when 0.000030517578125 multiplied with any number getting result as Zero

[Saagar]

Hi

I am reading the sensor data (Irms and Vrms) via I2C protocol and multiplying the read data with 0.000030517578125 to get correct result but i am getting the result as zero

Vrms = ((m_sample[1] << 8) | m_sample[0]);
Irms = ((m_sample[3] << 8) | m_sample[2]);

float Vrms_acc = ((float)Vrms) * (0.000030517578125);
float Irms_acc = ((float)Irms) * (0.00006103515625);


NRF_LOG_INFO("-------------------\r\n");
NRF_LOG_INFO(" Recevied Data.\r\n");
NRF_LOG_INFO(" Vrms = " NRF_LOG_FLOAT_MARKER "\r\n", NRF_LOG_FLOAT(Vrms_acc));
NRF_LOG_INFO(" Irms = " NRF_LOG_FLOAT_MARKER "\r\n", NRF_LOG_FLOAT(Irms_acc));
NRF_LOG_INFO("-------------------\r\n");

---------------------------------------------------------------------------------------------------------------------------

OUTPUT

ENERGY_METER:INFO:-------------------
ENERGY_METER:INFO: Recevied Data.
ENERGY_METER:INFO: Vrms = 0.000000000000000
ENERGY_METER:INFO: Irms = 0.000000000000000
ENERGY_METER:INFO:-------------------

Thanks in advance 

[Saagar]

CheMax Thank you  now i am able to get the correct values.
Turbo J Thank you for the information

[CheMax]

You're welcome.

For segger, there is another solution that, in principle, works correctly.
1. In the settings (project options -> code -> Printf/Scanf),  set the permission to output numbers with double precision through the printf function: 

Printf Floating Point Supported = double

Wide Characters Supported = Yes

Note: be prepared for a slight increase in the consumption of flash and RAM memory.

2. add header file: #include <debugio.h>

3. use one of the following output:

debug_printf("test: %.9f \n", 100.123456789);

[Saagar]

Thank you 

Another problem i am facing is when i multiply Vrms and Irms with overall full scale of voltage path (i.e 230v) And

overall full scale of current path (i.e 90 A) respectively i am getting worng result.

float Vrms_acc = ((float)Vrms) * ((0.00003051757) * 230);
float Irms_acc = ((float)Irms) * ((0.00006103515) * 90);

result:

Vrms = 0.-02088566784
Irms = 0.-00202559488

 i am not getting why that - sign is coming.

Thanks in advance

[CheMax]

There are not enough sample values to verify.
I can assume that there is either not enough accuracy float and you need to switch to double.

I try this code:

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <debugio.h>

/*********************************************************************
*
*       main()
*
*  Function description
*   Application entry point.
*/
int main(void) 
{
  uint32_t Vrms = 10;
  uint32_t Irms = 10;

  double Vrms_acc = ((double)Vrms) * ((0.00003051757f) * 230.0f);
  double Irms_acc = ((double)Irms) * ((0.00006103515f) * 90.0f);

  debug_printf("Vrms : %.9f \n", Vrms_acc);
  debug_printf("Irms : %.9f \n", Irms_acc);
  

  for(;;)
  {
  }
}

/*************************** End of file ****************************/

And this:

int main(void) 
{
  uint32_t Vrms = 10;
  uint32_t Irms = 10;

  float Vrms_acc = ((float)Vrms) * ((0.00003051757) * 230);
  float Irms_acc = ((float)Irms) * ((0.00006103515) * 90);

  debug_printf("Vrms : %.9f \n", Vrms_acc);
  debug_printf("Irms : %.9f \n", Irms_acc);
  

  for(;;)
  {
  }
}

the result is the same: