Calibration of ADXL335 Gesture Recognition Sensor interfaced with 8051

ADXL is an accelerometer sensor used to take a signal based on human gestures, it needs a calibration to adjust in order to get a signal from sensor for different motions. In this article we are going to discuss about calibration process using 8051 microcontroller.

In 8051/52 architecture doesn’t have Analog to Digital converter, so need to interface an ADC feature to your circuit. LM324 is an OpAmp based comparator IC, which can convert analog voltage to digital.

LM324 has four OpAmp, so that this IC can able to convert signals from four sensors. OpAmp has two input pins – Inverting Pin (-) and Non Inverting Pin (+). Where Signal of ADXL sensor have to connect with Inverting Pin and a Potentiometer with Non Inverting pin to set a reference voltage.

Calibration

Connect ADXL X axis pin with OpAmp 3,4 and Y axis to OpAmp 1 and 2. Hold the sensor in straight position and calibrate for that condition as 0101 using POT and LED’s. Once this calibration is done, you can get the values for other movements also.