Grundlagen FlexRay - Institut für Automatisierungs- und ...
Grundlagen FlexRay - Institut für Automatisierungs- und ...
Grundlagen FlexRay - Institut für Automatisierungs- und ...
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<strong>Gr<strong>und</strong>lagen</strong> <strong>FlexRay</strong> BasicsV 1.1 26<br />
Figure 2.22 Principle of offset adjustment<br />
For the offset-adjustment, the cycle start point T i of every Sync Node is derived from the local<br />
oscillator, and is compared to the starting time t on the bus. The resulting offset ΔT offset_i is<br />
just to calculate the adjustment.<br />
The calculation of the offset is done in every cycle, while an adjustment of the value is done<br />
only in odd numbered cycles. In these cycles, the Network Idle Time (NIT) will be shorted or<br />
longer, depending on the calculated value.<br />
Calculating the cycle time of a Sync Node ΔT i , by comparing two successive cycle start times<br />
of node I, we can calculate the derivation ΔT rate_i by subtracting the expected cycle time Δt.<br />
This is used for frequency-adjustment. The adjustment of the frequency is calculated and<br />
applied over two successive cycles.<br />
Bäurle 12.10.2012
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