2
\$\begingroup\$

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)

\$\endgroup\$
2
1
\$\begingroup\$

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

\$\endgroup\$
1
0
\$\begingroup\$

I have successfully run for a short time (minutes) this accelerometer (the "GY-521") without any logic level conversion. I haven't run it for any extended period of time, so I can't say for sure that doing so wouldn't permanently damage it, nor can I say the time I've run it so far hasn't already damaged it.

I may have hooked 3V3 to VCC.

However, I would have expected the magic smoke to come out fairly quickly.

Wiring a GY-521 to an Arduino Uno R3? addresses the necessary steps to connect this sensor to an Arduino.

The discussion on the arduino.cc forums regarding your question points out that a 3V3 logic high is sufficient to trip the logic high on an ATMega328, so it will work, and I've seen myself that 5V comms to the module succeeds. The forums suggest a $2 logic level converter is the best way to keep everything within specification, rather than working through happy coincidence for an indeterminate period.

\$\endgroup\$
3
  • \$\begingroup\$ Thanks, but the arduino nano doesn't have a 3.3V output with power from external source (which is what I plan to do). [from arduino.cc/en/Main/ArduinoBoardNano "when running on external (non-USB) power, the 3.3V output (which is supplied by the FTDI chip) is not available"] \$\endgroup\$ Aug 4 '13 at 16:46
  • \$\begingroup\$ So can I use this ebay.com/itm/… to convert the 5v to 3.3v (for the logic level converter Low Voltage pin)? \$\endgroup\$ Aug 4 '13 at 16:49
  • 1
    \$\begingroup\$ The buck down converter en.wikipedia.org/wiki/Buck_converter you linked to isn't necessary to supply 3V3, I've just tested my Nano's 3V3 output and it's live when sufficient voltage is supplied to Vin. Don't believe the documentation. \$\endgroup\$
    – Josh
    Aug 10 '13 at 11:02

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.