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SLIDE 1

International CAN Conference 2015, Vienna Dr.–Ing. Marc Schreiner – Daimler AG

SLIDE 2

Overview:

Acquisition and assessment of CAN FD signals
Determination of a safe operation area for CAN FD topologies
Typical characteristics of CAN FD topologies:

− Point to point link − Line topology − Bus topology with stubs − Star topology

Marc Schreiner, International CAN Conference 2015, Vienna 2

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0,4

0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0 200 400 600 800 1000 1200 1400

75 75 78,5 75 75 76 80 80 75 75 78,5 75 75 76 80 80 60 60 57 56 60 60 60 60 60 60 57 56 60 60 60 60

phase margin (ns) Baudrate (Mbit/s) PM1 PM2 sample point (%)

Marc Schreiner, International CAN Conference 2015, Vienna 3

Theory: Definition of PM1 and PM2

Robustness of a CAN FD Bus System – About Oscillator Tolerance and Edge Deviations – A. Mutter, iCC 2013 Paris

Task: Design of a new CAN FD network

ECU1 T ECU5 4m 2,5m PC 7,5m 7m 0,3m ECU4 2m CAN 3m ECU7 ECU6 5m 5m 0,3m T ECU2 ECU3

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TX TX TX TX TX TX TX TX RX RX RX RX RX RX RX RX µC µC µC µC CAN_H CAN_H CAN_H CAN_H CAN_L CAN_L CAN_L CAN_L

CAN topology under test

CAN node 1 CAN node 1 CAN node n-1 CAN node n scope Tx1 (trigger) scope bus 1 scope bus 2 scope RX1 scope RX2

S E SE SE S E diff diff

trigger once at all nodes measure once at all nodes for all trigger positions result: matrix with n² measurements

Marc Schreiner, International CAN Conference 2015, Vienna 4

Node 1 Node 2 Node 3 Node 4 Node 5 Node 6 Node 6 Node 5 Node 4 Node 3 Node 2 Node 1

receiver transmitter receiver transmitter

Node 1 Node 2 Node 3 Node 4 Node 5 Node 6 Node 6 Node 5 Node 4 Node 3 Node 2 Node 1

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1 2 3 4 7 1 , 5 µ 7 1 , 7 5 µ 7 2 , µ 7 2 , 2 5 µ 7 2 , 5 µ 7 2 , 7 5 µ 7 3 , µ 7 3 , 2 5 µ 7 3 , 5 µ 7 3 , 7 5 µ

1

1 2 3 RX / TX signal (V)

logic transmitted TX logic received RX

500mV differential bus signal (V)

differential bus signal at receiver 0.5V/0.9V transceiver thresholds

900mV

t(s)

Marc Schreiner, International CAN Conference 2015, Vienna 5

RX TX CAN bus ringing! virtual RX signal based on bus signal bit size based on real RX signal

ringing!

ringing!

SLIDE 6

Marc Schreiner, International CAN Conference 2015, Vienna 6

40n 80n 120n 160n 2 nodes 3 nodes 4 nodes 5 nodes 6 nodes 7 nodes 8 nodes asymmetrty (s) loopback signal 20 40 60 80 100 120 40n 80n 120n 160n 200n communication between nodes asymmetry (s) total bus length (m) 2 nodes 3 nodes 4 nodes 5 nodes 6 nodes 7 nodes 8 nodes 40n 80n 120n 160n 2 nodes 3 nodes 4 nodes 5 nodes 6 nodes 7 nodes 8 nodes asymmetrty (s) loopback signal 20 40 60 80 100 120 40n 80n 120n 160n 200n communication between nodes asymmetry (s) total bus length (m) 2 nodes 3 nodes 4 nodes 5 nodes 6 nodes 7 nodes 8 nodes evaluation based on real RX signal evaluation based on virtual RX signal

PM1, PM2 PM1, PM2 PM1, PM2 PM1, PM2 safety margin safety margin safety margin safety margin safe topologies safe topologies safe topologies safe topologies

RX TX CAN bus

Node 1 Node 2 Node 3 Node 4 Node 5 Node 6 Node 6 Node 5 Node 4 Node 3 Node 2 Node 1

SLIDE 7

!

The graphs given in the following show the of a set of

topologies with varying parameters at room temperature.

The results include the topology and typical transceivers.
The mark the range that contains all measured asymmetry

values of all variations that have been tested. These experimental results do not claim to be exhaustive (e.g. temperature, tolerances etc.). ! " The plots cannot replace a CAN FD system designer’s duty to individually check a topology under development.

Marc Schreiner, International CAN Conference 2015, Vienna 7

SLIDE 8

""#$

evaluation based on virtual RX signal 50n 100n 150n 200n 250n 300n 350n both-sided term.

nesided term.

asymmetry (s) 20 40 60 80 100 120 40n 80n 120n 160n 200n both-sided term.

nesided term.

communication A→B loopback signal asymmetry (s) transmission line length (m)

communication stopped at 32m with test baudrate due to high loop back asymmetry

50n 100n 150n 200n 250n 300n 350n both-sided term.

nesided term.

asymmetry (s) 20 40 60 80 100 120 40n 80n 120n 160n 200n both-sided term.

nesided term.

communication A→B loopback signal asymmetry (s) transmission line length (m)

communication stopped at 32m with test baudrate due to high loop back asymmetry

e v a l u a t i

n

b a s e d

n

r e a l R X s i g n a l

Marc Schreiner, International CAN Conference 2015, Vienna 8

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#

Marc Schreiner, International CAN Conference 2015, Vienna 9

40n 80n 120n 160n 2 nodes 3 nodes 4 nodes 5 nodes 6 nodes 7 nodes 8 nodes 12 nodes 14 nodes asymmetrty (s) loopback signal 20 40 60 80 100 120 40n 80n 120n 160n 200n communication between nodes asymmetry (s) total bus length (m) 2 nodes 3 nodes 4 nodes 5 nodes 6 nodes 7 nodes 8 nodes 12 nodes 14 nodes 40n 80n 120n 160n asymmetry increasing with number of nodes 2 nodes 3 nodes 4 nodes 5 nodes 6 nodes 7 nodes 8 nodes 12 nodes 14 nodes 16 nodes asymmetrty (s) loopback signal 20 40 60 80 100 120 40n 80n 120n 160n 200n asymmetry increasing with bus length communication between nodes asymmetry (s) total bus length (m) 2 nodes 3 nodes 4 nodes 5 nodes 6 nodes 7 nodes 8 nodes 12 nodes 14 nodes 16 nodes asymmetry increasing with number of nodes evaluation based on real RX signal evaluation based on virtual RX signal

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%&#

100n 200n 300n 400n 500n 600n ls ≤ 0,25m ls ≤ 0,5m ls ≤ 1m ls ≤ 2m ls ≤ 2m ls ≤ 1m ls ≤ 0,5m ls ≤ 0,25m loopback signal 1 stub 2 stubs 3 stubs 4 stubs 5 stubs 6 stubs asymmetrty (s) 20 40 60 100n 200n 300n 400n 500n 600n communication between nodes asymmetry (s) main bus length (m) 1 stub 2 stubs 3 stubs 4 stubs 5 stubs 6 stubs 100n 200n 300n 400n 500n 600n

ls = 0,25 m

ls = 0,5 m ls = 1 m ls = 2 m ls = 4 m

asymmetry increasing with

number of stubs and stub length 1 stub 2 stubs 3 stubs 4 stubs 5 stubs 6 stubs asymmetrty (s) loopback signal

20

40 60 100n 200n 300n 400n 500n 600n asymmetry (s) main bus length (m) 1 stub 2 stubs 3 stubs 4 stubs 5 stubs 6 stubs communication between nodes ls = 0,25 m ls = 0,5 m ls = 1 m ls = 2 m ls = 4 m asymmetry increasing with number of stubs and stub length evaluation based on real RX signal evaluation based on virtual RX signal

Marc Schreiner, International CAN Conference 2015, Vienna 10

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%&&

100n 200n 300n 400n 500n 600n 700n

ffset stub length

lo = 1,25 m lo = 1,5 m lo = 2 m lo = 3 m lo = 5 m 1 sub / 1 offset stub 2 subs / 1 offset stub 3 subs / 1 offset stub ls = const. = 1m loopback signal asymmetrty (s)

20

40 100n 200n 300n 400n 500n 600n 700n

ffset stub length

lo = 1,25 m lo = 1,5 m lo = 2 m lo = 3 m lo = 5 m ls = const. = 1m asymmetry (s) main bus length (m) 1 sub / 1 offset stub 2 subs / 1 offset stub 3 subs / 1 offset stub communication between nodes 100n 200n 300n 400n 500n 600n 700n loopback signal 1 sub / 1 offset stub 2 subs / 1 offset stub 3 subs / 1 offset stub

asymmetrty (s)
ffset stub length

lo = 1,25 m lo = 1,5 m lo = 2 m lo = 3 m lo = 5 m

ther stubs:

ls = const. = 1m 20 40 100n 200n 300n 400n 500n 600n 700n

ffset stub length

lo = 1,25 m lo = 1,5 m lo = 2 m lo = 3 m lo = 5 m

ther stubs:

ls = const. = 1m communication between nodes asymmetry (s) main bus length (m) 1 sub / 1 offset stub 2 subs / 1 offset stub 3 subs / 1 offset stub evaluation based on real RX signal evaluation based on virtual RX signal

Marc Schreiner, International CAN Conference 2015, Vienna 11

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100n

200n 300n 400n 500n 600n 3 branches 4 branches 5 branches 6 branches 7 branches 8 branches 12 branches asymmetrty (s) loopback signal not analysable, ringing > tBit not analysable, ringing > tBit 2 4 6 8 100n 200n 300n 400n 500n communication between nodes asymmetry (s) branch length (m) 3 branches 4 branches 5 branches 6 branches 7 branches 8 branches 12 branches 100n 200n 300n 400n 500n 600n low loopback asymmetry 3 branches 4 branches 5 branches 6 branches 7 branches 8 branches 12 branches asymmetrty (s) loopback signal asymmetry increasing with number of branches 2 4 6 8 100n 200n 300n 400n 500n communication between nodes asymmetry (s) branch length (m) 3 branches 4 branches 5 branches 6 branches 7 branches 8 branches 12 branches evaluation based on real RX signal evaluation based on virtual RX signal

Marc Schreiner, International CAN Conference 2015, Vienna 12

SLIDE 13

'

A workflow for the assessment of CANFD topologies has been presented. The maximum asymmetry of various CAN FD topologies has been compared, based on the logic RX signal and on the signal quality on the bus lines. #$

most suitable for high communication speeds, very low ringing
lowest risks for signal integrity issues
tradeAoffs have to be made for higher communication speeds
ringing on the bus lines causes risks for signal integrity issues
if stubs are needed they should be as short as possible

%&

nly suitable for high communication speed if branches are very short

Marc Schreiner, International CAN Conference 2015, Vienna 13

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International CAN Conference 2015, Vienna Dr.–Ing. Marc Schreiner – Daimler AG

SLIDE 15

%$

Exemplary signal shapes
Safety margin

Marc Schreiner, International CAN Conference 2015, Vienna 15

SLIDE 16

()

Marc Schreiner, International CAN Conference 2015, Vienna 16

1 2 3 4 5 79,0µ 79,5µ 80,0µ 80,5µ 81,0µ

1

1 2 3

504n 507,2n 507,2n 492,8n 492,8n BYTE6 BIT BYTE6 BIT BYTE6 BIT BYTE6 BIT BYTE6 BIT

RX/TX (V)

TX ID: 201 RX Bit Length Dom FD Bit Length Rez FD Sample Points

diff. Bus (V)

t (s)

0.9V / 0.5V Bus TX Bus RX

1 2 3 4 5 79,0µ 79,5µ 80,0µ 80,5µ 81,0µ

1

1 2 3

531,2n 532,8n 534,4n 467,2n 467,2n BYTE6 BIT BYTE6 BIT BYTE6 BIT BYTE6 BIT

RX/TX (V)

TX ID: 200 RX Bit Length Dom FD Bit Length Rez FD Sample Points

diff. Bus (V)

t (s)

0.9V / 0.5V Bus TX Bus RX

point to point link with single sided termination point to point link with termination at both sides

SLIDE 17

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Marc Schreiner, International CAN Conference 2015, Vienna 17

1 2 3 4 5 74,0µ 74,5µ 75,0µ

1

1 2 3

540,8n 459,2n 459,2n BYTE6 BIT BYTE6 BIT BYTE6 BIT

RX/TX (V)

TX ID: 206 RX Bit Length Dom FD Bit Length Rez FD Sample Points

diff. Bus (V)

t (s)

0.9V / 0.5V Bus TX Bus RX

bus with stubs (measured at long stub line) line topology (measured at midAnode)

1 2 3 4 5 73,0µ 73,5µ 74,0µ 74,5µ 75,0µ

1

1 2 3

504n 502,4n 496n 497,6n 496n BYTE6 BIT BYTE6 BIT BYTE6 BIT BYTE6 BIT BYTE6 BIT

RX/TX (V)

TX ID: 202 RX Bit Length Dom FD Bit Length Rez FD Sample Points

diff. Bus (V)

t (s)

0.9V / 0.5V Bus TX Bus RX

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()

Marc Schreiner, International CAN Conference 2015, Vienna 18

1 2 3 4 5 73,0µ 73,5µ 74,0µ 74,5µ 75,0µ

1

1 2 3

643,2n 643,2n 355,2n 356,8n 356,8n BYTE6 BIT BYTE6 BIT BYTE6 BIT BYTE6 BIT BYTE6 BIT

RX/TX (V)

TX ID: 206 RX Bit Length Dom FD Bit Length Rez FD Sample Points

diff. Bus (V)

t (s)

0.9V / 0.5V Bus TX Bus RX

star topology (measured at long branch)

SLIDE 19

CAN FD from a view point of an OEM, Marc Schreiner A Daimler AG, 12. Nov. 2013, iCC 2013 Paris

19

topology delay and symmetry worst case transceiver characteristics clock tolerances jitter EMI jitter margin for future extensions

+ PLL

temperature effects

ther circuitry effects

aging ISO11898A2