5 volts on Qwiic SCL and SDA

[david-i]

On the schematics, the Qwiic connector pins have GND and 3.3V,
but SCL and SDA come directly from the SCL/A5 and SDA/A4 pins of the Arduino.
This means they are operating at a 5 volt logic level instead of at 3.3 volt.

Doesn't this create a problem when connecting to Qwiic boards that have 3.3 volt
logic and pull-ups?

(The 4-port Qwiic shield does have circuitry to convert between 5v and 3.3v for the bus)

[nseidle]

You are correct in that when the shield is connected to a 5V Arduino, anything attached to that Qwiic connector would be powered by 3.3V and may be exposed to 5V SDA/SCL signals. I say 'may be' because ideally the I2C bus is open drain so it depends on which rail the pull ups on the bus are attached to.

All that said, I should have put translation on there to be safe, but I my head has been in 3.3V for so long I forgot. I'll leave this open as reminder/warning for others.