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A dual axis spirit level that uses a MPU-6050 Motion Tracking Sensor and is displayed on a 8x8 LED matrix.

Many years ago I bought a fancy square 8x8 Matrix LED from Futurlec. They aren’t expensive (around $2 each), they just seemed to be always out of stock whenever I ordered them. Anyway one did arrive and I have been keeping it for a special project so that I could show it off. This project seemed to be the right fit for it.

My primary goal when designing this project was keeping the size as small as possible. I didn’t want it to be any wider than the LED matrix itself and being as thin as possible. Rather than use a MAX7219 driver chip like most display boards use to mange the LED matrix, I decided to use a AVR128DB32 microprocessor and have it control the matrix as well as processing the information coming from the MPU-6050 Motion Tracking Sensor.

As you can see from the above schematic, there are very few parts. The VERT and HORZ trim-pots ended up being redundant so you can leave them off your build if you wish.

There are no current limiting resistors. The amount of power to each LED is controlled in the software using a technique called Bit Angle Modulation or BAM for short. I tried to describe how this works in my Red/Green/Blue Disco Tile project. It performs in a similar manner to PWM.

The sensor used is a MPU-6050 Motion Tracking Sensor that is incorporated on the GY-521 module. This tracks movement and acceleration in all three planes and communicates to the microprocessor using the I2C protocol. This project only uses the values for the movement in the X and Y planes. The GY-521 module is mounted in the center of the board directly under the LED matrix.”

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