**Measuring Tilt using a Three Axis Solution**

In order to define the angles of the accelerometer in three dimensions the pitch, roll and theta are sensed using all three outputs of the accelerometer. Pitch (ρ) is defined as the angle of the X-axis relative to ground. Roll (ϕ) is defined as the angle of the Y-axis relative to the ground. Theta (θ) is the angle of the Z axis relative to gravity.

http://www.freescale.com/files/senso...ote/AN3461.pdf

Here is the meat of the code:

solveangle: '**********Solve for x angle ******************************************** if xresult < yresult + zresult then dummy = 5000 'when x is smaller the following equation works best xlong = (dummy * xresult) /(sqr((yresult*yresult) + (zresult*zresult))) else 'keeps results accurate at near 0 and near 90 degree values dummy =30 'when x is larger the following equation works best xlong = (dummy * xresult*xresult) / ((yresult*yresult)+(zresult*zresult)) endif y = xlong x = dummy 'Assign x and y values for atan2 function call atan2 xangle = 9000 - y if yresult < xresult + zresult then dummy = 5000 'when y is smaller the following eqauation works best ylong = (dummy * yresult) / (sqr((xresult*xresult) + (zresult*zresult))) else dummy =30 'when y is larger the following equation works best ylong = (dummy * yresult*yresult) / ((xresult*xresult)+(zresult*zresult)) endif y = ylong x = dummy ' call atan2 yangle = 9000 - y

## Re: Re-using pins while still connected to MAX7219 ?

It's in the data sheet.

Dave Today, 12:00Load-Data Input. The last 16 bits of serial data are latched on LOAD’s rising edge.

So, Just hold the LOAD pin low until you have the new data shifted into the MAX7219....