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Published byHarry Sanders Modified over 9 years ago
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Q uantitative E valuation of E mbedded S ystems
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TDMA in a cyber physical system: preparation for the SDF3 assignment
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Period = P Slice = S Task = T P-S TP/S
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Period = P Slice = S Task = T P-S q qT = rS S/q rr P-(S/q) 0 NEW!! Publication under submission... RTAS 2014 NEW!! Publication under submission... RTAS 2014
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Comp. Inner control Physical World Comp. Emergency detection Comp. Image processing
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Comp.1 Inner control Comp.2 Emergency detection Comp.3 Image processing
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Comp.1 Inner control Comp.2 Emergency detection Comp.3 Image processing p2 p1 p3 p4 p5 p6 p7 p8 p9 p10 p11 p12 p13 p14 p15 p16 p17 p18
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Comp. Inner control Comp. Emergency detection Comp. Image processing
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Comp. Inner control Comp. Emergency detection Comp. Image processing
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Comp.1 Inner control Comp.2 Emergency detection Comp.3 Image processing
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Latency 1 L2 L3
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Period = P Slice = S Task = T P-S q qT = rS S/q rr P-(S/q) 0
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Period = P Slice = S Task = T qT = rS One packet per slice in the network, therefore T = S = 0.01 ms One slice per node in the network But... each node schedules its routing in a TDMA fashion as well... So for each hop P = (C+1)*N*S where C is the number of connections and N is the total number of nodes in the network.
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Period = P Slice = S Task = T qT = rS Three computations = three slices, so P = S1 + S2 + S3 Task times may be bigger than slice times! T1 = 0.5 ms T2 = 3 ms T3 = 7 ms It is part of the assignment to figure out how P should be chosen and divided over S1,S2 and S3.
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Sensor 1 and 2 produce 1 packet every 2 ms Sensor 3 produces 50 packets every 100 ms Sensor 4 produces 10 packets every 20 ms Computation 1 needs 1 packet from sensor 1 and 2, and produces 1 packet for computation 2 and one for actor 1 Computation 2 takes 50 packets from computation 1 and 1 packet from computation 3 and produces 1 for actors 2 and 3 and for computation 3. Computation 3 takes 50 packets from sensor 3, 50 from sensor 4 and 1 packet from compation 2 and produces 1 for computation 2.
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Sensor1 Sensor2 Sensor3 Sensor4 Actuator1 Actuator2 Actuator3 hop1hop2 hop3 hop4 hop5 hop6 hop7 hop8 hop9 hop10 hop11hop12 hop13 hop14 hop15 Comp1 Comp2 Comp3 1 1 50 10 50 2 ms 100 ms 20 ms 22 2 2 2
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