Electronic – arduino – GY-521 MPU-6050 + Arduino nano – Logic converter or not

arduinoconverterlevel-shiftinglogic-levelsensor

I bought this MPU-6050: link (marked as "GY-521" on the board)

According to the manufacturers' site, the sensor logic level is 3.3V (though the eBay page says Power supply :3-5v)

Should I use a 4 channel Bi-Directional Logic Level Converter (like this one) 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 sensor board, so please take a look, link above)

Current Setup:

SDA <-> LLC <-> A4
SCL <-> LLC <-> A5
INT <-> LLC <-> D2
VCC <- LLC <- 5V (arduino)
GND <- LLC <- GND (arduino)

I still don't have the parts so I can't test it, and I'm probably going to use Jeff Rowberg library to communicate with the sensor (I²C)

Best Answer

According to 28.2 in the Atmega (the microcontrollers used on the Arduino nano) datasheet, it looks like Vih(input high voltage) is 0.7V-0.8V at minimum. So you probably don't need a converter for the INT pin (since that is an output for the MPU, but you'd need a converter for everything else (since both SDA and SCL are input/output for the MPU and the Atmega).

The ebay site says 3-5V for the main supply because it looks like it has a regulator on board. As for the IO lines themselves, it's hard to say if it has any converters on board.

Atmega datasheet: http://www.atmel.com/Images/doc8161.pdf

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That website has a photo which shows "2-GND". This is the ground that you want to connect to the ground that you have for everything else.

As far as the 2.8v source, you can use any source you want. The voltage is just used to reference the serial signal against. If you tie it to the 3.3V it will probably work. I am not sure of the specifics of that voltage shifter, but I assume it will treat 2.8v on the signal line as being a logic high when comparing to 3.3v.

Electronic – arduino – How to read a gyro/accelerometer

The accelerometer's reading seem to make sense. The datasheet, page 13 indicates 4 different sensitivities:

with resp. sensitivity scale factors:

16 384 counts/g  
8 192 counts/g  
4 096 counts/g  
2 048 counts/g

From the Z-reading I assume you have the 2 g scale selected, then 15 608 is 0.95 g, which is what you can expect from a Z-axis reading when you hold the sensor more or less horizontal. The X- and Y-reading are probably also due to gravitation when you're not holding the part perfectly horizontal. And you'll have an error in the reading too.

Similar for the gyro. At 131 counts per degree/s you may have this kind of reading if you're holding the part in your hands.

Best Answer

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