malfunction diagnosis of ADC in 9S12XDP512

[jtpark]

Hello.

Would you let me know how to check malfunction of ADC in 9S12XDP512?

Thanks.

[RadekS]

Hi J.T.,

What about measuring some known voltage?

Unfortunately, S12XD do not provide the internal channel with bandgap reference voltage.

Could you please clarify your question? I am not sure whether…

1. do You want to implement some code which periodically checks ADC if it works correctly?
2. ADC in your S12XD MCU provide “wrong” results and you want test ADC whether an issue is in ADC itself or in the source of signal?

I hope it helps you.

Have a great day,
RadekS

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[jtpark]

Thanks for your reply.

No.2 is more closed to my concern.

Thanks.

[RadekS]

Hi J.T.,

Ok, the typical issue is the input impedance despite on fact that ATD at S12XD has an input buffer.

Could you please share here schematic related to the specific input channel and VDDA/VSSA, VRH, VRL power supply circuits?

The results may be also influenced by injection current into neighborhood channels. Please check that point.

Could you please share here you code for ATD? That we could check it for any obvious or potential issues?

More details about ATD module could be found in our application note AN2429 Interfacing to the HCS12 ATD Module

http://www.nxp.com/files/microcontrollers/doc/app_note/AN2429.pdf

I hope it helps you.

Have a great day,
RadekS

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