CC2541 Temperature sensor Calibration

Mateusz Romanowski

Other Parts Discussed in Thread: CC2541, CC2540

Hi!

I'm looking for information about internal temperature sensor calibration value stored in the Information Page of XDATA Register in CC2541.

In the CC2541 User Guide we can only read that Information Page that "stores various device information", i.e. the IEEE address.

In this thread (CC2540) http://e2e.ti.com/support/wireless_connectivity/f/538/p/256580/916756#916756 it seems that there is some calibration value stored in Information Page, at specific addres.

Code fragment from the thread:

" uint16 adcTemp25= *((uint8 *)INFOPAGE_WORD7 + 2) << 6 | *((uint8 *)INFOPAGE_WORD7 + 3) >> 2;

(...)

I got the values below.

(...)

adcTemp25 = 5793

Is this similar in case of CC2541? If so, what is the XDATA address of this value?

The calibration value I expect is internal temperature sensor ADC readings at 25 °C. The datasheet gives typical value of 1480, but different units have different offset.

We tested 6 of CC2541 units and there were temperature differences up to 10 °C between them. All units indicated temperature up to 15 ° lower than real ambient temperature.

So, is there temperature sensor readings at 25°C stored in Information Page for CC2541?

Thanks in advance for any hints

Regards,

Mateusz

over 9 years ago

0 Mateusz Romanowski over 9 years ago

Prodigy 40 points

Hi

Any help would be appreciated

Let me rephrase my question:

Is 1-point calibration of internal temperature sensor done during production of CC2541 chips?
Is the value stored in "Information Page" Flash section?

This will be used for an interesting case - a temperature dependent compensation of Tx Power.

Regards,

Mateusz

0 Fredrik K over 9 years ago in reply to Mateusz Romanowski

TI__Guru** 106705 points

Hi Mateusz,

We do test the internal temperature sensor in chip production and store the result in the info page (see figure below). The production environment is not accurately temperature controlled so there could be an absolute offset for a batch of devices.

Cheers,
Fredrik

0 Mateusz Romanowski over 9 years ago in reply to Fredrik K

Prodigy 40 points

Fredrik K said:

Hi Mateusz,

We do test the internal temperature sensor in chip production and store the result in the info page (see figure below).

Thank you for your reply! I understand that you wanted to post something below (specific info page addresses perhaps?) but it didn't show up in a post. Could you post it once again?

Regards,

Mateusz

0 Fredrik K over 9 years ago in reply to Mateusz Romanowski

TI__Guru** 106705 points

Hi Mateusz,

Seems like my picture was deleted. Let me try again.

BR,
Fredrik

0 Mateusz Romanowski over 9 years ago in reply to Fredrik K

Prodigy 40 points

Thank you!

I'm trying to understand why there are different Vdd for these test? Vdd = 2 V with 123 grads celsius and Vdd = 3 V with 23 grads?

0 Fredrik K over 9 years ago in reply to Mateusz Romanowski

TI__Guru** 106705 points

Hi Mateusz,

I think I cut partly the wrong part. The HT test is not included anymore, you will only have access to measurements at room temp for 2 V and 3 V.

I will update the post tomorrow.

0 Fredrik K over 9 years ago in reply to Fredrik K

TI__Guru** 106705 points

Hi Mateusz,

I have included the correct data now. Keep in mind that these measurements are not done in a temperature controlled environment (even though the description says 23 degC).

Cheers,
Fredrik

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CC2541 Temperature sensor Calibration