In the project, there is a way to measure the magnetic field with a GMR Sensor, in which the GMR sensor transforms the values of the magnetic field strength into a corresponding voltage. In order to deal with the voltage signal, it is necessary to turn the values of the signal into digital and bring them into a computer.
A simple way is using an ATmega8A. It has a converting range from 0V to 5V. Compared to that, the GMR Sensor delivers a signal in the mV range. Therefore, an amplifier must be placed between the GMR sensor and the ATmega8.
An usually used chip is the AD698SQ. Before we put it in the circuit, we have to find the right external resistors and capacitances that match the chip.

November 19, 2009