Re: Raduino logic levels


I2C is not a "normal" port. (good for us) ;-)

Two quotes from forum:

"I see, so that's what "When the TWEN is set to enable the Two-wire Serial Interface, pin PC1 is disconnected from the port" meant on the datasheet."


"Both pins (SDA, SLC) are bidirectional, so both must be configured always as output. They are used from the HW-I2C as open drain outputs, thus also two external pullups are needed."

The key is "open drain" (like open collector). ". Both SCL and SDA lines are "open drain" drivers. What this means is that the chip can drive its output low, but it cannot drive it high."


Best 73



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