Design of acid rain observing instrument based on LPC2368

The acid rain observation system usually includes the measurements and analysis of pH value and electric conductivity. The measuring principles of pH value and electric conductivity are discussed in the paper. An acid rain observing instrument is developed, which uses ARM microcomputer LPC2368 as control core, and pH composite glass electrode, platinum black electric conductivity electrode and platinum resistance-Pt 100 as sensitive devices. It not only has high measuring accuracies by using the AD7792 as analog-digital conversion chip, but also has advantages in low cost, small volume and low power consumption. In addition, SD card is adopted to store the measuring data and CAN bus is used to communicate with PC to build acid observing network. The tests indicate that the acid rain observing instrument services high measuring accuracies for the pH value and electric conductivity of acid and provides important reference information for environmental monitoring.