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Yes, so most pins on Espruino (apart from ADC pins) are 5v tolerant and pulling up to 5v is fine. Personally I use 4k7 pullups to 3.3v, so it may be that just having a 3.3v pullup with a higher resistance would be fine for you?
Having said that I've only tried maybe 5 different I2C devices, so some of them may require that 5v pullup.
Hi
I've been attaching my Espruino board to my existing I2C busses which have previously been tested with Arduino and other devices.
One interesting question is bus voltage: the I2C devices I'm using are on PCBs that require a 5V power supply. In the past, I've connected up a 3.3v Arduino - I just used pullups to 3.3v instead of 5v, and this worked. But it didn't work work with Espruino.
Then I realized that the Espruino pins used for I2C are 5V tolerant, so I've changed the pullup to connect to 5v - and it seems to work now :)
However, I am using 2k7 pullups, which I suspect may be a bit too low. I think the general advice is 4k7 to 10k?
Thoughts?