Temperature monitor of IMX6UL doesn't work as expected

[ethanyang]

We now have the use of i.MX6UL on our products.

According to the Security Reference Manual, low-temperature monitor should assert between -40 and -20 degree.

However we found that some units will start to have the temperature tamper event at -16 degree C.

We've tried the TEMP_LOW_OFFSET bits of DryIce Tamper Offset Control Register (SNVS Expanded_DTOCR), but it makes no different.

And there's another issue about the temperature shown by u-boot.

The CPU temperature is abnormal when the unit is placed in a chamber with temperature below 0 C.

Not sure if the behavior of temperature monitor is related to the wrong temperature.

But it'll be helpful if there is a fix for this.

Thanks.

Ethan

[registry_chou]

Hi Yuri,

Our engineering team has a question for this, but Ethan has leave for a long time.

Could you provide the patch for us? And we need try to reach -35 C.

Regards,

Jeff

[Yuri]

registry.chou@gmail.com 

Hello,

  Please create separate request or thread

Support | NXP 

Regards,

Yuri.

[registry_chou]

Okay.

[ethanyang]

Hi Yuri,

Thanks for the information.

Any chance that we can lower the asserting range by configuring some register?

And what about the wrong temperature display in u-boot? Do you know if there is a fix for it?

Regards,

Ethan

[Yuri]

Hello,

1.

   I sent You some comments regarding the temperature monitor directly via e-mail.

2.

  On my i.MX6 UL EVK :

U-Boot 2016.03-imx_v2016.03_4.1.15_2.0.0_ga+g0ec2a01 (Sep 16 2016 - 18:27:03 -0500)

CPU: Freescale i.MX6UL rev1.0 528 MHz (running at 396 MHz)
CPU: Industrial temperature grade (-40C to 105C) at 36C
Reset cause: POR
Board: MX6UL 14x14 EVK
I2C: ready
DRAM: 512 MiB
MMC: FSL_SDHC: 0, FSL_SDHC: 1
Card did not respond to voltage select!
*** Warning - MMC init failed, using default environment

Display: TFT43AB (480x272)
Video: 480x272x24
In: serial
Out: serial
Err: serial
MMC: no card present
Net: FEC1
Normal Boot
Hit any key to stop autoboot: 0
=>

Regards,

Yuri.

[ethanyang]

Hi Yuri,

1. Sorry I didn't mentioned that, but we're already using the trim value.

2. The issue we found is that u-boot shows wrong a negative temperature. No problem in showing a positive temerature.

Regards,

Ethan

[Yuri · Accepted solution]

Hello,

 The BSP does not support negative temperature value.

I've sent patch to try via e-mail.

Regards,

Yuri.

[sunzhg20]

Can you provide me with the patch pack?

[Yuri]

@sunzhg20 

Hello,

   Please create new request / thread regarding the issue.

https://www.nxp.com/support/support:SUPPORTHOME?tid=sbmenu

Regards,
Yuri.

[sunzhg20]

我也遇到这个问题 IMX6ULL 温度出现负数

这个如何打补丁？谢谢！

[ethanyang]

Hi Yuri,

The patch works. Thanks a lot.

Regards,

Ethan

[Yuri]

Hello,

  have You tried to check general system operation under the low temperature, using,

say, DDR stress test ?

i.MX6/7 DDR Stress Test Tool V2.60 

Have a great day,

Yuri

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[Yuri]

Hello

  Accuracy of the temperature sensor is not very high (+/-5 degree) .

Also, please look at app note AN5215 (i.MX 6 Temperature Sensor Module)

http://www.nxp.com/assets/documents/data/en/application-notes/AN5215.pdf 

Have a great day,
Yuri

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