STM32F4 ADC DMA and Timer1 trigger

[Parmin Nayani]

Hello all,

I want to take ADC reading at regular intervals based on timer 1 (used OC mode). The timer must trigger the ADC to take a reading and the ADC in turn will trigger the DMA to transfer the ADC reading to memory. To check that the timer is running I am toggling a GPIO_PIN. This pin toggles but conversion is not getting triggered.

I have enabled one OC1 output pin toggle and that is toggling.  One more point is, the following call triggers one conversion.

HAL_ADC_Start_DMA (&hadc1, (uint32_t *)adc_buf,ADC_BUF_LEN);

I am missing the link to TIM1 OC1 and ADC start conversion whenever the OC1 match occurs. 

Can someone help please? 

Below is the ADC init code.

void MX_ADC1_Init(void)
{
__HAL_RCC_ADC1_CLK_ENABLE();
hadc1.Instance = ADC1;
hadc1.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV8;
hadc1.Init.Resolution = ADC_RESOLUTION_12B;
hadc1.Init.ScanConvMode = DISABLE; //
hadc1.Init.ContinuousConvMode = DISABLE; //
hadc1.Init.DiscontinuousConvMode = ENABLE; //
hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;

hadc1.Init.ExternalTrigConv = ADC_EXTERNALTRIGCONV_T1_CC1; // Is this correct?

hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
hadc1.Init.NbrOfConversion = 1; //
hadc1.Init.DMAContinuousRequests = DISABLE; //
hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
if (HAL_ADC_Init(&hadc1) != HAL_OK)
{
Error_Handler();
}

sConfig.Channel = ADC_CHANNEL_10; //ADC_CHANNEL_VBAT;
sConfig.Rank = 1;
sConfig.SamplingTime = ADC_SAMPLETIME_3CYCLES;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler();
}
}

[Sarra.S]

Hello @Parmin Nayani, 

Could you also share the TIM configuration, your ADC config looks correct (sharing your project would be optimal) 

>>hadc1.Init.ExternalTrigConv = ADC_EXTERNALTRIGCONV_T1_CC1; // Is this correct?

You need to ensure that the ExternalTrigConv is set to the correct timer output compare event, so that's correct if you're using TIM1_CH1

Also, make sure that ExternalTrigConvEdge is set to the appropriate edge (rising, falling, or both) that you want to trigger the conversion. 

You can also check this valuable article: Using Timers to Trigger ADC conversions periodically

[SofLit]

Hello,

• Which STM32F4 part number you're using?
• You need to enable continuous mode on ADC and DMA :

• This is the list of ADC internal triggers for regular channel conversion (from RM0090:(

[Parmin Nayani]

Hello Sarra and SofLit,

Thank you for your replies. I did a check on the ADC_CR2 bits by reading them. I found the value after all the initializations, to be 0x400. Just the EOCS bit is set. So I did a brute force setting of the EXTEN bits by 

ADC1->CR2 |= 0x30000000;   How to set these bits through the HAL call?

After this to start one set of conversions I called -> HAL_ADC_Start_DMA (&hadc1, (uint32_t *)adc_buf,ADC_BUF_LEN);  This seems to convert. TIM1_CH1 event value is 0000 so left it as it is. Sharing the project is no issue but the entire code is in a mess. I have several unused functions etc. I am posting the ADC init code. Here is the timer code

void MX_TIM1_Init(void)

{

GPIO_InitTypeDef GPIO_InitStruct;

TIM_OC_InitTypeDef sConfigOC = {0};

TIM_ClockConfigTypeDef sClockSourceConfig = {0};

TIM_MasterConfigTypeDef sMasterConfig = {0};





/* USER CODE BEGIN TIM2_Init 0 */

__HAL_RCC_TIM1_CLK_ENABLE();



__HAL_RCC_GPIOA_CLK_ENABLE();

/**TIM2 GPIO Configuration

PA5 ------> TIM2_CH1

*/

GPIO_InitStruct.Pin = GPIO_PIN_8;

GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;

GPIO_InitStruct.Pull = GPIO_NOPULL;

GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;

GPIO_InitStruct.Alternate = GPIO_AF1_TIM1;

HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

/* USER CODE END TIM2_Init 0 */

/* USER CODE BEGIN TIM2_Init 1 */

/* USER CODE END TIM2_Init 1 */

htim1.Instance = TIM1;

htim1.Init.Prescaler = 0;

htim1.Init.CounterMode = TIM_COUNTERMODE_UP;

htim1.Init.Period = 10000;

htim1.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

htim1.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE; // shadow register used?

if (HAL_TIM_Base_Init(&htim1) != HAL_OK)

{

Error_Handler();

}



sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;

if (HAL_TIM_ConfigClockSource(&htim1, &sClockSourceConfig) != HAL_OK)

{

Error_Handler();

}



sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;

sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;

if (HAL_TIMEx_MasterConfigSynchronization(&htim1, &sMasterConfig) != HAL_OK)

{

Error_Handler();

}

sConfigOC.OCMode = TIM_OCMODE_TOGGLE; //TIM_OCMODE_TIMING;

sConfigOC.Pulse = 0;

sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;

sConfigOC.OCNPolarity = TIM_OCNPOLARITY_HIGH;

sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;

sConfigOC.OCIdleState = TIM_OCIDLESTATE_RESET;

sConfigOC.OCNIdleState = TIM_OCNIDLESTATE_RESET;

if (HAL_TIM_OC_ConfigChannel(&htim1, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)

{

Error_Handler();

}

}

[SofLit · Accepted solution]

Hello,

I've created a project based on STM32F407-DISCO board on which the ADC is triggered by TIM1-CC1 event. DMA has been used in circular mode to transfer the converted data to the memory.

The converted channel is the internal Temperature sensor.

Hope it helps.

[Parmin Nayani]

Hi SofLit,

Thank you very much for sharing the code. I will go through it and revert if I have any questions. 

[SofLit]

And please close the thread by accepting the solution if you estimate that I answered your original question.