DMA registers are not set correctly on STM32L052K8T6 Hello, I want to use the DMA to shift data from 9 ADC Channels into an Array. The problem is that I set up the ADC and the DMA in CubeMX. But the Registers of the DMA are not set correctly.

[MMüll.5]

My CubeMX Setup:

DMA:

ADC:

ADC NVIC:

After I had done this, I generated the

Code and Started the ADC and the DMA with the HAL_ADC_Start_DMA function. The

function Started the ADC as I wanted, but the Registers of the DMA are not set

Correctly.

The DMA register, which is not set correctly:

I assumed that the CIRC and the MINC bit should be set, and also the PSIZE should be 0x01 and MSIZE 0x02. Have I done something wrong or what is happening?

If you need some more Information, just say it and I will upload it as fast as possible.

[waclawek.jan]

Cube is open source so you can step through the functions which set the DMA and observe variables and registers to find out where is the problem.

JW

[MMüll.5]

Hi,

I tried to do that, but I could not find where they should get set. I think that could be because they are just left in their standard setting, but the problem is I don't want them to be in that setting.

I think it could be useful to know that when i try to set the Registers to the right value in the debugger, they change back to the value I have shown in the snapshot. Except for the CIRC bit, this stays at the value I set it to.

[waclawek.jan]

> I tried to do that, but I could not find where they should get set.

In the Cube function which sets DMA. Don't "step over" it, "step into". I don't use Cube.

> [...] they change back [...]

Sounds like you are trying to modify registers while the program is running.

JW

[MMüll.5]

I looked in an older project where I used the DMA for something similar. And I compared both of them and found out that the registers I want to set are set in the ADC init, so I looked into that and found some differences. I will try to fix that and tell you later if it worked and what exactly was wrong.

[Amel NASRI · Accepted solution]

Hi @Mathias Müller​ ,

Please check the order of the calls for HAL_ADC_Init() and HAL_DMA_Init().

In the generated code, make sure that HAL_DMA_Init() is called first, then HAL_ADC_Init().

-Amel

[MMüll.5]

Hi @Amel NASRI​ 

Thank you for your help. That was what caused the Problem, the HAL_ADC_Init() was called first. 👍

Can you explain to me why the HAL_DMA_Init must be called first and why the Cube MX does not do it like it is supposed to be?

It also would be useful to know how I can generate code from Cube MX and force it to initialize the DMA first because every time I generate code I need to switch the MX_DMA_Init and the MX_ADC_Init in which the HAL functions are called.

Thank you in advance.

Mathias

[Amel NASRI]

Hi @Mathias Müller​ ,

The peripheral initialization (HAL_ADC_Init() in your case) modifies a DMA register, which needs the DMA clock to be active. The clock is activated in the DMA initialization. That is why it is required to call HAL_DMA_Init then HAL_ADC_Init.

Unfortunately this was a regression introduced in STM32CubeMX 6.3.0. A fix is expected in next tool release.

A possible workaround is to force the order of functions calls. Please refer to the paragraph Ordering initialization function calls in the user manual UM1718 STM32CubeMX for STM32 configuration and initialization C code generation.

-Amel

PS: Once your question is answered, please select the relevant comment to be marked as a Best Answer.

[MMüll.5]

Thank you for all the information, know all is working as expected.