AN3265

Software description

Doc ID 17860 Rev 1

13/19

triggers an interrupt and launches the CLK_IRQHandler() routine. CSS_flag is set and

the application goes to step 3 (SystemState = 2).

3.

SystemState = 2

Pressing Button1 triggers an interrupt. The ButtonPressed flag is set by the

PortB_IRQHandler() routine, and a software reset is generated to disable the CSS (see

Section 2.3.2: Interrupt function flowcharts).

SystemState value is saved in the data EEPROM before the reset occurs.

4.

SystemState = 3

LD4 blinks. The HSE clock is set to the master clock source and the CSS is disabled to

demonstrate how the IWDG can be used to solve microcontroller hardware or software

failures.

Pressing Button2 for longer than the IWDG refresh window (1.02 s) stops the

application by simulating a master clock source failure. After the refresh period has

elapsed, the IWDG resets the STM8S105C6T6, and the application is re-initialized

(SystemState = 0).

Figure 5 shows the flowchart of the State_Machine() function.