In 'L431, is ADC channel 6 fast for single-ended conversions?

[waclawek.jan]

Where do the "Fast channel" and "Slow channel" texts belong to? To *pins*, or to *inputs to ADC*? If former, why are they not unambiguously on the left hand side of picture, next to the pins names? If latter, why are they only on every other input to ADC?

The highlighed line appears to be closer to "Slow channel" below it, but the 'L431 DS says PA1 is fast. I suspect, ADC6 is fast as long as it's used as single-ended and slow when used as differential (as that then involves PA2 which is slow), but why can't this figure or some text say this out explicitly and clearly?

JW

[KDJEM.1]

Hello @Community member​,

The note in the STM32L431 datasheet (DS11453) is wrong.

PA1 shouldn’t be marked as a Fast channel.

Thanks for reporting the issue.

I reported internally.

Internal ticket number: 137928 (This is an internal tracking number and is not accessible or usable by customers).

Kaouthar

[waclawek.jan]

Hi Kaouthar,

Thanks for the explanation.

Regardless of PA1, I still believe Fig41 can/should be made less ambiguous, as per my previous comment:

Where do the "Fast channel" and "Slow channel" texts belong to? To *pins*, or to *inputs to ADC*? If former, why are they not unambiguously on the left hand side of picture, next to the pins names? If latter, why are they only on every other input to ADC?

Jan

@KDJEM.1​ 

[KDJEM.1]

Hello @Community member​,

Fast and slow channels refer to ADC channels, and not to pins.

The channel type is written between the positive and negative inputs.

For example, below VINP[5] and above VINN[5], which means channel 5 is Fast.

Thank you.

Kaouthar

[waclawek.jan]

Hi Kaouthar,

thank you for your explanation.

> The channel type is written between the positive and negative inputs.

Then caption to the Figure should say that explicitly, as this is not self-evident.

IMO it's simpler to write it above all lines. Alternatively, it might be better to spatially separate the signal pairs in the picture.

Also, in light of this explanation, your previous answer

> PA1 shouldn’t be marked as a Fast channel.

is not true either, and the whole footnote in datasheet ought to be rephrased to reflect the truth.

JW

[KDJEM.1]

Hello @Community member​,

Yes, I confirm this issue and I think that it is useful to modify the footnote in the datasheet "Fast channels are: PC0, PC1, PC2, PC3, PA0." by "Fast channels are available by access pins: PC0, PC1, PC2, PC3, PA0."

Thank you.

Kaouthar

[waclawek.jan]

Thanks, Kaouthar.

Jan