Trying to make sense of SAML21 datasheet

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It says "When an analog peripheral is enabled, the analog output of the peripheral will interfere with the alternative functions of this pin. This is also true even when the peripheral is used for internal purposes." And I have absolutely no idea what they mean.

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Just a guess to make up an example: if you use the DAC1 output as input to OPAMP1 (not intending to output VOUT1 on PA05, i.e., internal use only) you can still not expect to use the alternate functions of PA05, e.g., you can't have  SERCOM0/PAD[1] on PA05.

/Lars

 

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But DAC and SERCOM are different functions (B and D). How can I possibly select both of them at the same time? Or any other combination of alternative functions? Perhaps they mean the B functions? Like you cannot use PA05 as an AC1 input if you also enabled the DAC1 output? They don't have any notes like that in the SAMD datasheet...

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I understand this like this:

The analog functionalitity with its connection and use of the voltage reference of the "analog pins" does interfere with this voltage.

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I guess the analog output is not isolated by the multiplexer.  So if enabled in peripheral control but the alt function of the pin is assigned to something else there can be interference.

 

I feel your pain with SAMD data sheets.   I have that "WTF are they talking about"  experience frequently.

 

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ezharkov wrote:
But DAC and SERCOM are different functions (B and D). How can I possibly select both of them at the same time?
The OPAMP can use the DAC output without it being muxed to a pin, this is "the peripheral is used for internal purposes".

/Lars