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FlexRay - Bus Guardian | Cypress Semiconductor

FlexRay - Bus Guardian

 Background |  Overview |  Features |  In-car Communication Protocol |  Target applications |  Data transfer method |  Difference with CAN |  Internal configuration of a node |  Electronic signals |  Bus Guardian |  Topology |  Segment configuration |  Protocol |  Status transition |  Error control |

FlexRay ASSP

The bus guardian (BG) in FlexRay performs management of schedules and data independently from the communication controller (CC).

The bus guardian (BG) monitors timing independently.

If a gap in timing is found, it sends a signal to prohibit the bus driver (BD) from sending to protect the bus status. Simultaneously, it notifies the host of the error.

 Configuration diagram of a node in FlexRay

Bus Guardian

 Segment configuration of FlexRay and effective area of Bus Guardian

Segment configuration of FlexRay

The above figure shows a general segment configuration of FlexRay, and the effective area of the bus guardian (BG) is limited to the static segment. This is because the slot length and timing of sending have been determined in the static segment and they cannot be protected by the bus guardian (BG). Also, the dynamic segment works with event triggers (flexible time triggers) and the timing cannot be monitored by the bus guardian (GB).

For more information about segment configuration, see "FlexRay segment configuration."

- Note -

Some parts of this site show only the outlines of the actual FlexRay standards to make them easily understood.