Application description

AN3260

8/24

Doc ID 17836 Rev 1

3.3

Application principle

At application startup, informative messages are displayed on the terminal window and the

user is prompted to enter critical minimum and maximum temperature thresholds.

The LM235 continuously measures the ambient temperature. The analog value is converted

by the STM8S105C6T6 ADC1 every 50 ms at each timer interrupt. To improve temperature

measurement reliability, temperature data are obtained by averaging the first 16 samples

measured after 1 second has elapsed. The resulting data are then compared to the current

minimum and maximum temperature thresholds which can be modified if needed. LD1 is

switched on if the temperature is below the low threshold or exceeds the high threshold

defined by the user.

Once per minute, the last computed average temperature is displayed on the terminal

window together with the critical temperature warning message when relevant.

The minimum and maximum temperatures over one hour period are recorded in the data

EEPROM once per hour and displayed on the terminal window.

Pressing Button1 prompts the user to enter new temperature threshold values.

Pressing Button2 triggers the display on the terminal window of all recorded minimum and

maximum temperatures stored in data EEPROM. LD1 is switched off.

by the application at each transition. The algorithm that controls the progress of the

execution according to the timer and external events is managed by the State_Machine()