Crazy values using gyro ENC-03

[Eduardo Camargo]

Hi,

I am having problems with my ENC-03M. When I stop rotating it, it returns values like it was being rotated in opposite direction and after some milliseconds (or even seconds) the value reaches the Vref. It seems to be measuring the angular ACCELERATION, instead the angular velocity. I have a graph of the values:



I tried using a 4.7uF capacitor in Vref and the results didn´t changed.

I have 3 boards with same behavior.

PS: Sorry my English, it isn´t my native language.

PS2: Please, don't tell me to read the datasheet. I already did it 138 time, approximately... =D

Thanks,

Eduardo

 

[chuckey]

As acceleration is Dv/dt, if you pass the output through an integrator (LPF), it should return v.
Frank

 

[Eduardo Camargo]

As acceleration is Dv/dt, if you pass the output through an integrator (LPF), it should return v.
Frank

Hi Chuckey,

Thanks, but shouldn't the device return velocity?

 

[chuckey]

GOT IT, This gizmo needs a very high impedance input impedance to work into. Perhaps because of some small series capacitive coupling to its output pin. If you operate it into a low impedance, its a differentiator, i.e. the input side of the capacitor, will be v, the signal on the output will be Dv/Dt.
Frank

 

[Eduardo Camargo]

GOT IT, This gizmo needs a very high impedance input impedance to work into. Perhaps because of some small series capacitive coupling to its output pin. If you operate it into a low impedance, its a differentiator, i.e. the input side of the capacitor, will be v, the signal on the output will be Dv/Dt.
Frank

Frank,

I think I didn´t get what you meant (I am not that "eletronic guy", actually I prefer writing software ). So are you telling me to add a capacitor to output...?

Note: I´m using this board:

 

[chuckey]

No, what I am saying is that there is already a capacitor in series with output signal somewhere. This is OK if the load on the other side of the capacitor is very high, if the load (resistance) is too low, the voltage across the resistor will be the differentiated version of the input voltage.
This may help :- https://en.wikipedia.org/wiki/Differentiator
Frank

 

[Eduardo Camargo]

No, what I am saying is that there is already a capacitor in series with output signal somewhere. This is OK if the load on the other side of the capacitor is very high, if the load (resistance) is too low, the voltage across the resistor will be the differentiated version of the input voltage.
This may help :- http://en.wikipedia.org/wiki/Differentiator
Frank

Frank,

I appreciate your help! I am trying to learn about Differentiator, but I still continue not getting why this board do that. It's supposed to return velocity, not acceleration (Dv/Dt), but I think you cannot answer that. :/

The board has a High Pass Filter, that seems to be acting like a differentiator according to the diagram in Wikipedia (http://arduinosolutions.com/upload/download/ENC-03M/Piezoelectric_Gyroscope.pdf).

Thanks... again!

Eduardo

 

[chuckey]

If your board has the same circuit as the sample one on the data sheet, increasing the value of the 100K resistor should improve things, try 1 M ohm. Or the 4.7 MFD capacitor is faulty or put in the wrong way round? In the wave form diagram what is the time scale? - Its labelled 100, 200. . .
You are using your CRO on DC?, on AC coupling, it will not respond much to 10 HZ signals.
Frank