MPC5xxxのトピックRe: TSENS Measurements Issue

TSENS Measurements Issue

ahmedsoubky — Tue, 20 Dec 2016 16:34:33 GMT

Hello,

We are using MPC5744p microcontroller.

We have requirement which states that "During power up, the two temperature sensors are to be read by
software (TSENS0 from ADC0 channel 15, TSENS1 from ADC1 channel 15). The
software must verify that the conversion values are similar, as this is a means of assessing
that the sensors are working properly."

The sequence described in the example code here along with the reference manual formula has been followed.

However, the temperatures read from the sensors aren't exactly the same. There is a difference of 2°C on my board and around 8°C on my colleagues board.

Any explanation what is the reason of this and how can we overcome it ?

Thanks in advance,
Best Regards,
Ahmed

Re: TSENS Measurements Issue

davidtosenovjan — Thu, 22 Dec 2016 13:19:06 GMT

These sensors have accuracy stated as +/-3% thus it could be in tolerance. You are measuring it on different boards thus environment probably is not completely equal (ambient temperature, voltage reference and so on).

Re: TSENS Measurements Issue

davidtosenovjan — Thu, 22 Dec 2016 13:24:04 GMT

Sorry I have understood it wrong way. You see difference between TSENS0 and TSENS1, always on the same device, right?

Could I see your code snippet (I am only interested in ADC and TSENS code portion). Have you tried to increase sampling time?

Re: TSENS Measurements Issue

davidtosenovjan — Fri, 23 Dec 2016 12:34:29 GMT

One yet note - my collegue shared example code for this device:

https://community.nxp.com/docs/DOC-104657

Have you seen it?