formula for Tmeas in i.MX7D

[ko-hey]

Hi all

I would like to measure the temperature of SoC using TEMPMON and have some questions.

Q1.

Please tell me the formula of Tmeans in i.MX7.

The calculation formula of Tmeas of p.4988 of i.MX7 RM Rev.1 is as below

On the other hand, the calculation formula of Linux source code is different.

Please see a line 585.

http://git.freescale.com/git/cgit.cgi/imx/linux-imx.git/tree/drivers/thermal/imx_thermal.c?h=imx_4.9...

Which one is correct ?

If the Linux code is correct, please tell me the formula for calculating the temperature at i.MX7 like "Tmeans = ???”.

Q2.

It seems to obtain the temperature using the calibration value in OCOTP_ANA1, but is OCOTP_ANA1 written at shipment?

Do we need to write the temperature by user ?

Ko-hey

[Yuri · Accepted solution]

Hello,

  Two points approximation in the RM  looks more accurate, nevertheless,

in practice one point approach provides reasonable results. Therefore our GA

Linux driver formula remains valid

Tmeas = ( Nmeas - n1) + 25; n1 is the fuse value for 25C (factory provided);

no changes to driver is needed.

Have a great day,
Yuri

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[ko-hey]

Hi Yuri Muhin

Thank you for quick reply.

How about Q2 ?

Ko-hey

[Yuri]

Hello,

  As has been mentioned, the fuse value is factory provided.

Regards,

Yuri.