3.3v to 5v logic Converter and voltage booster

I got a MKR1000 that I am going to be using with a LCD that uses a 2 wire I2C interface but the LCD runs at 5v so I will need a logic convertor. Also I will be using this on a Li-Po battery so I will also need a Voltage booster. I know there is lots of logic converters and voltage booster boards but to save on wires and space, Is there a board that is a 3.3 to 5v Logic converter and a voltage booster all in one?

Are you certain that you need a logic level converter? I do not know MKR1000 and I do not know your LCD but most 3.3 volt logic can drive most 5 volt logic. It is the other direction that can be a problem. Read the documentation for Vol, Vil, Voh, and Vih.

Of course, the I2C bus should be pulled up to 3.3 volts and not 5volts.

Well I’m new to I2C so maybe I don’t need a logic convertor. Can I2C work one way or does it need to be bi directional?

Needs to be bidirectional. Master sends out a byte, slave acknowledges with a 9th bit.

The data line needs to be bidirectional. Use a pullup resistor to 3.3 volts.
The clock line is unidirectional unless you have more than one master. Use a pullup resistor to 3.3 volts.

Devices only float their outputs or pull down to ground. The pullup resistors determine the high voltage.

The clock line is unidirectional unless you have more than one master. Use a pullup resistor to 3.3 volts.

Incorrect. In the I2C spec slaves are permitted to stretch the clock by holding it low if they need time to do something. Whether or not a particular slave does this will probably be listed in the datasheet.

True. Thanks! Does not change anything as long as no level converter is used and as long as the pullup resistors connect to 3.3 volts.

In fact, this configuration will work for multiple masters (but check the datasheets for Vih, Vil,Vol, and current into the output when the output is high).

Hi. The very same question here. Does a 5V I2C lcd 20x04 works with the MKR1000 without using a level shifter…?? YES, i gave it a try and it works. MKR specs says GPIO can “drive” 5V devices as long as they only accept not sending anything to mkr. I cant look under the hood i dont have any device what can read or see what is going on I2C bus.

Logic 1 threshold is 2 volts whilst logic 0 threshold is 0.8 volts. So long as both of you devices can achieve those levels, all should work.