Should I use a 4 channel Bi-Directional Logic Level Converter for the SDA, SCL, INT channels? or can I connect it directly to my arduino nano?
I saw some places that says I should use it with a logic level converter and some who say it's ok without it. (I guess it depends on the board, so please take a look, link above)
An Arduino Uno can be used without level shifter, but reading a 3.3V signal of the SDA or SCL is on the edge of the specification.
It will work without level shifter, but to be within the specifications you need a level shifter.
An Arduino Leonardo recognized a logic '1' at a lower voltage. So the Leonardo is compatible with 3.3V signals for inputs.
How to connect the level shifter, depends on what level shifter you have. Some have a 3.3V voltage controller on the board.
That is the ATmega328p microcontroller, just like the one in the Arduino Uno.
So it is like I wrote: "It will work without level shifter, but to be within the specifications you need a level shifter".
Hey Erdin, could you explain it a little bit more precisely for me because I don't get it. If he use the sensor with 3.3V or 5V he is always within the specification since his sensor works between 3 and 5V and the sensor will be working perfectly right ?
I don't see why he would be on the edge of the specification or outside of it (since you said : "to be within the specification you need a level shifter" I assumed that without it you're not within the specification).
Excuse me if my question seems stupid but I just want to get it =).
So the 0.6 * Vcc is guaranteed that it will read a digital input voltage as HIGH.
Suppose Vcc = 5.10V and the sensor is at 3.2V.
0.6 * 5.05 = 3.06 (minimum required)
According to this calculation it is within the specifications.
Assuming that the pullup resistor will pull the value above 3.06, it is guaranteed to work.
However, the margin is a about 200mV, that is not a lot.
I read other calculations that use 0.7 * Vcc, but the datasheet is clear, for 5V or 3.3V ATmega328p it is 0.6 * Vcc.
I just noticed that the arduino nano can't output 3.3V with external power output, that means I wont be able to use a level converter? (because I can't give the converter 3.3V)
I don't know what problem the level converter could cause, I ment it as a common note: the simpler it is, the less chance for error. And it will work without.
I use these, they have a 3.3V voltage controller on board.
I use them for my 3.3V standalone Arduinos, which are I2C Slaves.
You mean when using the Vin to power it, there is no 3.3V.
That is not possible. Please check it again. If you are sure that is the case, the board is defect.
Sorry!
I somehow didn't read that. After 3 posts of you, I finally got it.....
I did check the schematic, and I thought that the FTDI was powered with the same 5V as the ATmega328p.
I have a Nano, I should test it someday.
You can use that AMS1117 LDO board, or use the level shifter that I use with onboard voltage regulator.
I tested my Arduino Nano, and the FTDI chip is always powered. This is according to the schematic. I used Vin to power it, and the 3.3V was a valid output of 3.3V.
Perhaps that line about the FTDI chip only powered by the usb is for a previous version.
