��� ���������������� International CAN Conference 2015, Vienna Dr.–Ing. Marc Schreiner – Daimler AG
��� ���������������� 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 2 Marc Schreiner, International CAN Conference 2015, Vienna
���������� Theory: Definition of PM1 and PM2 Task: Design of a new CAN FD network 80 1400 1200 ECU2 ECU3 80 60 0,3m T 1000 2,5m 2m 3m 7,5m ECU1 4m 7m 76 60 800 phase margin (ns) 60 75 CAN 60 ECU4 PC sample point (%) 60 600 75 60 78,5 5m 5m 60 0,3m 75 80 400 56 60 75 T 57 60 56 80 57 60 76 ECU5 ECU6 ECU7 60 75 60 200 75 78,5 75 PM1 75 PM2 0 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0 Baudrate (Mbit/s) �������� Robustness of a CAN FD Bus System – About Oscillator Tolerance and Edge Deviations – A. Mutter, iCC 2013 Paris ���������������������������������������������� 3 Marc Schreiner, International CAN Conference 2015, Vienna
������������������ ���������������������������� scope Tx1 (trigger) receiver receiver trigger once at all nodes Node 2 Node 2 scope bus 2 Node 1 Node 1 Node 3 Node 3 Node 4 Node 4 Node 5 Node 5 Node 6 Node 6 scope bus 1 scope RX1 scope RX2 E SE S Node 1 Node 1 diff TX TX diff TX TX CAN_H CAN_H E SE Node 2 Node 2 S µC CAN topology µC CAN_L CAN_L under test RX RX RX RX Node 3 Node 3 measure once at all nodes for all trigger positions Node 4 Node 4 transmitter transmitter CAN node 1 CAN node 1 Node 5 Node 5 TX TX TX TX CAN_H CAN_H µC µC Node 6 Node 6 CAN_L CAN_L RX RX RX RX result: matrix with n² measurements CAN node n CAN node n-1 4 Marc Schreiner, International CAN Conference 2015, Vienna
�������������������������� ���������� ����������������������������������������������� bit size based on real RX signal 4 logic transmitted TX logic received RX RX / TX signal (V) 3 TX 2 RX 1 virtual RX signal 0 based on bus signal 3 differential bus signal at receiver 0.5V/0.9V transceiver thresholds differential bus signal (V) 2 ringing! ringing! 900mV CAN bus 1 500mV 0 ringing! -1 t(s) 7 1 5 0 µ 7 1 7 5 µ 7 2 0 0 µ 7 2 2 5 µ 7 2 5 0 µ 7 2 7 5 µ 7 3 0 0 µ 7 3 2 5 µ 7 3 5 0 µ 7 3 7 5 µ , , , , , , , , , , 5 Marc Schreiner, International CAN Conference 2015, Vienna
������������������������������������� ������������� Node 2 Node 1 Node 3 Node 4 Node 5 Node 6 Node 1 Node 2 TX evaluation based on real RX signal evaluation based on virtual RX signal Node 3 loopback signal loopback signal Node 4 160n 160n CAN bus RX Node 5 asymmetrty (s) asymmetrty (s) 120n 120n Node 6 PM1, PM2 PM1, PM2 2 nodes 2 nodes safety margin 80n 80n safety margin 3 nodes 3 nodes 4 nodes 4 nodes 5 nodes 5 nodes 40n 40n 6 nodes 6 nodes safe topologies safe topologies 7 nodes 7 nodes 8 nodes 8 nodes 0 0 communication communication between nodes 200n 200n between nodes 160n 160n asymmetry (s) asymmetry (s) 120n 120n 2 nodes 2 nodes PM1, PM2 PM1, PM2 3 nodes 3 nodes 80n 80n 4 nodes 4 nodes safety margin safety margin 5 nodes 5 nodes 6 nodes 6 nodes 40n 40n safe topologies safe topologies 7 nodes 7 nodes 8 nodes 8 nodes 0 0 0 20 40 60 80 100 120 0 20 40 60 80 100 120 total bus length (m) total bus length (m) 6 Marc Schreiner, International CAN Conference 2015, Vienna
�����������������������!������� 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. 7 Marc Schreiner, International CAN Conference 2015, Vienna
"��������"�����#��$ R X e a u a o n b a e d o n e a g n a evaluation based on virtual RX signal v s s t r l i l i l 350n 350n loopback signal loopback signal 300n 300n both-sided term. both-sided term. asymmetry (s) asymmetry (s) 250n 250n onesided term. onesided term. 200n 200n 150n 150n 100n 100n 50n 50n 0 0 200n 200n communication A → B communication A → B both-sided term. both-sided term. 160n 160n onesided term. onesided term. asymmetry (s) asymmetry (s) 120n 120n 80n 80n 40n communication stopped at 40n communication stopped at 32m with test baudrate due to 32m with test baudrate due to high loop back asymmetry high loop back asymmetry 0 0 0 20 40 60 80 100 120 0 20 40 60 80 100 120 transmission line length (m) transmission line length (m) 8 Marc Schreiner, International CAN Conference 2015, Vienna
#�������������������������������������� evaluation based on real RX signal evaluation based on virtual RX signal 2 nodes loopback signal loopback signal 2 nodes 160n 160n 3 nodes 3 nodes 4 nodes asymmetry increasing 4 nodes asymmetrty (s) asymmetrty (s) 5 nodes with number of nodes 5 nodes 120n 120n 6 nodes 6 nodes 7 nodes 7 nodes 8 nodes 8 nodes 80n 80n 12 nodes 12 nodes 14 nodes 14 nodes 16 nodes 40n 40n 0 0 communication communication between nodes 200n 200n between nodes 160n 160n 2 nodes asymmetry increasing asymmetry (s) asymmetry (s) 3 nodes 2 nodes with number of nodes 4 nodes 3 nodes 120n 120n 5 nodes 4 nodes 6 nodes 5 nodes 80n 80n 7 nodes 6 nodes 8 nodes 7 nodes 12 nodes 8 nodes 40n 40n 14 nodes 12 nodes asymmetry increasing 16 nodes 14 nodes with bus length 0 0 0 20 40 60 80 100 120 0 20 40 60 80 100 120 total bus length (m) total bus length (m) 9 Marc Schreiner, International CAN Conference 2015, Vienna
%��������������������&�����������#����� evaluation based on real RX signal evaluation based on virtual RX signal 1 stub 1 stub loopback signal loopback signal 600n 600n 2 stubs 2 stubs ls ≤ 2m asymmetry increasing with 3 stubs 3 stubs 500n 500n asymmetrty (s) asymmetrty (s) number of stubs and stub length 4 stubs 4 stubs 5 stubs 5 stubs 400n 400n � 6 stubs 6 stubs � � ls = 0,25 m ls ≤ 1m 300n 300n � � ls = 0,5 m � � � ls = 1 m 200n 200n ls ≤ 0,5m � ls = 2 m � ls = 4 m 100n 100n ls ≤ 0,25m 0 0 communication between nodes 1 stub 1 stub communication between nodes 600n 600n 2 stubs 2 stubs ls ≤ 2m 3 stubs 3 stubs 500n 500n asymmetry increasing with 4 stubs 4 stubs number of stubs and stub length asymmetry (s) 5 stubs asymmetry (s) 5 stubs 400n 400n 6 stubs 6 stubs � ls = 0,25 m ls ≤ 1m � � 300n 300n � � � � ls = 0,5 m � ls = 1 m 200n 200n � ls = 2 m ls ≤ 0,5m � ls = 4 m 100n 100n ls ≤ 0,25m 0 0 0 20 40 60 0 20 40 60 main bus length (m) main bus length (m) 10 Marc Schreiner, International CAN Conference 2015, Vienna
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