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_EFrie
_EFrie
Senior
January 30, 2020
Question

STM32F7 ADC external TIM1 trigger

  • January 30, 2020
  • 6 replies
  • 1453 views

Is it possible to externally trigger the ADC in group conversion mode + DMA continually? Nothing I have tried seems to work. It appears that I have to call a software conversion for each synced conversion?

```

 LL_ADC_REG_SetTriggerSource(ADC1, LL_ADC_REG_TRIG_EXT_TIM1_TRGO2);

 LL_ADC_REG_SetContinuousMode(ADC1, LL_ADC_REG_CONV_SINGLE);

 LL_ADC_REG_SetDMATransfer(ADC1, LL_ADC_REG_DMA_TRANSFER_UNLIMITED);

 LL_ADC_REG_SetSequencerLength(ADC1, LL_ADC_REG_SEQ_SCAN_ENABLE_8RANKS);

 LL_ADC_SetSequencersScanMode(ADC1, LL_ADC_SEQ_SCAN_ENABLE);

 LL_ADC_REG_SetSequencerRanks(ADC1, LL_ADC_REG_RANK_1, LL_ADC_CHANNEL_8);

 LL_ADC_REG_SetSequencerRanks(ADC1, LL_ADC_REG_RANK_2, LL_ADC_CHANNEL_5);

 LL_ADC_REG_SetSequencerRanks(ADC1, LL_ADC_REG_RANK_3, LL_ADC_CHANNEL_9);

 LL_ADC_REG_SetSequencerRanks(ADC1, LL_ADC_REG_RANK_4, LL_ADC_CHANNEL_6);

 LL_ADC_REG_SetSequencerRanks(ADC1, LL_ADC_REG_RANK_5, LL_ADC_CHANNEL_13);

 LL_ADC_REG_SetSequencerRanks(ADC1, LL_ADC_REG_RANK_6, LL_ADC_CHANNEL_0);

 LL_ADC_REG_SetSequencerRanks(ADC1, LL_ADC_REG_RANK_7, LL_ADC_CHANNEL_12);

 LL_ADC_REG_SetSequencerRanks(ADC1, LL_ADC_REG_RANK_8, LL_ADC_CHANNEL_4);

 LL_ADC_SetChannelSamplingTime(ADC1, LL_ADC_CHANNEL_0, SAMPLING_CYCLES);

 LL_ADC_SetChannelSamplingTime(ADC1, LL_ADC_CHANNEL_4, SAMPLING_CYCLES);

 LL_ADC_SetChannelSamplingTime(ADC1, LL_ADC_CHANNEL_5, SAMPLING_CYCLES);

 LL_ADC_SetChannelSamplingTime(ADC1, LL_ADC_CHANNEL_6, SAMPLING_CYCLES);

 LL_ADC_SetChannelSamplingTime(ADC1, LL_ADC_CHANNEL_8, SAMPLING_CYCLES);

 LL_ADC_SetChannelSamplingTime(ADC1, LL_ADC_CHANNEL_9, SAMPLING_CYCLES);  

 LL_ADC_SetChannelSamplingTime(ADC1, LL_ADC_CHANNEL_12, SAMPLING_CYCLES);

 LL_ADC_SetChannelSamplingTime(ADC1, LL_ADC_CHANNEL_13, SAMPLING_CYCLES);

 LL_ADC_EnableIT_OVR(ADC1);

 LL_ADC_Enable(ADC1);

/* Setup Timer 1 */

 NVIC_SetPriority(TIM1_UP_TIM10_IRQn, 2);

 NVIC_EnableIRQ(TIM1_UP_TIM10_IRQn);

 LL_TIM_SetPrescaler(TIM1, 0);

 LL_TIM_SetAutoReload(TIM1, SystemCoreClock / (FADER_PWM_HZ * FADER_PWM_RESOLUTION));

  /* Setup Channel 2 for adc trigger */

 LL_TIM_OC_SetMode(TIM1, LL_TIM_CHANNEL_CH2, LL_TIM_OCMODE_FROZEN);

 LL_TIM_OC_SetCompareCH2(TIM1, SystemCoreClock / (FADER_PWM_HZ * FADER_PWM_RESOLUTION) / 2);

 LL_TIM_CC_EnableChannel(TIM1, LL_TIM_CHANNEL_CH2);

 /* Enable update */

 LL_TIM_EnableIT_UPDATE(TIM1);

  

 LL_TIM_SetRepetitionCounter(TIM1, FADER_PWM_RESOLUTION * (FADER_PWM_HZ / FADER_PID_HZ));

 /* Enable counter */

 LL_TIM_EnableCounter(TIM1);

LL_ADC_REG_SetTriggerSource(ADC1, LL_ADC_REG_TRIG_EXT_TIM1_CH2);

```

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6 replies

waclawek.jan
waclawek.jan
Super User
January 30, 2020

Doesn't using CHx from advanced timer require to enable it also by setting TIMx_BDTR.MOE?

JW

_EFrie
_EFrieAuthor
Senior
January 30, 2020

I don't claim to understand it, but it would seem to me like maybe that is about GPIO outputs? I tried it here, setting the AOE bit, It doesn't go, it must be something else.

waclawek.jan
waclawek.jan
Super User
January 31, 2020

I said, MOE, not AOE.

Read back and check the content of timer and ADC registers.

You may also want to try a different timer, some of the "general purpose" ones.

JW

_EFrie
_EFrieAuthor
Senior
January 31, 2020

Not sure what to say, the datasheet says MOE not directly writeable. Anyway, readback does show MOE on. Or, perhaps there is some nuance I'm not getting.

Unfortunately, I am already using timer this to dma pwm gpio, and it really needs to be synchronized to it.

waclawek.jan
waclawek.jan
Super User
January 31, 2020

> Not sure what to say, the datasheet says MOE not directly writeable.

Then you must have a different datasheet (here: Reference Manual) than I have.

0690X00000BxAPSQA3.png

Anyway - read out and check all TIMx registers. Check that it's running and generating a waveform on the given channel - assign it to an appropriate pin in GPIO and observe using oscilloscope.

Read out also the ADC registers and check if they are properly set.

> Unfortunately, I am already using timer this to dma pwm gpio, and it really needs to be synchronized to it.

Okay; but you can use a different timer just to test if the concept is OK. In case you hit troubles like these, you should start with a minimal example anyway, to exclude external influences; and if you get it going then gradually add other features.

JW

_EFrie
_EFrieAuthor
Senior
January 31, 2020

Coming back to this, I'm not sure how to actively use CHx, but I did get TRGO2 to work in this fasion:

```

 LL_ADC_REG_StartConversionExtTrig(ADC1, LL_ADC_REG_TRIG_EXT_FALLING);

 LL_TIM_OC_SetMode(TIM1, LL_TIM_CHANNEL_CH2, LL_TIM_OCMODE_TOGGLE);//<-- This has to toggle so the thing will fire

 LL_TIM_SetTriggerOutput2(TIM1, LL_TIM_TRGO2_OC2);

```

The datasheet for the timers could be improved, stuff is pretty vague.

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