issue in sending the float value in ble_nus_send

[ps_anu]

Hi...

i have done the program to read the temperature sensor, i want to get the temperature in float value . i can able to read the temperature in float but i can't able to pass the float value in ble_nus_send . nRF52832 used segger 15.2v

here i am attaching my code , please tell me how to resolve this 

static void sensor_event_handler(void* p_context)


{
  uint16_t length1;
  uint16_t threshold;  
 
    char str[80];
     ret_code_t err_code;
 
     

        nrf_delay_ms(5000);

       while (m_xfer_done == false);
{
         m_xfer_done = false;
                
		uint8_t reg[2] = {0x00U};
        err_code = nrf_drv_twi_tx(&m_twi,LM75B_ADDR, reg, sizeof(reg), true);
		APP_ERROR_CHECK(err_code);
		while (m_xfer_done == false);
		nrf_delay_ms(5);
		
	        m_xfer_done = false;
		ret_code_t err_code1 = nrf_drv_twi_rx(&m_twi,LM75B_ADDR, &m_sample, sizeof(m_sample));
		APP_ERROR_CHECK(err_code1);
              
                
                NRF_LOG_INFO("hello :%d", m_sample);

                    uint16_t tempVal = (m_sample[0] <<  8) | m_sample[1];
        float tempC = tempVal * (0.0390625)/10;
       
 
    threshold=50;


  if(tempC < threshold )
            {
           
             length1 = sprintf(str,"%s%d.%01d", tempC);
 ble_nus_data_send(&m_nus,str,sizeof(tempC), m_conn_handle);
NRF_LOG_INFO("temp:%s%d.%01d", NRF_LOG_FLOAT(tempC));
          

              
             

                            
  }
       }
       }
  

Thanks in advance 

[Jørgen Holmefjord]

Hi,

Could you explain exactly with the problem is? Are you not able to compile? Is the float value not showing correctly? Any other issue?

Did you try using sprintf with %f for the float parameter?

Best regards,
Jørgen

[Jørgen Holmefjord]

What do you get over BLE? Note that sizeof(tempC) will return the number of bytes required to store a float (size of the type), which is 4, it will not return the actual length of the string.

Try something like this:

length1 = sprintf(str,"%f", tempC);
ble_nus_data_send(&m_nus,str,length1, m_conn_handle);

You should also check the error code returned from ble_nus_data_send().

[ps_anu]

i didn't get any value over ble

[Jørgen Holmefjord]

If you do not get any value, there is most likely some other issue. Check if the ble_nus_data_send function returns NRF_SUCCESS or some other error code.

[awneil]

Jørgen Holmefjord said:

Note that sizeof(tempC) will return the number of bytes required to store a float (size of the type), which is 4, it will not return the actual length of the string

Yes - as also noted in the duplicate thread:

https://devzone.nordicsemi.com/f/nordic-q-a/48419/how-to-send-the-float-to-string-over-ble_nus/191946#191946

[ps_anu]

even i tried that also , by changing the length  . still i am not getting any value

[awneil]

ps_anu said:

i am not getting any value

Again:

Jørgen Holmefjord said:

If you do not get any value, there is most likely some other issue

Go back to the original, unmodified example and confirm that works.

As suggested in your duplicate thread, Have you checked that the string conversion is actually working?