L99LDLH32 datasheet(49/142 Pages) STMICROELECTRONICS

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DS12879 Rev 6

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L99LDLH32

Communication interface

141

This wake-up pattern is repeated in the eight data bytes of the frame shown in Table 10. The

Responders recognize the dominant-recessive-dominant pulse in which the three individual

pulses are longer than the specified filter time. These pulses are contained in the data field.

If the frame does not contain any data, it serves as “Go-To-Sleep”-command for all

Responders in the network. If it contains at least one data byte, it acts as a wake-up pattern

for all Responders.

In conclusion:

ID = “1_000_011_1100” & DLC = 0  send-to-sleep command

ID = “1_000_011_1100” & DLC ≠ 0  wake-up pattern frame

6.5.5

Synchronization Frame

The synchronization frame must be sent by the commander after each responder reply, but

only if the addressed devices change in the next commander frame. Due to the frequency

offset between the replying Responder and the Commander some other Responders may

not be able to receive frames sent by the Commander correctly after a Responder answer.

Therefore, the frame in Figure 22 has to be sent by the Commander to ensure correct

synchronization of all Responders to the Commander. The Responders will synchronize on

this frame but drop the content because it does not contain an ID that the Responders

recognize.

Figure 22. Synchronization frame

6.6

Unicast frames

6.6.1

Unicast request frame

The Commander may request action from a particular Responder by sending a unicast

request frame, which uses the Responder ID in the CAN FD ID field preceded by “0” to

distinguish the Commander request from the Responder answer. The MSB of all CAN FD

IDs used for unicast frames in the network is “0” to distinguish between unicast and

broadcast frames.

Table 10. Wake-up pattern (WUP) frame

CTRL

DLC

DATA BYTE 1

DATA BYTE 2-8

“1_000_011_1100”

“001000”

1000

1111_1110

0000_1111

Table 11. Synchronization frame

CTRL

DLC

“1_010_101_0101”

“001000”

0000

„1_010_101_0101"

CTRL

CRC

ACK/EOF

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