RESOLVED: TIM3 - 50 Hz pulse

selmesal · ‎2016-10-12

Posted on October 13, 2016 at 00:41

Hello,

Will the following generate a 50 Hz pulse?

(Since htim3.Init.Period = 19999 which I think equates to ~20ms)

htim3.Instance = TIM3;

htim3.Init.Prescaler = 83;

htim3.Init.CounterMode = TIM_COUNTERMODE_UP;

htim3.Init.Period = 19999;

htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

if (HAL_TIM_Base_Init(&htim3) != HAL_OK)

{

Error_Handler();

}

Thanks,

Sel

selmesal · ‎2016-10-12

Posted on October 13, 2016 at 03:34

I have an update.

On the scope, I see 3.7 Hz.

I would appreciate any feedback on how TIM works (and how to achieve 50 Hz)

Thanks,

Sel

selmesal · ‎2016-10-12

Posted on October 13, 2016 at 04:00

Looks like I can play with htim3.Init.Prescalar, Period, and sConifigOC.Pulse to manipulate the waveform properties (Frequency and Duty cycle).

At this point, I am just turning the knobs without a clear understanding all the dependencies and how to calculate the outcome.

I tried a setting with Prescaler = 16, Period = 7499, and Pulse=800 and was able to see a 50 Hz waveform with close to 10% duty cycle.

But, it appears it is not stable and the waveform keeps collapsing (and I have to reset the board).

Walid FTITI_O · ‎2016-10-13

Posted on October 13, 2016 at 11:11

Hi Sel,

To let other users in Forum helping you , try to share details abbout your request:

Which device you are using ?

Which board ?

Wich library you use ? which version ?

you shoud share code or part of it (as TIM configuration)

-Hannibal-

selmesal · ‎2016-10-13

Posted on October 13, 2016 at 23:18

Hi Hannibal,

Thanks.

I am trying to vary PWM width (duty cycle) as shown in the while loop below.

I am using STM32F407VGTx (on the STM32F4 Discovery board).

Here is the version information:

@file stm32f4xx_hal_tim.h

* @author MCD Application Team

* @version V1.5.2

* @date 22-September-2016

* @brief Header file of TIM HAL module.

Here is the code I have in main.c:

int main(void)

{

/* MCU Configuration----------------------------------------------------------*/

/* Reset of all peripherals, Initializes the Flash interface and the Systick. */

HAL_Init();

/* Configure the system clock */

SystemClock_Config();

/* Initialize all configured peripherals */

MX_GPIO_Init();

MX_TIM3_Init();

HAL_TIM_Base_Start(&htim3);

HAL_TIM_PWM_Start(&htim3, TIM_CHANNEL_2);

MX_USART2_UART_Init();

//Trying to step through various duty-cycle values

while (1)

{

HAL_Delay(1000);

sConfigOC.Pulse = 100;

HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_2)

HAL_Delay(1000);

sConfigOC.Pulse = 400;

HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_2)

HAL_Delay(1000);

sConfigOC.Pulse = 800;

HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_2)

}

/* TIM3 init function */

static void MX_TIM3_Init(void)

{

TIM_ClockConfigTypeDef sClockSourceConfig;

TIM_MasterConfigTypeDef sMasterConfig;

TIM_OC_InitTypeDef sConfigOC;

htim3.Instance = TIM3;

htim3.Init.Prescaler = 16;

htim3.Init.CounterMode = TIM_COUNTERMODE_UP;

htim3.Init.Period = 7499;

htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

if (HAL_TIM_Base_Init(&htim3) != HAL_OK)

{

Error_Handler();

}

sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;

if (HAL_TIM_ConfigClockSource(&htim3, &sClockSourceConfig) != HAL_OK)

{

Error_Handler();

}

if (HAL_TIM_PWM_Init(&htim3) != HAL_OK)

{

Error_Handler();

}

sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;

sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;

if (HAL_TIMEx_MasterConfigSynchronization(&htim3, &sMasterConfig) != HAL_OK)

{

Error_Handler();

}

sConfigOC.OCMode = TIM_OCMODE_PWM1;

sConfigOC.Pulse = 800;

sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;

sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;

if (HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_2) != HAL_OK)

{

Error_Handler();

}

HAL_TIM_MspPostInit(&htim3);

}

Walid FTITI_O · ‎2016-10-17

Posted on October 17, 2016 at 19:29

Hi Sel,

If you want to modify the PWM on the fly, you ought to do thatin interruption. In case, you want that in a programmable delay, you should use the systick interruption or a timer channel interrupt. In case , you want to control the PWM signal and after a certain number of pulses you dou your modification, you ought to control it using another timer input.

-Hannibal-