Higher precision in BLE_UUID_HEALTH_THERMOMETER_SERVICE

[bimcio]

Hi,

I am trying to include temperature (read from DS18B20) in advertisement data using BLE_UUID_HEALTH_THERMOMETER_SERVICE. So far it works fine, but my temperature is multiplied by 10 (234 instead of 23.4). I use following code (inspired by examples I found), on nrf51822:

  uint32_t temperature_data = measure_temp_ds18b20();

  service_data[1].service_uuid = BLE_UUID_HEALTH_THERMOMETER_SERVICE;
  service_data[1].data.size    = sizeof(temperature_data);
  service_data[1].data.p_data  = (uint8_t *) &temperature_data;

Temperature is shown correctly (e.g. in nRF Temp app on android) but of course as 234, instead of 23.4. Is it possible to send this value as fractional?

greetings, Bartek

[Michael Dietz]

What type does measure_temp_ds18b20() return? If you are expecting a decimal i.e. 23.4 but you are storing it in uint32_t then thats a problem. Then looking at the code you provided you are storing the uint32_t into p_data in an array of uint8_t. So if you want a decimal reading maybe you need to read your measure_temp..() into a float or double or something and then store it to p_data as that type (if thats possible im not really sure). Otherwise maybe you keep it as sending in a uint32_t and just know how to interpret those raw bits on the other side of the BLE link.