AN3397

Software description

Doc ID 018809 Rev 1

15/24

3

Software description

3.1

STM8L peripherals used by the application

The application software uses the standard STM8L firmware library to control the

peripherals. The peripherals and functions used by the application software are listed below:

Clock

The HSI (high speed internal) 16 MHz oscillator is selected as clock source:

●

System clock divider = 0

●

LCD controller

The LCD controller drives the LCD glass mounted on the DISCOVERY board. It is interfaced

using 24 segment lines and four common lines, and is configured as follows:

●

CLK (PSC = 1 and DIV = 31)

●

Duty = 1/4

●

Bias = 1/3

●

LCD voltage source = internal

●

Contrast = 3.10 V

●

No dead time

●

Pulse on duration = 1

ADC

The ADC converts the TS output voltage into a digital value. The ADC peripheral is

configured as follows:

●

ADON = 1 and TSON = 1

●

Single conversion mode

●

12-bit resolution

●

●

●

TS channel selected

Real-time clock (RTC)

The RTC generates the time base for waking up the microcontroller from low power Active-

halt mode. The RTC peripheral is configured as follows:

●

Low-speed external (LSE) clock selected as RTC clock source by default. The low-

speed internal (LSI) clock can also be used by removing the USE_LSE definition in the

project options.

●

RTC clock prescaler = RTC clock source/1

●

Wakeup clock selection bits, WUCKSEL[2:0], are set to 000: RTCCLK/16 to generate

an RTC counter timebase of approximately 500 µs

●

Wakeup counter registers, WUTRx, are set to 100 to generate a 50 ms wakeup time