Mini Maestro and Accelerometer

Hello

(Warning: I’m relatively new at this)

I am trying to read values from a MMA7361L accelerometer through my mini maestro 12 channel however I’m starting to think there’s more to it than connecting the wires. Here is what I’ve done so far (no soldering and for now, using the Maestro control centre):

Wiring

  • Mini maestro connected to pc through mini usb cable
  • External power source(+/- 5V) connected to servo pins
  • Channel 4 is set as an input and connected to the x-axis of the accelerometer.
  • VDD of the accelerometer is connected to the 5V pin on my maestro
  • Channel 5 is configured as an output and connected to the sleep pin on the accelerometer (it is set at high input signal)

What happens:
When this is set the reading on the input channel 4 jumps around 233-236 and is totally unresponsive as I tilt the accelerometer. When I connect the ground to the accelerometer it just reads the value 0 unchanging. I can’t manage to get any readings with a multi meter at the accelerometers x-,y- and z-axis pins.

Now could you please tell me what is wrong here and how to fix it, or just how to interface the MMA7361L.
It will be greatly appreciated!!

Hi.

From your description of the pin outs, it sounds like you are using the Pololu #1246 version of this carrier. If so, note that the pins are not 5V-tolerant as highlighted in the “Using the sensor” section of the MMA7361L 3-Axis Accelerometer product page. The Maestro is a 5V device, so when you applied the 5V (that the Maestro produces) to the SLP pin, you likely damaged the MMA7361L 3-Axis Accelerometer carrier. I suggest using our #1251 version. The #1251 carrier does not have a sleep pin, so the higher voltage of the Maestro should not be a problem.

-Derrill