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1391

Module Operation

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26.2.1.1.1.3 Transfer Reset

The Transfer Unit State Machine can be reset by the Transfer Unit Enable (TUE) bit in the Global Control

contents and the Transfer Configuration RAM (TCR). So, after re-enabling the Transfer Unit no

reconfiguration of the Transfer Unit is required.

26.2.1.1.1.4 Transfer Modes

Possible transfer sequence modes are:

• Manual by triggering the desired transfer by setting the corresponding bit in the Trigger Transfer to

System Memory (TTSM) register or the Trigger Transfer to Communication Controller (TTCC) register

• Event-Driven (transfers from FlexRay Communication Controller to the System Memory only) using the

Enable Transfer on Event to System Memory (ETESM) register.

• Single or continuous event driven transfers by using the Clear on Event to System Memory (CESM)

The transfer event trigger in general occurs upon completion of a reception or transmission of a frame

through the FlexRay bus. Table 26-2 shows more details: Conditions marked with 'X' per row must match

to trigger a FTU transfer event as configured in the Transfer Configuration RAM (TCR):

Table 26-2. FlexRay Transfer Unit Event Trigger Conditions

Frame belonging

Frame belonging to dynamic Bus activity Bus activity

to static segment segment, except detected on detected on

Event on Event on or first slot of first slot of Channel A Channel B

Channel A Channel B dynamic segment dynamic segment (MBS.ESA = 0) (MBS.ESB = 0)

X X

FTU Event Trigger

X X

for Receive

X X X

Message Buffers

X X X

FTU Event Trigger X X

for Transmit

X X

Message Buffers

NOTE: By setting the corresponding bit in the Enable Transfer on Event to System Memory

(ETESM) register prior to a on-demand transfer to the Communication Controller via the

Trigger Transfer to Communication Controller (TTCC) register, an event triggered

transmission back to the System Memory can be initiated, once the buffer has been sent out

on the FlexRay bus. This mechanism can be used i.e. to automatically read back the header

status information to the system memory after a transmission occurred.

The transmission or reception of null frames in the static segment of a FlexRay

communication cycle triggers transfers of the transfer unit. The header and/or payload is

transferred to the system memory, if the corresponding bits THTSM and/or TPTSM in the

Transfer Configuration RAM (TCR) are set. If neither THTSM nor TPTSM bit is set in TCR,

neither header nor payload gets transferred. The corresponding bit in the Transfer to System

Memory Occurred register (TSMO) gets set in all cases.

1162

FlexRay Module SPNU563–May 2014

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