FXTH871511 Temp compensated pressure reporting

[mandar_gadgil]

We are using FXTH871511DT1 for our Tyre pressure monitoring system & would like to know if there is a method for temprature compensation of pressure inside the sensor. We can see reported pressure ( Pcodes) increasing with increase in ambient temperature & vice versa. Since the sensor has a temp sensor internal to it & it measures absolute pressure does it also have a mechanism for reporting temperature compensated pressure

[TomasVaverka]

Hi Mandar,

Measuring the actual value of pressure is done in two steps:

1. TPMS_READ_PRESSURE(gu16UUMA, 1u) stores the 10-bit uncompensated value of pressure (output of the ADC) in UUMA.

2. TPMS_COMP_PRESSURE(&u16CompPress,gu16UUMA) performs a compensation of the pressure value stored in UUMA: the function linearizes the value and correct the error due to temperature and voltage.

So there should be no need for an additional temperature compensation.

Best regards,

Tomas

[mandar_gadgil]

Hello Tomas,
Thanks for the inputs. We are using the compensated pressure for calculations in the FW. When we install the TPMS in a tyre & the temp of the tyre increases the temp values reported by the chip increases & the pressure reported increases along with the temperature. I know that the air pressure increases with the increase in temp , is this behaviour attribute to this phenomenon. I was under impression that the this variation is compensated in the chip. Can you please explain what is expected behaviour of the chip in such condition.

Regards,
Mandar