MMA7341LC XYZ-axis accelerometer's equation

Hi everyone,
I would like to know the equation in order to get the x,y,z value from MMA7341LC 3-Axis Accelerometer ±3/9g(Pololu item #: 1247). I am going to use it with Arduino.
Additionally, do I need to use capacitors as the chipset’s document.
Kind Regards,
John
PS
Product Link - pololu.com/product/1247
Chipset document Link - pololu.com/file/download/MM … e_id=0J473

Hello.

We describe how to interpret the raw X, Y, Z, outputs from that sensor under the “Using the sensor” section of its product page:

As for capacitors, we have already added 3.3nF caps on each of the axis outputs, and a 0.1uF cap between VDD and GND per the notes under the Basic Connections section of the accelerometer’s datasheet. You can find a schematic of that board under the Resources tab of its product page.

-Jon

Hi Jon,
Thanks for your reply.
So, all I need to do is give high voltage to “sleep” pin in order to use the board.
Additionally, leave the “g-select” pin while using it with “3g” and give high voltage if it is used with “9g”. Is it correct?
There is one thing, I am going to use with 5V micro-controller. I think, I need to use logic level converter to control “g-select” and “sleep” pin. And also the same for the output of x,y,z (in order to get accurate result). Is it also correct?

Kind Regards,
John

Yes, what you said about the g-Select pin is correct, and you should drive nSLEEP high to enable the board. Like we also mention on the product page, you can make a solder bridge across the SMT jumper pads labeled “ON” on the silkscreen side of the board to connect the nSLEEP pin to VDD and enable the board by default.

If, instead, you want control over nSLEEP and g-Select, you should use level-shifters since you plan on using a 5V microcontroller. (If you do not have one in mind, you might consider using our level shifter.) As for the accelerometer outputs, those are just analog voltages that you should use with ADC inputs. So, you should not need to use level shifters.

-Jon

Hi everyone,
I got the sensors values these close to VDD even is not move.
I use logic level converter while reading the value from sensor.
Sensor value in even stable(don’t move the sensor) stage - 962 (analog to digital value) in 1023.

Kind Regards,
John

Hi everyone,
I got around 2.9 Voltage even in not moving stage (actually it should be around 1.65Voltage ( VDD/2 or 3.3/2 ).
Is the sensor fault.
Kind Regards,
John

Since you connected logic level shifters to the outputs of the accelerometer, the signals you are reading will always be translated, so what you reading makes sense. You should remove the logic level shifters and read the output pins directly with ADC inputs. By the way, I deleted your other new thread, since it was the same question as the initial post in this thread.

-Jon

Hi JonathanKosh,
I got the clue. And finally it work. But one thing, how to convert V to G value. Is there any equation.
Like how many voltage is equivalent to 1G. Something like that.
Kind Regards,
John

I mentioned this in my initial reply; the proper value to convert the analog voltage to units of g depends on the what sensitivity you have selected. For the MMA7341LC, if g-Select is low (±3g), the sensitivity is 440 mV/g, and if g-Select is high (±9g), the sensitivity is 118 mV/g.

-Jon

Hi JonathanKosh,
Everything is fine. Thanks for your help. I am really :smiley: happy with your Pololu’s customer service. What I found is that your company is difference from some (they are very very rude).
Thank guys
Kind Regards,
John

Dear Jon,
i hope this thread is still alive.
I just bought MMA7341LC XYZ-axis accelerometer, and it works fine, measures the acceleration correctly, the output voltages are around 1,5V, but all the three outputs are same, no matter in which direction I move it.
Could you help with my problem?

Thanks,
Daniel

Hello, Daniel.

Can you tell me more about how you are using it? How are you supplying power? How are you reading the outputs? Can you also post pictures that clearly show your connections and soldering joints?

-Jon