LIN
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SPNU563A–March 2018
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Serial Communication Interface (SCI)/ Local Interconnect Network (LIN)
Module
Following is a sequence of events typical of sleep mode operation:
• The SCI is configured and both sleep mode and receive actions are enabled.
• An address frame is received and a receive interrupt is generated.
• Software compares the received address frame against that set by software and determines that the
SCI is not being addressed, so the value of the SLEEP bit is not changed.
• Several data frames are shifted into SCIRXSHF, but no data is moved to SCIRD and no receive
interrupts are generated.
• A new address frame is received and a receive interrupt is generated.
• Software compares the received address frame against that set by software and determines that the
SCI is being addressed and clears the SLEEP bit.
• Data shifted into SCIRXSHF is transferred to SCIRD, and a receive interrupt is generated after each
data frame is received.
• In each interrupt routine, software checks RXWAKE to determine if the current frame is an address
frame.
• Another address frame is received, RXWAKE is set, software determines that the SCI is not being
addressed and sets the SLEEP bit back to 1. No receive interrupts are generated for the data frames
following this address frame.
By ignoring data frames that are not intended for the device, fewer interrupts are generated. These
interrupts would otherwise require CPU intervention to read data that is of no significance to this specific
device. Using sleep mode can help free some CPU resources.
Except for the RXRDY flag, the SCI continues to update the receiver status flags (see Table 29-13) while
sleep mode is active. In this way, if an error occurs on the receive line, an application can immediately
respond to the error and take the appropriate corrective action.
Because the RXRDY bit is not updated for data frames when sleep mode is enabled, the SCI can enable
sleep mode and use a polling algorithm if desired. In this case, when RXRDY is set, software knows that a
new address has been received. If the SCI is not being addressed, then the software should not change
the value of the SLEEP bit and should continue to poll RXRDY.
29.3 LIN
29.3.1 LIN Communication Formats
The SCI/LIN module can be used in LIN mode or SCI mode. The enhancements for baud generation,
DMA controls and additional receive/transmit buffers necessary for LIN mode operation are also part of
the enhanced buffered SCI module. LIN mode is selected by enabling LIN MODE bit in SCIGCR1 register.
NOTE: The SCI/LIN is built around the SCI platform and uses a similar sampling scheme: 16
samples for each bit with majority vote on samples 8, 9, and 10.
The SCI/LIN control registers are located at the SCI/LIN base address. For a detailed description of each
register, see Section 29.7.
29.3.1.1 LIN Standards
For compatibility with LIN2.0 standard the following additional features are implemented over LIN1.3:
i. Support for LIN 2.0 checksum
ii. Enhanced synchronizer FSM support for frame processing
iii. Enhanced handling of extended frames
iv. Enhanced baud rate generator
v. Update wakeup/go to sleep
The LIN module covers the CPU performance-consuming features, defined in the LIN Specification
Package Revision 1.3 and 2.0 by hardware.
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