LIN Controller (LINFlex)MPC5606S Microcontroller Reference Manual, Rev. 7830 Freescale Semiconductor23.2.3 Features common to LIN and UART• Fractional baud rate generator• 3 operating modes for power saving and configuration registers lock:— Initialization— Normal— Sleep• 2 test modes:— Loopback— Self-test• Maskable interrupts23.3 General descriptionThe increasing number of communication peripherals embedded on microcontrollers, for example CAN,LIN and SPI, requires more and more CPU resources for communication management. Even a 32-bitmicrocontroller is overloaded if its peripherals do not provide high-level features to autonomously handlethe communication.Even though the LIN protocol with a maximum baud rate of 20 kbit/s is relatively slow, it still generatesa non-negligible load on the CPU if the LIN is implemented on a standard UART, as usually the case.To minimize the CPU load in Master mode, LINFlex handles the LIN messages autonomously.In Master mode, once the software has triggered the header transmission, LINFlex does not request anysoftware intervention until the next header transmission request in transmission mode or until thechecksum reception in reception mode.To minimize the CPU load in Slave mode, LINFlex requires software intervention only to:• Trigger transmission or reception or data discard depending on the identifier• Write data into the buffer (transmission mode) or read data from the buffer (reception mode) afterchecksum receptionIf filter mode is activated for Slave mode, LINFlex requires software intervention only to write data intothe buffer (transmission mode) or read data from the buffer (reception mode)The software uses the control, status and configuration registers to:• Configure LIN parameters (for example, baud rate or mode)• Request transmissions• Handle receptions• Manage interrupts• Configure LIN error and timeout detection• Process diagnostic informationThe message buffer stores transmitted or received LIN frames.
