lin_stack_master#
Overview#
The LIN (Local Interconnect Network) stack demo applications demonstrate signal transfer between two nodes, master node and slave node. And the lin_stack_master demo is used to demonstrate how to use the lin stack as master node. Both master and slave node must have implemented the timer that is used by timeout service routine every 500 us and master node uses the same timer to check for switch of the frame table scheduler every 5 ms, but the real period between frames may be larger than 5ms according to the configurations.
At startup, the master performs a LIN diagnostic READ_BY_IDENTIFIER exchange to identify the slave node. It queues the request via the transport layer (
ld_read_by_id) and the Lin stack automatically injects the master-request frame (PID 0x3C) at normal-schedule-table boundaries using DIAG_INTERLEAVE_MODE. The master then waits for the slave-response frame (PID 0x3D). If the exchange succeeds, the slave’s supplier ID, function ID, and variant are printed to the console; if no response is received within the timeout the error status is logged and motor control starts regardless.The master node is in NormalTable schedule table and it uses the LIN frame Motor1State_Cycl to receive data from slave node and send selection signal Motor1Selection command to slave node by Motor1Control.
If value from slave is higher than MOTOR1_STOP_VALUE, master will send STOP command to slave node, and LED 3 is on.
If value from slave is higher than MOTOR1_MAX_VALUE, master will send decrease command to slave, and LED 1 is on.
If value from slave is lower than MOTOR_MIN_VALUE, master will send increase command to slave, and LED 2 is on.
The value from slave will keep changing between MOTOR1_MAX_VALUE and MOTOR_MIN_VALUE after reset, unless user press slave button 1 to force the value to MOTOR1_STOP_VALUE.
After master sends stop command, user can press the slave button 2 to set the tick count to 20 to restart the loop.
If the master button 1 was pressed, the master will switch the schedule table to sleep table to send go to sleep signal to slave node.
If the master button 2 was pressed while master in sleep mode, a wake-up signal will be sent by the master node to wake up LIN cluster.
Once running successfully, the state of LEDs on master node and slave node will keep aligned.
If master button 2 was pressed while the bus is already awake, the master sends a LIN 2.1 Sporadic frame with an indicator in bit 2 of the Motor1Control byte. This causes MOTOR1_STOP_VALUE to be incremented by 10 on both the master and the slave. Each additional press while the bus is awake raises the threshold by another 10. MOTOR1_STOP_VALUE resets to the default (150) on both nodes after a sleep/wake cycle.
The schedule includes a LIN 2.1 Event-triggered frame slot. The master sends the ETF header every schedule cycle. If the slave has a pending event, in this demo it is when slave button 1 is pressed 5 times, it responds with the PID of its associated unconditional frame followed by the event data. The master decodes the response, reads the error code and value signals, and prints them to the console.
Running the demo#
If communication is successful, the master node will print:
LIN master demo start.
LIN master will receive data from slave node, and send control command to slave.
Diagnostic: reading slave node identity...
Diagnostic: slave identified - Supplier=0x001E Function=0x0001 Variant=0x00
Diagnostic complete. Starting motor control.
-> LED 2 is ON!
-> LED 1 is ON!
-> LED 2 is ON!
-> LED 1 is ON!
<press slave button 1>
-> LED 3 is ON!
<press slave button 2>
-> LED 2 is ON!
<press master button 2>
Sporadic frame sent: MOTOR1_STOP_VALUE raised to 160
-> LED 1 is ON!
........
<after pressing slave button 1 5 times>
Event-triggered frame received: ErrorCode=0x 1 ErrorValue=0x 5