GPIO logic thresholds

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JoBr_1593366
Level 5
Level 5
100 sign-ins 50 questions asked 100 replies posted

PSoC 3 Pins component has a Vref option:

pastedImage_2.png

This then requires an external Vref, which can be set to 0.256 V:

pastedImage_1.png

But the datasheet doesn't seem to list the "Input voltage low threshold" for this configuration?  What are the margins of error on this threshold?

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1 Solution

Hi,

"If I want a more accurate threshold without so much variability, should I use a comparator?"

Yes for measuring voltage more than 0.256 you can use a comparator.

Please refer the below table for max Vinref value

pastedImage_1.png

Regards

Alakananda

Alakananda

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Alakananda_BG
Moderator
Moderator
Moderator
50 likes received 250 sign-ins 250 replies posted

Hi,

Can you please refer to VIL in the below table.

pastedImage_1.png

Regards

Alakananda

Alakananda
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Ok, but which one applies to the Vref setting?  Is that considered "differential mode"?  So the threshold would actually have a range of 0.256±0.2 V?  What if Vref*0.5 is selected?  The threshold would then be 0.128±0.2, which would drop below 0 V and not work?

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If I want a more accurate threshold without so much variability, should I use a comparator?

pastedImage_0.png

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Hi,

"If I want a more accurate threshold without so much variability, should I use a comparator?"

Yes for measuring voltage more than 0.256 you can use a comparator.

Please refer the below table for max Vinref value

pastedImage_1.png

Regards

Alakananda

Alakananda
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Which document is that from?

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Hi,

It is from PSoC® 3: CY8C38 Family Datasheet.

Pg no 82 section 11.4.2

Regards

Alakananda

Alakananda
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