Sharing | TSMaster-LIN Wake and Sleep Mechanisms

Common wake-up methods in automotive bus are hardwire wake-up, network wake-up and specific signal wake-up, while LIN bus is realized by sleep frame and wake-up level, this article will introduce the wake-up and sleep mechanism of LIN.

KEYWORDS IN THIS ARTICLE: LIN Network Management, Hibernate, Wake Up

Table of Contents for this article

01. Network management

In the LIN2.1 protocol, network management refers to the sleep and wake-up management of the network, and Figure 1 shows the communication status of LIN slave nodes.

initialization: Entering this state after reset and wake-up, the slave node will perform the necessary initialization and then enter the working state. Initialization here means LIN related initialization, reset and wake up means are different initialization while initialization is done within 100ms.

(of a machine) operate: LIN messages are sent and received on the LIN network.

Bus Sleep Mode: The invisible level is held on the LIN bus and only the wake-up level can appear on the LIN bus.

02. Awakening

Any one of the nodes (master and slave) in the dormant LIN network can send a wake-up level to wake up the LIN network, which lasts for 250us~5ms. the other nodes should detect pulses greater than 150us and be ready to listen to the LIN bus within 100ms, i.e., they should be ready to receive headers from the master node within 100ms from the end of the pulses as shown in Figure 2. shown; if the wake-up level is sent from the node, it will be ready to receive the message header or transmit the message immediately, and the master node must also send the frame header within 100ms to start the communication.

If the bus does not receive any frame information within 150ms~250ms after sending the wake-up level, the node sending the wake-up level should send a new wake-up signal, and the wake-up signal can be sent up to three times, as shown in Figure 3:

If after three failed wakeup requests, the node should wait for at least 1.5 s. Then a fourth wakeup level is issued. As shown in Fig. 4:

To meet the above requirements, TSMaster provides a WakeUp level signal parameter configuration module, as shown in Figure 5:

Wake-up level length = 1000000/Baudrate*(BitNum), for example, if the baud rate is 19.2k and BitNum = 5 is set, the level width is 260.4, as shown in Figure 6:

When Tirgger Times is set equal to 3 and Trigger Interval time is equal to 3ms, then TSMaster will send multi-frame wake-up messages with message interval equal to 3ms, as shown in Fig. 8, the wake-up level (260.4us) is sent first, and then the wake-up level is sent again after 3ms has passed, and the cycle is sent three times.

03. Dormancy

The LIN bus goes to sleep in two ways:

Using the master node request frame 0x3C of the diagnostic frame for the hibernation command
When there is no stealth and display level switching (4~10s) in the LIN bus, the node automatically enters hibernation; the LIN2.1 protocol specifies that the hibernation message must be sent by the master node, and the content of the hibernation message frame is shown in Figure 9:

In the LIN Send window of TSMaster, as shown in Figure 10, select the node and channel, and then click the Goto Sleep button to view the waveform telegram through the oscilloscope (Figure 11).

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