topic Re: Determining ASIL-level of populated SBC via microcontroller in Power Management

Determining ASIL-level of populated SBC via microcontroller

Joey_van_Hummel — Fri, 16 Jul 2021 14:50:53 GMT

Hi,

We are designing a product using the MC33FS4500 series SBC. These SBC's are available in both ASIL-B and ASIL-D level, most notably the ASIL-B variant does not require the LFSR calculation for WD_ANSWER. We require ASIL-D for our application.

The ASIL-B and ASIL-D parts are pin-compatible and I was wondering: if an ASIL-B part was accidentally populated instead of an ASIL-D part, could software reliably detect this? DEVICE_ID_FS and DEVICE_ID seem unusable for this goal. Maybe DEV_REV is usable, but this field is not documented in detail.

Of course, we can refresh the watchdog with an erroneous WD_ANSWER write and see how the error counter responds, but I'd like to have a more robust solution.

Kind regards,

Joey

Re: Determining ASIL-level of populated SBC via microcontroller

TomasVaverka — Mon, 19 Jul 2021 13:15:12 GMT

Hi Joey,

Yes, DEV_REV bits can be used to distinguish between ASIL-B and ASIL-D parts.

For ASIL-D, DEV_REV = 010;
For ASIL-B, DEV_REV = 111;

Usually, their actual values are mentioned in the ‘Revision History’ subsection of the datasheet, but we missed to implement it in the ASIL-B datasheet.

Best regards,

Tomas

Re: Determining ASIL-level of populated SBC via microcontroller

Joey_van_Hummel — Mon, 19 Jul 2021 13:34:34 GMT

Hi Tomas,

Thank you. This is exactly what I was looking for.

Kind regards,

Joey