AVR Atmega MMA7455 accelerometer library 02 + processing

MMA7455 3-axis Accelerometer AVR Atmega library.

MMA7455 is a very low power 3 axis digital accelerometer from Freescale
Semiconductors. It's micro machined nano structure is capable of measuring
acceleration along its X, Y and Z axes.

User can setup sensitivity to 8bit, or 10bit, and measurement mode to 2/4/8G.
You should calibrate the sensor before use it, to calibrate it collect values
placing the accelerometer on every position of an ideal cube and then edit
calibration offset values.

For my tests calibration is done using the method proposed here: Using an Accelerometer for Inclination Sensing [Analog Devices]
A processing visualization tool is provided.
Attitude estimation can be done in firmware or in the visualization tool.
To estimate pitch and roll:

• normalize the accelerometer data
• use the equations suggested in the app note Tilt Sensing Using Linear Accelerometers [Freescale Semiconductor]
  pitch = -atan2(ax, sqrt(pow(ay,2) + pow(az, 2)));
  roll = atan2(ay, az);

Code

• avr_lib_mma7455_02.zip

Notes

• read risk disclaimer
• excuse my bad english