i.MX 8M Mini TMU temperature readout problem

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i.MX 8M Mini TMU temperature readout problem

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ralfgoebel
Contributor III

Hello,

We have a new custom hardware using the i.MX 8M Mini SoC (commercial grade).

The temperature values reported by the TMU seem to be incorrect. At case temperatures of about 20°C ... 35 °C, I see the following values reported by U-Boot: 16°C, 18°C, 24°C, 28°C, 32°C, 36°C, 64°C, 72°C, 112°C.

Above 35°C, the temperature reading fails.

The same problem occurs within Linux.

Is there some temperature calibration required for the TMU?

Thanks,

Ralf

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b36401
NXP TechSupport
NXP TechSupport

The calibration values are in the efuses at:
0x4F0[7:0] TSENSOR_VALUE_RT[7:0] (room temp)
0x4F0[15:8] TSENSOR_VALUE_HT[7:0] (high temp)

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ralfgoebel
Contributor III

The efuse values for our boards are within the following ranges:

TSENSOR_VALUE_RT: 0x34 ... 0x39
TSENSOR_VALUE_HT: 0x69 ... 0x6f

Are they reasonable?

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