arbitrary waveform using DMA and timer

[Samuel1]

Hello,

i am trying to generate arbitrary waveform. But it still dose not work. I think it's up to the configuration. I have created a array of 6 words for two waveform patterns to be send to TIM1 channel 1 (TIM1_ARR, TIM1_RCR, TIM1_CCR1) This is how the basics look

uint32_t aSRC_Buffer[6] = { 2000,1,800,3000,2,200}; /// ARR, RCR, CCR1 x 2. But i am just getting a 3.3 V on the PIN.

uint32_t aSRC_Buffer[6] = { 2000,1,800,3000,2,200}; 
 
 
HAL_TIM_DMABurst_WriteStart(&htim1,TIM_DMABASE_ARR, TIM_DMA_TRIGGER,
(uint32_t *)aSRC_Buffer, TIM_DMABURSTLENGTH_3TRANSFERS);

 #DMA​ #DMA​ #TIMER​ 

[waclawek.jan]

Perform the writes to those registers "manually". Does the pin voltage change?

jW

[Samuel1]

​@Community member​  the pin is high because i have set the GPIO Mode to Pull-up

[waclawek.jan]

Well, if you set it to pull up (and presumably as Input?) and you find it high, then it works exactly according to your setting, doesn't it?

What's the problem then?

JW

[Samuel1]

​i am trying to generate Waveform Pattern with DMA and Timer. the DMA should send the Data to the TIM1_CH1. but it dose not work. Somehow i dont see the DMA configuration in the main.c i do not know why. i just can see the following:

static void MX_DMA_Init(void) 
{
  /* DMA controller clock enable */
  __HAL_RCC_DMA2_CLK_ENABLE();
 
  /* DMA interrupt init */
  /* DMA2_Stream5_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(DMA2_Stream5_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMA2_Stream5_IRQn);
 
}

[Samuel1]

HAL_TIM_Base_Start(&htim1);
HAL_TIM_PWM_Start(&htim1,TIM_CHANNEL_1);
HAL_TIM_DMABurst_WriteStart(&htim1,TIM_DMABASE_ARR,TIM_DMA_UPDATE,
(uint32_t *)aSRC_Buffer, TIM_DMABURSTLENGTH_3TRANSFERS);

[waclawek.jan]

Start with getting PWM output on that pin, without DMA.

JW

[S.Ma]

If you want to generate a burst of pulses of different timings on a pin, you select a Timer which can be DMA access for its CHANNEL register. Create the toggle points over the course of a timer period and feed this toggle timestamps cyclically to the channel output compare as toggle point.

The timer period should remain fixed.