Voltage Sense with multichannel ADC DMA

[YalnizKurt]

Hello everyone,

I have designed my own card and used F103 uC on it. I want to measure battery voltage with DMA method. I hope to drive BLDC motor with this card one day So i need to measure phase voltages and BUS battery voltage. Due to speed issues, i thought DMA would be much better option. 

So, forget about the phase voltages first. I just want to sense battey voltage.  I have defined some variables. I have voltage driver on the same line so i need to multiply every array value with multiplier. I eant to write buffer values to data array for true measurement of the voltage. Then i want to send this scaled values to my computer.

#define Buffer_Size 5

uint16_t V_BATT_ADC_Buffer[Buffer_Size]={0};
uint16_t V_BATT_ADC_Data[Buffer_Size]={0};
float V_BATT_ADC = 0.0;
float V_BATT = 0.0;
uint8_t V_BATT_Sense_Conv_End = 0;
float multiplier_V_BATT = (3.3/4095)*(100+5.6)/5.6;

void multiplyArray(uint16_t *array, size_t size, float multiplier) // Array multiplication function
{
for (size_t i = 0; i < size; i++)
{
array[i] = (uint16_t)(array[i] * multiplier);

}
}

void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc) // Get value with DMA and write it when Conv. Cmp. to other array function
{
if (hadc == &hadc3)
{

for(int i = 0 ; i<Buffer_Size; i++)
{
V_BATT_ADC_Data[i] = V_BATT_ADC_Buffer[i];
}
V_BATT_Sense_Conv_End=1;
}
}

int main(void)

....

....

HAL_ADC_Start_DMA(&hadc3, (uint32_t *)V_BATT_ADC_Buffer, Buffer_Size);

while(1)
........

........

if(V_BATT_Sense_Conv_End == 1)
{

size_t size = sizeof(V_BATT_ADC_Buffer)/sizeof(V_BATT_ADC_Buffer[0]);
multiplyArray(V_BATT_ADC_Buffer, size, multiplier_V_BATT);

char str[80];
int V_BATT_txlength = sprintf(str, "ADC Value: %d, Battery Voltage Level: %dV\r\n", V_BATT_ADC_Data[0], V_BATT_ADC_Data[1]);
HAL_UART_Transmit(&huart1, (uint8_t*)str, V_BATT_txlength, 100);

HAL_Delay(500);
V_BATT_Sense_Conv_End=0;
}

}

As summary, i want to sense battery voltage with dma then write it to an array then multiply this array according to my voltage divider and send it to my computer. I know it is little long but any help would be appreciated. 

[Karl Yamashita]

Use the code sample button so your code is properly formatted for easy reading.

 

[YalnizKurt]

Thanks a lot

#define Buffer_Size 5


void V_Sense_BATT(void);
void multiplyArray(uint16_t *V_BATT_ADC_Buffer, size_t size, float multiplier);


ADC_HandleTypeDef hadc3;


uint16_t V_BATT_ADC_Buffer[Buffer_Size]={0};
uint16_t V_BATT_ADC_Data[Buffer_Size]={0};
float V_BATT_ADC = 0.0;
float V_BATT = 0.0;
uint8_t V_BATT_Sense_Conv_End = 0;
float multiplier_V_BATT = (3.3/4095)*(100+5.6)/5.6;

static void MX_DMA_Init(void);
static void MX_ADC3_Init(void);

void multiplyArray(uint16_t *array, size_t size, float multiplier)
{
    for (size_t i = 0; i < size; i++)
    {
        array[i] = (uint16_t)(array[i] * multiplier);
    }
}



void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc)
{
    if (hadc == &hadc3)
    {

    	for(int i = 0 ; i<Buffer_Size; i++)
    	{
    		V_BATT_ADC_Data[i] = V_BATT_ADC_Buffer[i];
    	}
    	V_BATT_Sense_Conv_End=1;
    }
}


int main(void)
{
  HAL_ADC_Start_DMA(&hadc3, (uint32_t *)V_BATT_ADC_Buffer, Buffer_Size);
     while (1)
     {
         if(V_BATT_Sense_Conv_End == 1)
         {

         	size_t size = sizeof(V_BATT_ADC_Buffer)/sizeof(V_BATT_ADC_Buffer[0]);
     		multiplyArray(V_BATT_ADC_Buffer, size, multiplier_V_BATT);

        	char str[80];
     	    int V_BATT_txlength = sprintf(str, "ADC Data 1: %d, ADC Data 2: %dV\r\n", V_BATT_ADC_Data[0], V_BATT_ADC_Data[1]);
     	    HAL_UART_Transmit(&huart1, (uint8_t*)str, V_BATT_txlength, 100);
     	    HAL_Delay(500);
     	    V_BATT_Sense_Conv_End=0;
         }

     }
}

[Karl Yamashita]

You seem to be transmitting the battery voltage correctly. So I guess i'm not understanding the issue? 

[YalnizKurt]

Problem is i can not see battery voltage readings on CubeIDE Console. For testing the serial connection between my card and computer, i have used some dummy code. Looks like everything is okey. Then i narrow my code down and commented everything until;

  HAL_ADC_Start_DMA(&hadc3, (uint32_t *)V_BATT_ADC_Buffer, Buffer_Size);

 It looks like when i start dma, conversion never completes and there is an infinite loop. Could this be the problem?

[LCE]

When using DMA, you should not use the ADC conversion complete, but rather the DMA complete flag / interrupt.

And yes - at least on F7 / H7 - once started with HAL_ADC_Start_DMA() it runs forever unless stopped actively.
I actually like that for power monitoring: ADC / DMA is running constantly in the background, but I only check every few 100 ms by simply checking the ADC DMA buffer. 

You showed only snippets of your main code, correct? Because there's no inits called...

[YalnizKurt]

Thanks for your reply.

---

@LCE wrote:

When using DMA, you should not use the ADC conversion complete, but rather the DMA complete flag / interrupt.

---

So you say i dont have to use;

void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc)

What should i use instead of that? Can you please elaborate

---

@LCE wrote:

And yes - at least on F7 / H7 - once started with HAL_ADC_Start_DMA() it runs forever unless stopped actively.
I actually like that for power monitoring: ADC / DMA is running constantly in the background, but I only check every few 100 ms by simply checking the ADC DMA buffer. 

---

Actually i was planning to check battery voltage every 1 seconds  but measure phase voltages like every commutation. So i have to use  conversion end flag for them.

---

@LCE wrote:

You showed only snippets of your main code, correct? Because there's no inits called...

---

Yes

[LCE]

> What should i use instead of that? Can you please elaborate

Good question...

I think you can also activate DMA complete interrupts and callbacks.

As I said, I don't use these, just check the buffer when needed.

[Karl Yamashita]

---

---

You're not showing enough code. Have no idea where you're calling HAL_ADC_Start_DMA from? What do you mean by infinite loop?

Attach your IOC file so we can see your settings. 

[YalnizKurt]

Hi, sorry for late response. When i start debugger mode, it constantly loops inside HAL library of DMA function. It takes readings but never skips to incomong line.


Again, thanks for your big interest.