I realised there was such a problem, when I was trying to convert ADC temperature sensor data to degrees in Celsius. After many hours of trying to find a formula that works I found this one from the repository examples:
ADCxConvertedData_Temperature = (((ADC_Data - 0.76)/(TS_CAL2 - TS_CAL1)) + 25);
So far so good, but when I run the code I get values around 27 - 28 degrees, which is not impossible, but seems too high for it to be room temperature, so I wrote another formula which seems to be also accurate for temperature conversion:
temp = (uADC_DR_val[6] / ((TS_CAL2 / 110 + TS_CAL1 /30)/2));
But with this one I also get values from 26 to 28 degrees.
So I decided to try and calculate these formulas with pen and paper using the ADC value that the MCU got and it turns out, I got lower numbers as a result. For example, using the first formula, where ADC_Data = 585, according to my calculations I get a result of 25.27 degrees, but my code calculates the same formula as 27.204.
I also saw that even when I use int variables I don't always get the number rounded correctly. Sometimes it rounds 26.3 to 27 and sometimes it rounds 27.7 to 27.
My question is, is it possible, that I don't have the FPU set up correctly (I checked and the FPU is enabled both in the MCU settings and in the CubeMX FreeRTOS settings) or could there be a problem with the hardware and that's why it is acting so weird?
I am using a custom board with STM32F407 MPU.
PS. I also get a HardFault when trying to do three or more floating point operations, which reads to be Bad Address Read.
