STM8S/A Standard Peripherals Firmware Library: Generate three different signals with three different duty cycles

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  * @file    TIM2/TIM2_PWM_DutyCycleConfiguration/readme.txt
  * @author  MCD Application Team
  * @version V2.2.0
  * @date    30-September-2014
  * @brief   Description of the TIM2 PWM duty cycle configuration mode Example.
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  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
  * You may not use this file except in compliance with the License.
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Example description

This example shows how to configure the TIM2 peripheral in Pulse Width Modulation mode(PWM). The TIM2CLK frequency is 2MHz, the Prescaler is 1 so the TIM2 counter clock is 2MHz.

The TIM2 is running at 2 KHz: TIM2 Frequency = TIM2 counter clock/(ARR + 1)

So TIM2 frequency is 2KHz.

The TIM2 CCR1 register value is equal to 500, so the TIM2 Channel 1 generates a PWM signal with a frequency equal to 2KHz and a duty cycle equal to 50%: TIM2 Channel1 duty cycle = [TIM2_CCR1/(TIM2_ARR + 1)] * 100 = 50%

The TIM2 CCR2 register value is equal to 375, so the TIM2 Channel 2 generates a PWM signal with a frequency equal to 2KHz and a duty cycle equal to 25%: TIM2 Channel2 duty cycle = [TIM2_CCR2/ (TIM2_ARR + 1)] * 100 = 25%

The TIM2 CCR3 register value is equal to 250, so the TIM2 Channel 3 generates a PWM signal with a frequency equal to 2KHz and a duty cycle equal to 12.5%: TIM2 Channel3 duty cycle = [TIM2_CCR3/ (TIM2_ARR + 1)] * 100 = 12.5%

The PWM waveform can be displayed using an oscilloscope.

Directory contents

• TIM2\TIM2_PWM_DutyCycleConfiguration\main.c Main file containing the "main" function
• TIM2\TIM2_PWM_DutyCycleConfiguration\stm8s_conf.h Library Configuration file
• TIM2\TIM2_PWM_DutyCycleConfiguration\stm8s_it.c Interrupt routines source
• TIM2\TIM2_PWM_DutyCycleConfiguration\stm8s_it.h Interrupt routines declaration

Hardware and Software environment

• This example runs on STM8S and STM8A High density, Medium density devices and STM8S103x Low density devices.

• This example has been tested with STMicroelectronics STM8/128-EVAL evaluation board and can be easily tailored to any other development board.

• STM8/128-EVAL Set-up
  • Connect TIM2 pins to an oscilloscope:
    • TIM2_CH1 pin (PD.4)
    • TIM2_CH2 pin (PD.3)
    • TIM2_CH3 pin (PA.3)

How to use it ?

In order to make the program work, you must do the following :

• Copy all source files from this example folder to the template folder under Project
• Open your preferred toolchain
• Rebuild all files and load your image into target memory
• Run the example
• Connect the TIM2 pins to an oscilloscope

Note:

• High-Density STM8A devices are the STM8AF52xx STM8AF6269/8x/Ax, STM8AF51xx, and STM8AF6169/7x/8x/9x/Ax microcontrollers where the Flash memory density ranges between 32 to 128 Kbytes
• Medium-Density STM8A devices are the STM8AF622x/4x, STM8AF6266/68, STM8AF612x/4x, and STM8AF6166/68 microcontrollers where the Flash memory density ranges between 8 to 32 Kbytes
• High-Density STM8S devices are the STM8S207xx, STM8S007 and STM8S208xx microcontrollers where the Flash memory density ranges between 32 to 128 Kbytes.
• Medium-Density STM8S devices are the STM8S105x and STM8S005 microcontrollers where the Flash memory density ranges between 16 to 32-Kbytes.
• Low-Density STM8S devices are the STM8S103xx, STM8S003 and STM8S903xx microcontrollers where the Flash density is 8 Kbytes.

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