The Blue Pill: 5V tolerant vs 3.3V standard pins

Working libraries, libraries being ported and related hardware
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Llama
Posts: 12
Joined: Sun Oct 22, 2023 4:35 pm

The Blue Pill: 5V tolerant vs 3.3V standard pins

Post by Llama »

Hi,

Formally, the difference is clear enough. Well, off the record: are those 3.3V pins equally intolerant of any use with 5V in the circuit? I suspect, for instance, that the usual LED + resistor arrangement won't kill the 3.3V pin even if the pull-up is connected th 5V. Is it really so?
ag123
Posts: 1653
Joined: Thu Dec 19, 2019 5:30 am
Answers: 24

Re: The Blue Pill: 5V tolerant vs 3.3V standard pins

Post by ag123 »

Accordingly, tolerant pins have diodes that sink currents, but they still require a high enough resistor to limit the currents going into the pin.
For non-tolerant pins you are taking your chances
http://www.emcu.eu/000/STM32_5VtolerantIO.pdf
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