I have tested one ADXL377 Accelerometer on Arduino UNO, with DEFAULT analog reference and with external 3V3 reference and works fine with both (better with 3V3 because ADXL377 works on 3V3).
Then I tried to connect in the arduino Pro mini (5V, 16MHZ) with DEFAULT analog reference, since the AREF pin is not available) and with the same code.
In the Pro mini de values are bouncing around and the sensor doesn't work.
Anyone have an idea about what could be the problem?
Since the microcontroller are equals (atmega 328) I'm not getting what the problem could be.
I will appreciate any idea.
What accelerometer module are you using, and how is it wired to the Pro Mini? Does the module have a voltage regulator (the accelerometer cannot tolerate 5V)?
I’m using the ADXL377 module (ADXL337 and ADXL377 Accelerometer Hookup Guide - learn.sparkfun.com), the connections to the pro mini are in the attached figure. ( The components reference aren’t exactly the same but the connections are like this.
I have one 5V regulator to the arduino and one 3v3 regulator to the sensor.
The accelerometer can’t tolerate 5V.
If you really have the system connected exactly as shown in the attached PNG image, then you have failed to add the input/output capacitors required for the voltage regulators. The regulators are not guaranteed to be stable if you leave those out.
Study the data sheets for the voltage regulators you are using, and carefully follow the manufacturer's recommendations.
It would be easier to use a 3.3V Pro Mini instead, and provide all power to the RAW voltage input.