topic S32K322 Adc_SelfTest - Cpu Temperature in S32K

S32K322 Adc_SelfTest - Cpu Temperature

Marekp — Thu, 29 May 2025 12:14:43 GMT

Hello, I'm encountering an issue with the ADC self-test and CPU temperature measurement.

After executing Adc_SelfTest(0) and Adc_SelfTest(1), the ADC1[ch17] channel starts returning incorrect values, which seem to be random and inconsistent.

Marekp_2-1748520826068.png

ADC readings Self test - NXP Community

Marekp_0-1748520410813.png

ADC instances 0 and 1 are triggered via BCTU. According to the documentation, BCTU triggering is disabled during the self-test. The self-test is executed, and the registers IP_ADC_0->MCR, IP_ADC_1->MCR, and IP_BCTU->MCR are restored to their original values afterward.

However, despite restoring the configuration, ADC1[ch17] continues to return random samples after the self-test is completed.

Marekp_1-1748520794936.png

What additional steps should be taken after the self-test to ensure the CPU temperature measurement is correct?

Re: S32K322 Adc_SelfTest - Cpu Temperature

_Leo_ — Wed, 04 Jun 2025 21:25:05 GMT

Thank you for your interest in our products and for contributing to our community.

Could you please replicate the issue using one of our evaluation boards and share the project with us? This will help us investigate the problem thoroughly and provide you with an accurate solution.

Re: S32K322 Adc_SelfTest - Cpu Temperature

Marekp — Thu, 05 Jun 2025 06:05:07 GMT

Hi, I don’t have the evaluation board, but I’m using this processor in my project. I’ve attached some screenshots from the Tresos configuration.

Marekp_0-1749103381925.pngMarekp_1-1749103390868.png

Marekp_2-1749103408852.pngMarekp_3-1749103439767.pngMarekp_4-1749103453990.pngMarekp_5-1749103467281.pngMarekp_6-1749103492987.png

Re: S32K322 Adc_SelfTest - Cpu Temperature

_Leo_ — Mon, 16 Jun 2025 19:44:52 GMT

Thanks for your patience. ADC self-test can't execute in BCTU mode. As is stated in reference manual: "Self-test conversion in BCTU mode is not supported in S32K3xx devices". Sorry for the inconvenient.

Re: S32K322 Adc_SelfTest - Cpu Temperature

Marekp — Tue, 17 Jun 2025 05:11:24 GMT

Hello, I’m aware of this, and as I mentioned in the previous message, the BCTU is disabled before starting the ADC self-test.
After the ADC self-test, the BCTU is enabled again.
However, my question is: why does Channel 49 – CPU Temperature – provide incorrect measurements after these steps?

Re: S32K322 Adc_SelfTest - Cpu Temperature

_Leo_ — Fri, 20 Jun 2025 20:01:41 GMT

Please provide your project in a new community post to debug it in one of our EVB. This in order to get the full picture and be able to provide an accurate response.