Posted by bob1 on 2016-03-01 15:55

Hi Ben
Thank you. Without realizing it you have just solved a problem for me by posting your 2nd picture showing your clock tree. It helped because it shows the the TIM peripherals are clocked at 2x the APBx rate of other peripherals.I had to double my prescaler divider without knowing why - now I do know why - thanks.

I Have Just got PWM Output working for channel-1 of General purpose TIM10 of a STM32F407VGt6 to drive a standard Futaba FPS148 servo. I am Using HAL version 1.4.4 in STM32 Cube F4 version 1.11.0. Consequently I will look at your work and see if I can spot any subspace anomalies.

In the meanwhile find attached a working TIM register snapshot. And my initialization code.

For what its worth I had exactly the same NO PWM problem and found that the TIM10->CCMR1(output) register had not been configured - it was 0 when it should have been 0x68. The reason was because the “HOW TO USE” instructions at the top of the stm32f4xx_hal_tim.c had a bullet list of instructions which I WRONGLY assumed contained ONE instruction per bullet - I had missed the 2nd instruction on one bullet to call function HAL_TIM_PWM_ConfigChannel(). It is possible others have missed that too.

To set the PWM level I load TIM10->CCR1 with a number between 1260 and 9660 (centered around 5460) because the servo PWM pulse is only allowed to be high for the first .3ms to 2.3ms of a 15.6ms period (in my application anyway. Officially/generically/typically it’s 1 to 2ms in a 20ms period, says Wiki)

Posted by BenoitHanridge on 2016-03-01 16:20

Hi Bob1,

I suspect CubeMX didn’t include HAL_TIM_PWM_Start to activate the PWM signal.

Greets,
Ben

Posted by BenoitHanridge on 2016-03-01 18:10

Yes Bob1,

I only had to add HAL_TIM_PWM_Start four times for each output. Well that’s solved then.

I again used CubeMX to generate the code necessary to configure one timer for PWM. With the STM32F103C8T6 only TIMER 2,3 and 4 can be configured for PWM. CubeMX did everything except it did not start the PWM hence HAL_TIM_PWM_Start I had to manually add in main.c. I guess there’s also a HAL_TIM_PWM_Stop somewhere to be found otherwise I wouldn’t know why ST created this extra mandatory function (to then forget about it in CubeMX).

Your PWM_SERVO_wkg1.png screenshot was useful in seeing the necessities.

Thx,
Ben

Posted by BenoitHanridge on 2016-03-01 19:40

Additional conclusion: The PWM for what I intended to use it won’t be possible because of the limited frequency range.

A/D resolution needs to be 16 bit, thus the full counter range from 0 to 65535. 72 Mhz counter clock speed ( prescaler and divider both being zero) already brings the max PWM frequency to 72 Mhz / 65536 = approximately 1 khz sample frequency. Dead end. Nevertheless it was intersting.

Greets!

Posted by abdullahbaig on 2016-03-03 09:54

I am also not able to generate PWM on STM32F4 Dicovery. I have tried TIM5 channel 2 and now TIM2 channel. All this code is generated by Cube MX. I am just trying to get any type of PWM out of the STM, it can always be configured and tweeked later. Can anyone point out what I am missing??

I see the green LED blinking on PD12 but the PA1 is all dead. It gives a straight line on the oscilloscope.

pininit() and togglepin() are my own functions.

/**
******************************************************************************
* @file main.c
* @author Ac6
* @version V1.0
* @date 01-December-2013
* @brief Default main function.
******************************************************************************

• /

1. include “stm32f4xx.h”
2. include “stm32f4_discovery.h”
3. include “compact_functions.h”

static void SystemClock_Config(void);
static void MX_TIM2_Init(void);

TIM_HandleTypeDef htim2;

int main(void)
{
HAL_Init();

SystemClock_Config();

pininit_output(GPIOD, 12);
pininit_alt_pp(GPIOA, 1);

MX_TIM2_Init();

__HAL_RCC_TIM2_CLK_ENABLE();
HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_2);

for(;;)
{
togglepin(GPIOD, 12);
delay_ms(2000);
}
}

/** System Clock Configuration

• /

void SystemClock_Config(void)
{

RCC_OscInitTypeDef RCC_OscInitStruct;
RCC_ClkInitTypeDef RCC_ClkInitStruct;

__PWR_CLK_ENABLE();

__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 8;
RCC_OscInitStruct.PLL.PLLN = 336;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 7;
HAL_RCC_OscConfig(&RCC_OscInitStruct);

RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK|RCC_CLOCKTYPE_PCLK1
|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5);

HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);

HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);

/* SysTick_IRQn interrupt configuration */
HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
}

void MX_TIM2_Init(void)
{

TIM_MasterConfigTypeDef sMasterConfig;
TIM_OC_InitTypeDef sConfigOC;

htim2.Instance = TIM2;
htim2.Init.Prescaler = 0;
htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
htim2.Init.Period = 1024;
htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
HAL_TIM_PWM_Init(&htim2);

sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
HAL_TIMEx_MasterConfigSynchronization(&htim2, &sMasterConfig);

sConfigOC.OCMode = TIM_OCMODE_PWM1;
sConfigOC.Pulse = 384;
sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
HAL_TIM_PWM_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_2);
}

void pininit_alt_pp(GPIO_TypeDef *GPIOx, uint32_t pinno)
{
pininit(GPIOx, pinno, GPIO_MODE_AF_PP,GPIO_SPEED_FREQ_LOW,GPIO_NOPULL);
}

Posted by abdullahbaig on 2016-03-03 11:47

My bad, I wasn’t specifying the source GPIO_AF1_TIM2 of the alternate function in pininit().

But I am still amazed why do I have to include the macro _HAL_RCC_TIM2_CLK_ENABLE(); in the main function. Shouldn’t the HAL initilization functions call it? Even the Cube MX doesn’t take care of it. And if I remove it from the code, the timer doesn’t run.