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I'm planning to use an ATSAMC21G16 in one of my current projects. But I got a hard time finding the correct pin in the Datasheet for the SDADC.

On page 907 the block diagram shows, that VREFB can be selected as a reference for the SDADC. Page 907 On page 920 this is confirmed by the bit for reference selection. Also here VREFB is clearly mentioned Page 920 However, this pin is nowhere to be found in the port function multiplexing table on page 30 for the ATSAMC21G version. enter image description here

I can only find it in the table for the ATSAMC21N model.

Does this mean, that only for the N package version an external reference can be selected for the SDADC? Or is there something I'm missing? If it is not available, why would they design it that way? Because with the internal reference stability and accuracy, the 16bit resolution seems to be pointless to me.

KarlKarlsom
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I just checked the SAM C 20/21 datasheet on microchip's product page for the ATSAMC21.

Maybe you have a different version of the datasheet, because in table 6-2 on page 30, it shows SDADC/VREFB on PA04 for the C21 E/G/J - peripheral function B. It's possible they forgot to include it, and then added it later after you had looked.

SAM C20 Table 6-2

Kurt E. Clothier
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