stm8s TIM1 PWM not working

[udilevy]

Posted on April 18, 2016 at 14:20

Hi,

I'm trying to operate TIM1 on STM8S003F3P6, I am using the standard peripheral library code, but I am only able to produce pwm on TIM1_CH3 (PC3) pin, the other pins do not produce any waveforms at all. I'm sure this is not a hardware issue- because when I toggle the pin as a gpio- it works fine, what am I missing here?The code is:static void TIM1_Config(void){  /* TIM1 Peripheral Configuration */   TIM1_DeInit();    /* Time Base configuration */ /*  TIM1_Prescaler = 0  TIM1_CounterMode = TIM1_COUNTERMODE_UP  TIM1_Period = 65535  TIM1_RepetitionCounter = 0 */  TIM1_TimeBaseInit(0, TIM1_COUNTERMODE_UP, 65535,0);  /* Channel 1, 2 and 3 Configuration in PWM mode */  /* TIM1_OCMode = TIM1_OCMODE_PWM2  TIM1_OutputState = TIM1_OUTPUTSTATE_ENABLE  TIM1_OutputNState = TIM1_OUTPUTNSTATE_ENABLE  TIM1_Pulse = CCR1_Val  TIM1_OCPolarity = TIM1_OCPOLARITY_LOW   TIM1_OCNPolarity = TIM1_OCNPOLARITY_LOW          TIM1_OCIdleState = TIM1_OCIDLESTATE_SET  TIM1_OCNIdleState = TIM1_OCIDLESTATE_RESET */     TIM1_OC1Init(TIM1_OCMODE_PWM1, TIM1_OUTPUTSTATE_ENABLE, TIM1_OUTPUTNSTATE_DISABLE,               CCR1_Val, TIM1_OCPOLARITY_LOW, TIM1_OCNPOLARITY_LOW, TIM1_OCIDLESTATE_SET,               TIM1_OCNIDLESTATE_RESET);  /* TIM1_Pulse = CCR2_Val */  TIM1_OC2Init(TIM1_OCMODE_PWM2, TIM1_OUTPUTSTATE_ENABLE, TIM1_OUTPUTNSTATE_ENABLE,               CCR2_Val, TIM1_OCPOLARITY_LOW, TIM1_OCNPOLARITY_LOW, TIM1_OCIDLESTATE_SET,               TIM1_OCNIDLESTATE_RESET);  /* TIM1_Pulse = CCR3_Val */ TIM1_OC3Init(TIM1_OCMODE_PWM2, TIM1_OUTPUTSTATE_ENABLE, TIM1_OUTPUTNSTATE_ENABLE,               CCR3_Val, TIM1_OCPOLARITY_LOW, TIM1_OCNPOLARITY_LOW, TIM1_OCIDLESTATE_SET,               TIM1_OCNIDLESTATE_RESET);  /* Automatic Output enable, Break, dead time and lock configuration */  /* TIM1_OSSIState = TIM1_OSSISTATE_ENABLE  TIM1_LockLevel = TIM1_LOCKLEVEL_1  TIM1_DeadTime = 117  TIM1_Break = TIM1_BREAK_ENABLE  TIM1_BreakPolarity = TIM1_BREAKPOLARITY_HIGH  TIM1_AutomaticOutput = TIM1_AUTOMATICOUTPUT_ENABLE */  /* TIM1 counter enable */  TIM1_Cmd(ENABLE);  /* Main Output Enable */  TIM1_CtrlPWMOutputs(ENABLE);} #stm8 #stm8s #tim1-timer

[Todd Phelps]

Posted on January 26, 2018 at 01:22

Were you ever able to get this working? The configuration I had to output PWM on TIM1 CH1,2,3 worked on the stm8svldiscovery board with the 3K3 chip but not on the 3F3 I used on my own board.

[Todd Phelps]

Posted on January 29, 2018 at 18:46

I found the issue, on the 20-pin STM8S003F3 the PWM outputs are an alternate function on the pins. These alternate functions must be activated by setting the Option bytes. In IAR this can be done from the menu option ST-LINK->Option bytes but can also be done in code which is what I've done, using the STM8S peripheral library. After setting the option byte, which happens only during the first run of the device, it appears necessary to reset the microcontroller for the change to take effect. 

#define OPTION_BYTE_AFR                 0x4803   /* Alternate function remapping option byte */

#define AFR0                                          0x01       /* Alternate function remapping bit 0 */

...

verify_option( OPTION_BYTE_AFR, AFR0 ); /* Activate alternate pin func for PWM */

...

void verify_option

    (    uint16_t address,    uint8_t data    ){uint16_t stored_data = FLASH_ReadOptionByte( address );

if( ( FLASH_OPTIONBYTE_ERROR == stored_data ) ||

    ( data != (uint8_t)( stored_data>>8 ) ) )    {    FLASH_Unlock( FLASH_MEMTYPE_DATA );    FLASH_EraseOptionByte( address );    FLASH_ProgramOptionByte( address, data );    FLASH_Lock( FLASH_MEMTYPE_DATA );        /* Use the watchdog to reset the device to enable the feature */    IWDG->KR = IWDG_KEY_ENABLE;    while(1);    }}