LIN demonstration software

AN4178

8/13

Doc ID 23745 Rev 1

4.2

STM8AF LIN master software description

4.2.1

STM8AF peripherals

The following STM8AF peripherals are used by the application:

●

SPI, which is used in master mode at 250 kHz to initialize the L99PM62GPX and

refresh its watchdog

●

TIM4, which allows generation of a 1 ms timebase

●

HSE, the High Speed External Clock, which when enabled allows the use of the

external 16 MHz crystal oscillator

●

LINUART, which is used to perform LIN communication in master mode

●

GPIO:

–

PA3, PD3, PD0, PE3 and PC3 ports are used for LED display.

–

PE2 and PE1 are used for the USER1 and USER2 push buttons.

–

PC7, PC6, PC5 and PE5 are used respectively for the SPI MISO, MOSI, SCK and

NSS.

–

PD5 and PD6 are used for LINART TX and RX.

4.2.2

Software modules

main

This module contains the initialization routines and the main loop.

appli

This module contains the application’s main tasks:

●

reading the status of the USER1 and USER2 buttons, and updating the corresponding

signals in the LIN frame that will be sent to the STM8AF LIN slave board

●

updating the status of the LEDs according to the signals read in the LIN frame received

from the STM8AF LIN slave board

If the LIN communication is broken, the application will switch on the red LD3 LED.

l99pm62drv

This module contains the driver for the L99PM62GXP device, which is controlled by the

STM8AF microcontroller through SPI.

If the L99PM62GXP device reports an error to the STM8AF through SPI, the software will

switch on the red LD3 LED. The other LEDs will give additional information as follows:

●

LD4 on: SPI error

●

●

LD6 on: thermal shutdown

lin

This module contains the LIN driver state machine described in Section 2.2.1: LIN state

machine.