CAN Networking
Technical Principle
• Wake up behavior according ISO 11898-5
• All ECUs are woken-up by any activity on the bus (global wake-up)
ECU 2 ECU 3 ECU 4 ECU 5
ECU X ECU active
Typical applications:
• Door Modules
• Sun Roof Module
• Windowlifter
• Seat Modules
• Park Assistance
• Trailer Interface
• Park-Heating system
• Trunk Module ECU 1
Partial Networking
Generic Idea of “Partial Networking”
Without Partial Networking: With Partial Networking:
PN-enabled networks are capable of operating only those parts of a network that are functionally required at a given time
Partial Networking
Technical Principle
Wake up behavior according ISO 11898-6
Partial Networking is the ability to operate certain parts of a network while others remain inactive
Normal Bus traffic does not wake up a partial network enabled ECU
ECU 2 ECU 3 ECU 4 ECU 5
ECU in sleep mode
Typical applications:
• Door Modules
• Sun Roof Module
• Windowlifter
• Seat Modules
• Park Assistance
• Trailer Interface
• Park-Heating system ECU 1
Partial Networking
CAN protocol decoder
RXD Oscillator
Wake-up frame configuration
memory
14V SCSN SCLK SDI SDO
INH
SPI
5V
Message filter
&
+/- 1% Accuracy
Product differentiator
Standby Mode Sleep Mode
Partial Networking – Wake Up
Identifier
• Wake Up Message defined by Identifier and DLC
• Identifier:
−Use of 11 bit or 29 bit Identifier
−Single identifier (all 11/29 bits are defined)
−Group of identifiers (min one bit don´t care)
relevant Irrelevant
Mask: Certain ID bits are irrelevant
Example: 11 bit Identifier
Mask: All ID bits are relevant
Example configuration 11bit ID
ID Range: 0x1A0 – 0x1A7 Binary: 001 1010 0xxx This configuration allows up to 8 different nodes
Partial Networking – Wake Up
Data Length Code
• Data Length Code (DLC)
−0 … 8: Defines the length of the wake message in Byte‘s
−Expected Data length and received data length have to be equivalent to identify a valid Wake message
Example configuration Data length: 1 Byte = 8 Bit
This configuration allows up to 8 different groups of nodes to be woken-up simultaneously with one wake-up message.
Partial Networking – Wake Up
Addressing Groups (Data Field)
• Addressing (Data Field)
−Is irrelevant if DLC=0
−Every single bit is used to address a dedicated group of CAN nodes (can adress only 1 or up to 64 groups in one message)
−Individual Nodes can be members of 1 or more groups
Example configuration Group 1: Node 1, Node 2 Group 2: Node 5
Group 3: Node 1, Node 7, … 1 Group = 1 Use Case !
Partial Networking – Wake Up
Wake-Up process/workflow
DLC
0 0 1 1 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 0 0 IdentifierDLC Datafield 0 0 1 1 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 0 0
Identifier Datafield
Configuration node 1: ID range: 0x1A0 – 0x1A7, DLC=1, Groups 1, 3 DLC
Configuration node 2: ID range: 0x1A0 – 0x1A7, DLC=1, Groups 1, 4
Received message:
Partial Networking – Wake Up
Wake-Up process/workflow
DLC
0 0 1 1 0 1 0 0 0 1 0 0 0 0 1 0 1 1 1 1 0 0 0
Identifier Datafield
Configuration node 1: ID range: 0x1A0 – 0x1A7, DLC=1, Groups 1, 3
1 2 3 4 5 6 7 8
Configuration node 2: ID range: 0x1A0 – 0x1A7, DLC=1, Groups 1, 4
Received message:
matchmatchmatchmatchmatchmatchmatchmatchdon’t caredon’t caredon’t carematchmatchmatchmatch End of ID and control field:
Complete match Valid wake-up message !
Partial Networking – Wake Up
Wake-Up process/workflow
DLC
0 0 1 1 0 1 0 0 0 1 0 0 0 0 1 0 1 1 1 1 0 0 0
Identifier Datafield
Configuration node 1: ID range: 0x1A0 – 0x1A7, DLC=1, Groups 1, 3
1 2 3 4 5 6 7 8
Configuration node 2: ID range: 0x1A0 – 0x1A7, DLC=1, Groups 1, 4
Received message:
No Wake-up!
No Wake-up!
Wake-up
Wake-up
Actually the wake-up happens only in case the CRC has been received correctly.
Group1: No wake-upGroup2: Wake-upGroup3: Wake-upGroup4: Wake-up
Challenges of Introducing CAN FD for General Operation
Core Problem: CAN FD and “Classic” CAN nodes cannot be simply mixed, while not all nodes need bandwidth acceleration Gateway
EPS Cl
TCU
ECU
Chassis ADAS Power Train
Gateway
EPS
Cl ECU
Chassis ADAS Power Train TCU CAN FD Fast Branch
Classic CAN Network
- Critical nodes at bandwidth limit (either flashing or general use) - Network organised by function
Option 1: CAN FD Fast Branch
- Networks organised by technology, not function.
- Increased routing via gateway - Complicated firewall policies - Lacks scalability
- Sub-optimal wiring solutions
Gateway
EPS Cl
TCU
ECU
Chassis ADAS Power Train
Option 2: Update complete branch
- Network organised by function - Legacy nodes updated
- Higher development costs
- Lack of MCU availability // Higher cost of MCU
CAN Flexible Data Impact on ISO11898-6 Physical Layer
Flexible Data passive
• CAN Flexible Data frame should not “disturb” Partial Networking transceiver:
• The circuitry must be designed to avoid “Error Detection” and to prevent the Frame Error Counter from increasing and falsely waking up the transceiver
• Proper detection of “End of frame / Idle detection”
Regular CAN Frame
Idle phase detection (11 recessive bits)
No idle phase detection during the Fast data
CAN FD Frame
FD frame detection(r0 bit)
=> stop decoding
SOFSOF ACK ACKFast data SOF SOF
CAN FD Passive: Enhancing Partial Networking
TJA1145 offers partial networking functionality according to ISO11898-6
– CAN FD frames will be seen as coding errors and thus TJA1145 will wake-up with error
counter overflow when in partial networking sleep mode
TJA1145FD offers additionally the option to remain in partial networking sleep mode, when CAN FD frames occur on the bus
– CAN FD frames are recognized by their recessive FDF bit and judged as ‘valid CAN frames’ regardless of what comes after the FDF bit
Partial Partial FD-active
FD-active FD-active Enh partial Enh partial FD-active
Wake-up due to CAN FD traffic CAN Error Frames No Wake-up due to CAN FD traffic
Partial Networking today FD-passive Partial Networking
CAN FD – bit Rates Above 1 MBps
Classic CAN operation (all nodes)
e.g. during standard operation mode
TJA
CAN FD operation(limited number of nodes) e.g. during Software download
or ‘high performance communication modes’
TJA
CAN FD -5MBit/s
CAN