STMicroelectronics STM8 User Manual

}
void GPIO_setup(void)
{
GPIO_DeInit(GPIOA);
GPIO_Init(GPIOA, GPIO_PIN_3, GPIO_MODE_OUT_PP_HIGH_FAST);
GPIO_DeInit(GPIOD);
GPIO_Init(GPIOD, ((GPIO_Pin_TypeDef)GPIO_PIN_3 | GPIO_PIN_4), GPIO_MODE_OUT_PP_HIGH_FAST);
}
void TIM2_setup(void)
{
TIM2_DeInit();
TIM2_TimeBaseInit(TIM2_PRESCALER_32, 1000);
TIM2_OC1Init(TIM2_OCMODE_PWM1, TIM2_OUTPUTSTATE_ENABLE, 1000, TIM2_OCPOLARITY_HIGH);
TIM2_OC2Init(TIM2_OCMODE_PWM1, TIM2_OUTPUTSTATE_ENABLE, 1000, TIM2_OCPOLARITY_LOW);
TIM2_OC3Init(TIM2_OCMODE_PWM1, TIM2_OUTPUTSTATE_ENABLE, 1000, TIM2_OCPOLARITY_HIGH);
TIM2_Cmd(ENABLE);
}
Explanation
Again, the CPU and the peripheral clock is set at 2MHz.
CLK_HSIPrescalerConfig(CLK_PRESCALER_HSIDIV8);
CLK_SYSCLKConfig(CLK_PRESCALER_CPUDIV1);
….
….
CLK_PeripheralClockConfig(CLK_PERIPHERAL_TIMER2, ENABLE);
Next, we need to configure the PWM GPIOs as outputs.
void GPIO_setup(void)
{
GPIO_DeInit(GPIOA);
GPIO_Init(GPIOA, GPIO_PIN_3, GPIO_MODE_OUT_PP_HIGH_FAST);
GPIO_DeInit(GPIOD);
GPIO_Init(GPIOD, ((GPIO_Pin_TypeDef)GPIO_PIN_3 | GPIO_PIN_4), GPIO_MODE_OUT_PP_HIGH_FAST);
}
Just like other microcontrollers, PWM generation involves a timer. Here as said TIM2 is that timer. We
need to set time base first before actually configuring the PWM channels.
void TIM2_setup(void)
{
TIM2_DeInit();
TIM2_TimeBaseInit(TIM2_PRESCALER_32, 1000);
TIM2_OC1Init(TIM2_OCMODE_PWM1, TIM2_OUTPUTSTATE_ENABLE, 1000, TIM2_OCPOLARITY_HIGH);
TIM2_OC2Init(TIM2_OCMODE_PWM1, TIM2_OUTPUTSTATE_ENABLE, 1000, TIM2_OCPOLARITY_LOW);
TIM2_OC3Init(TIM2_OCMODE_PWM1, TIM2_OUTPUTSTATE_ENABLE, 1000, TIM2_OCPOLARITY_HIGH);
TIM2_Cmd(ENABLE);
}
In the codes above, TIM2 has a time base of 16ms or 62.5kHz. This time base is further divided by the
Output Compare (OC) unit. Thus, here the 62.5kHz base is further divided by 1000 to get 62.5Hz PWM
frequency. The maximum duty cycle is therefore 1000. Additionally, we can set PWM polarity and
command the channel if or if not should it behave in an inverted manner.

STMicroelectronics STM8 Specifications

General

ADC Resolution	10-bit
Core	STM8
Maximum Clock Frequency	Up to 24 MHz
Flash Memory	Up to 128 KB
RAM	Up to 6 KB
EEPROM	Up to 2 KB
Operating Voltage	2.95 V to 5.5 V
Operating Temperature	-40°C to +85°C or +125°C
Communication Interfaces	UART, SPI, I2C
Package Options	LQFP, TSSOP, UFQFPN, SO

Summary

Hardware Tools

Software Tools

Creating a New Code Project

Uploading Code

General Purpose Input Output (GPIO)

Clock System (CLK)

External Interrupt (EXTI)

Alphanumerical LCD

Analog-to-Digital Converter (ADC)

Analog Watchdog (AWD)

Independent Watchdog (IWDG)

Window Watchdog (WWDG)

Time Base Generation (TIM2)

Timer Interrupt (TIM4)

General Purpose Pulse Width Modulation (TIM2 PWM)

Advanced Pulse Width Modulation (TIM1 PWM)

Timer Input Capture (TIM1 & TIM2)

Serial Communication (UART)

Serial Peripheral Interface (SPI)

Inter-Integrated Circuit (I2C)

Peripheral Clock Configurations

Unlocking a Locked STM8 Chip