CPU die temperature detect wrong

[jane-jiajuan_zh]

Hi,

One of my board(imx6 solo) detect the cpu die temperature wrong, below is some key logs:

U-Boot 2018.03 (Oct 17 2019 - 10:39:25 +0800), Build: jenkins

CPU: Freescale i.MX6SOLO rev1.3 at 792MHz
CPU: Industrial temperature grade (-40C to 105C) at 98C
Reset cause: POR
Model: Freescale i.MX6 DualLite SABRE Smart Device Board
Board: MX6-SabreSD
DRAM: 1 GiB

in kernel log:

[   69.283725] thermal thermal_zone0: critical temperature reached (101 C), shutting down

[ 74.483731] thermal thermal_zone0: critical temperature reached (101 C), shutting down
[ 75.523704] thermal thermal_zone0: critical temperature reached (102 C), shutting down

I would like to know if the OCOTP affect the temperature detection?

And the board is abnoraml now, it cannot boot up without USB.

I suspect the problem is more like the hardware on this board work abnoraml. But I want to double check is the OCOTP value will affect the temperature?

Thanks in advance.

Jane

[jming]

Hi Jane,

My IMX8M custom board has the similar issue, Have you fixed the issue?

Thanks.

[igorpadykov]

Hi Jane

one can check temperature calibration app note

i.MX 6 Temperature Sensor Module - Application Note

Calibration coefficients are stored in fuses.

Also one can try with different samples and if issue occurs only with specific batch

work with local marketing office for FA procedure.

Best regards
igor
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[jane-jiajuan_zh]

Hi igor,

Does the 0x4E0[31:0] (Analog_temp_sense[31:0]) had been calibrated before the chip shipped?

Is there any possible to make the temperature wrong when writing fuse wrong?

This abnormal chip was working well before, After fused it detects the temperature wrong. But I am not sure the root cause is fusing wrong or physical damaged.

BR,

Jane

[igorpadykov]

Hi Jane

yes chips are calibrated before shipped.

In general wrong fusing may cause above malfunction.

Best regards
igor

[jane-jiajuan_zh]

Hi  igorpadykov,

Thank you for your replying,  does the 0x4E0[31:0] (Analog_temp_sense[31:0]) have a range?  How could I know the value in our board is right?

BR,

Jane

[igorpadykov]

Hi Jane

>How could I know the value in our board is right?

sorry there is no way to know. Only running nxp software described on

i.MX Software | NXP 

Best regards
igor

[jane-jiajuan_zh]

Hi igorpadykov,

one of my chipset detect temperature wrong, the log in uboot is "CPU: Industrial temperature grade (-40C to 105C) at 98C", but use the thermal imager to ensure it only 40C now.

So I would like to know if it caused by wrong value of  0x4E0[31:0] (Analog_temp_sense[31:0]).

Is there any way to find the root cause?

BR,

Jane

[igorpadykov]

Hi Jane

>Is there any way to find the root cause?

no direct way, sorry.

You can resolder chip (assuming poor soldering).

Change to another part (assuming part is broken).

Best regards
igor