LIN demonstration software

AN4101

16/21

Doc ID 23127 Rev 1

7.3

STM8AL software description

7.3.1

STM8AL peripherals

The following STM8AL 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

●

USART, which is used to perform LIN communication in slave mode

●

GPIO

–

PE7 and PC7 ports are used for LED display.

–

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

–

PB7, PB6, PB5 and PB4 are used respectively for the SPI MISO, MOSI, SCK and

NSS.

–

PC3 and PC2 are used for USART TX and RX.

7.3.2

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 board

●

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

from the STM8AF board

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

display “ERR2” on the LCD screen.

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 STM8AL through SPI, the software will

display “ERR1” on the LCD screen. The LCD bars will give additional information as follows:

●

BAR0 on: SPI error

●

●

BAR2 on: thermal shutdown

lin

This module contains the LIN driver state machine described in Section 6.2.1: LIN state

machine.