicated IDs (with
acceptance mask on) in order to avoid endless transmit due to unintended message object storage.
3.6
Example_5: Using Gateway with FIFO
Data frames with 11bit_ID=0x444 are received on CAN_node2 and transmitted on CAN_node1 with
modification of ID=0x777 via the Gateway feature.

Initialization:
− CAN_node0: MO10 Gateway Source Object with ID=0x444 and DATC=1, DLCC=1, IDC=0, GDFS=0 (copy
data bytes including DLC, but do not set TXRQ).
− CAN_node1: MO20/MO21 Gateway Destination Objects in FIFO structure with ID=0x777 (TXEN0=0 in
MO2/MO21: Sending on Destination side is controlled by software).
− CAN_node2: test objects MO50 (DIR=1, ID=0x444) and MO51 (DIR=0, ID=0x777).

Test: data frames with 11bit_ID=0x444 are created for MO10 on the bus (connected on CAN_node2).
Software checks information in MO20/MO21 (Gateway Destination side). At the end the data frame in
MO20/MO21 is sent out on bus (connected on CAN_node1) and via set TXEN0 in MO20/MO21.
3.7
Example_6: Baudrate detection
In some applications it is necessary to detect the baudrate without any influence on the bus. The MultiCAN
analyzer can be used to monitor bus transfer without any activity on the bus itself.
The main point for baudrate detection is to detect the minimal time (one bit ‘0’ and one bit ‘1’) of a whole
CAN frame, therefore here it requires a specific ID or data field (byte 0x55) from the active CAN node.
The bit timing frame mode is implemented in MultiCAN. In setting NCRn.CFMOD=10B with
NFCRn.CFCSEL=000B, the clock cycles of fCAN counts up at the dominant edge monitored on the CAN receive
input line, and is then stored in the NFCRn.CFC.
‚0'
‚1'
‚0'
‚0'
‚1'
‚0'
counts up and cycles of fCAN is stored into NFCRn.CFC
Figure 14
Baudrate detection
Application Note
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V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
Implementing the example
In this example the minimum duration is calculated after 200 samples. The recorded minimum value is used
for the baudrate calculation.
One CAN bit must be from 8 to maximum 25 time quanta. In test software typical values for the bit timing
setting (register BTR.TSEG1, TSEG2 for 8…25 tq) are pre-defined and used for searching a suitable BTR
parameter.
Due to PLL jitter in this test, the MultiCAN clock links directly to the external oscillator clock (fosc=12MHz).
The following table shows register BTR settings inside MultiCAN module when baudrate has been detected
in test.
Table 7
The BTR value in XMC by testing
CAN frame with baudrate from host CAN (e.g. CANalyzer)
BTR value( with fCAN=fOSC = 12MHz)
1000K
0x27C0
500K
0x6FC0
250K
0x6FC1
125K
0x6FC3
100K
0x6FC4
Application Note
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V1.0, 2015-07
Controller Area Network Controller (MultiCAN)
AP32300
Running example code
4
Running example code
To run the Example_6: Baudrate , an XMC4x00 CPU kit and COM_ETH are required. See Table 8 for the
different CAN pins on XMC4x00 CPU kits.
Other examples use loop-back mode, and only one XMC4x00 CPU kit is required.
Running in loop-back mode:

XMC4x00 CPU kit in the normal boot mode (switch: BSL=OFF, CAN/UART=does not matter).

Connect the on-board USB connector (for power supply and debug tool) to the PC USB port.

Start the DAVE™ tool, start the compiler, download the code and run it.
Running Example_6: Baudrate

All hardware should be connected as in Figure 15.

XMC4x00 CPU kit in the normal boot mode (switch: BSL=OFF, CAN/UART=does not matter).

Connect the on-board USB connector (for power supply and debug tool) to the PC USB port.

Connect CAN cable CANH/CANL between host device (the CANalyzer tool for example) and XMC4x00
board:
In CANalyzer tool (host device):

Set the baud rate and active setting ACK.

Insert a generator block and create one data frame (recommended: ID=0x555, bytes=0x55).
After all of the steps above have been successfully completed, the tool can be started:

Start the DAVE tool, start the compiler, download the code and run it.

Start the CANalyzer and trigger a data frame.
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AP32300
Running example code
CANH/CANL
Setting in CANalyzer tool
On-board USB debugger
Figure 15
Running the baudrate detection example
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AP32300
DAVE™ and XMCLib
5
DAVE™ and XMCLib
All example code supplied with this document is also created in DAVE™4 by using XMCLib. In the source code
you can find information about using the MultiCAN XMCLib.
5.1
Implementation with XMCLib
This section will provide a guide to set up a basic project for CAN communication using the Infineon XMCLib.
Definition and configuration:
Global CAN frequency definition:
#define CAN_FREQUENCY_120 120000000

CAN bit timing configuration:
XMC_CAN_NODE_NOMINAL_BIT_TIME_CONFIG_t CanBaud_cfg=
{
.can_frequency = CAN_FREQUENCY_120, // fCAN=120MHz
.baudrate = (1000 * 1000),
// baudrate=1000K
.sample_point = (80 * 100),
// Sample point=80%
.sjw = 2
// SJW=1+1
};

User CAN message object definition:
XMC_CAN_MO_t userSW1_MO8_Tx = {
.can_mo_type
= XMC_CAN_MO_TYPE_TRANSMSGOBJ,
.can_id_mode
= XMC_CAN_FRAME_TYPE_STANDARD_11BITS,
.can_priority
= XMC_CAN_ARBITRATION_MODE_ORDER_BASED_PRIO_1,
.can_identifier
= (uint32_t)0x111,
.can_id_mask
= (uint32_t)0x7ff,
.can_ide_mask
= 1U,
.can_mo_ptr
= (CAN_MO_TypeDef*)CAN_MO8,
.can_data_length = (uint8_t)8,
.can_data[1]
= 0x88888888,
.can_data[0]
= 0x88888888
};

Initialization:
Global initialization:
// release MultiCAN module via PRSTAT1,
// Configuration of CAN clock:
// registers: CAN->CLC and CAN->FDR, fcan=120Mhz
XMC_CAN_Init((CAN_GLOBAL_TypeDef*)CAN, CAN_FREQUENCY_120);

CAN node initialization:
// CAN node configuration and message object configuration

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DAVE™ and XMCLib
XMC_CAN_NODE_NominalBitTimeConfigure(CAN_NODE2, &CanBaud_cfg);
XMC_CAN_NODE_EnableConfigurationChange(CAN_NODE2);
XMC_CAN_NODE_EnableLoopBack(CAN_NODE2);
XMC_CAN_NODE_DisableConfigurationChange(CAN_NODE2);
Initialization Message object initialization
// Configuration of the CAN Message Object List Structure:
XMC_CAN_AllocateMOtoNodeList((CAN_GLOBAL_TypeDef*)CAN, 2, 8);

// Configuration of the CAN Message Objects:
XMC_CAN_MO_Config(&userSW1_MO8_Tx);
Disable configuration mode and enable CAN node
//
Start the CAN Nodes:
XMC_CAN_NODE_DisableConfigurationChange (CAN_NODE2);
XMC_CAN_NODE_ResetInitBit(CAN_NODE2);

Definition and configuration Function implementation:
Data frame transmission: following code is usually called for data frame transmission
// test value
uint8_t TestSW1_TxData[8]={0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77}

// load DLC and TxData bytes
userSW1_MO8.can_data_length = 8;
for(i=0; i<8; i++)
userSW1_ MO8.can_data_byte[i] =TestSW1_TxData[i];
XMC_CAN_MO_UpdateData(&userSW1_MO8);
// set trigger
XMC_CAN_MO_Transmit(&userSW1_MO8);
Data frame reception
// update all information defined in user CAN message object SW_MO
XMC_CAN_MO_Receive(&userSW1_MO16_Rx);
// update only data bytes in user CAN message object SW_MO
XMC_CAN_MO_ReceiveData(&userSW1_MO16_Rx);

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Appendix
6
Appendix
6.1
Kit information
Infineon provides several XMC4000 Application kits.The CAN interfaces use different pins (hard-wired) on
different board versions.
Table 8
XMC4000 Application Kit signal connections
Host board kits
CAN node (in the normal boot mode)
LED
CPU_45A_V3
(XMC4500_AC)
CAN connector is not available on CPU_45A_V3.
CAN pins must be connected via COM pin connector.
CAN2_TxD=P1.9 => Pin28.
CAN2_RxD=P1.8 => Pin30.
P3.9
CPU_44A_V2
(XMC4400_AB)
CAN connector is not available on CPU_44A_V2.
CAN pins must be connected via COM pin connector.
CAN1_TxD=P1.12 => Pin28.
CAN1_RxD=P1.4 =>Pin30.
P1.8
COM pin
connector
Pin connector between CPU kit and COM_ETH kit.
COM_ETH_V1
CAN transceiver with CAN connector (DE-9).
CAN signal:
Pin28=CAN_TXD.
Pin30=CAN_RXD.
CPU_42A_V1
(XMC4200_AA)
CAN connector is available on CPU_42A_V1: CAN
transceiver with CAN connector (DE-9).
CAN1_TxD=P1.5.
CAN1_RxD=P1.4.
P2.1
Note: On all XMC CPU kits an external 12 MHz crystal provides the clock signal to the XMC microcontroller.
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AP32300
Revision History
7
Revision History
Major changes since the last revision
Page or Reference
Description of change
V1.0
Initial Version
Application Note
35
V1.0, 2015-07
Trademarks of Infineon Technologies AG
AURIX™, C166™, CanPAK™, CIPOS™, CIPURSE™, CoolGaN™, CoolMOS™, CoolSET™, CoolSiC™, CORECONTROL™, CROSSAVE™, DAVE™, DI-POL™, DrBLADE™,
EasyPIM™, EconoBRIDGE™, EconoDUAL™, EconoPACK™, EconoPIM™, EiceDRIVER™, eupec™, FCOS™, HITFET™, HybridPACK™, ISOFACE™, IsoPACK™, iWafer™, MIPAQ™, ModSTACK™, my-d™, NovalithIC™, OmniTune™, OPTIGA™, OptiMOS™, ORIGA™, POWERCODE™, PRIMARION™, PrimePACK™,
PrimeSTACK™, PROFET™, PRO-SIL™, RASIC™, REAL3™, ReverSave™, SatRIC™, SIEGET™, SIPMOS™, SmartLEWIS™, SOLID FLASH™, SPOC™, TEMPFET™,
thinQ!™, TRENCHSTOP™, TriCore™.
Other Trademarks
Advance Design System™ (ADS) of Agilent Technologies, AMBA™, ARM™, MULTI-ICE™, KEIL™, PRIMECELL™, REALVIEW™, THUMB™, µVision™ of ARM
Limited, UK. ANSI™ of American National Standards Institute. AUTOSAR™ of AUTOSAR development partnership. Bluetooth™ of Bluetooth SIG Inc. CATiq™ of DECT Forum. COLOSSUS™, FirstGPS™ of Trimble Navigation Ltd. EMV™ of EMVCo, LLC (Visa Holdings Inc.). EPCOS™ of Epcos AG. FLEXGO™ of
Microsoft Corporation. HYPERTERMINAL™ of Hilgraeve Incorporated. MCS™ of Intel Corp. IEC™ of Commission Electrotechnique Internationale. IrDA™ of
Infrared Data Association Corporation. ISO™ of INTERNATIONAL ORGANIZATION FOR STANDARDIZATION. MATLAB™ of MathWorks, Inc. MAXIM™ of Maxim
Integrated Products, Inc. MICROTEC™, NUCLEUS™ of Mentor Graphics Corporation. MIPI™ of MIPI Alliance, Inc. MIPS™ of MIPS Technologies, Inc., USA.
muRata™ of MURATA MANUFACTURING CO., MICROWAVE OFFICE™ (MWO) of Applied Wave Research Inc., OmniVision™ of OmniVision Technologies, Inc.
Openwave™ of Openwave Systems Inc. RED HAT™ of Red Hat, Inc. RFMD™ of RF Micro Devices, Inc. SIRIUS™ of Sirius Satellite Radio Inc. SOLARIS™ of Sun
Microsystems, Inc. SPANSION™ of Spansion LLC Ltd. Symbian™ of Symbian Software Limited. TAIYO YUDEN™ of Taiyo Yuden Co. TEAKLITE™ of CEVA, Inc.
TEKTRONIX™ of Tektronix Inc. TOKO™ of TOKO KABUSHIKI KAISHA TA. UNIX™ of X/Open Company Limited. VERILOG™, PALLADIUM™ of Cadence Design
Systems, Inc. VLYNQ™ of Texas Instruments Incorporated. VXWORKS™, WIND RIVER™ of WIND RIVER SYSTEMS, INC. ZETEX™ of Diodes Zetex Limited.
Last Trademarks Update 2014-07-17
www.infineon.com
Edition 2015-07
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2015 Infineon Technologies AG.
All Rights Reserved.
Do you have a question about any
aspect of this document?
Email: [email protected]
Document reference
AP32300
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