1. Group Project: Water Turbidity Meter Group B

2. Brief overview Project Statement: “Design and construct a turbidity measuring and displaying device based on the HC08QY4 microcontroller” Integral components are the microcontroller mentioned above, an LDR, an LED, and the 7 segment display

3. What is turbidity? Turbidity is a “measure of the collective optical properties of a water sample that cause light to be scattered and absorbed rather than transmitted in straight lines (USGS 04/96).” The quantity of suspended solids in a water sample Indicates how potentially polluted a water sample is

4. The Design

5. Our design LED functions as constant light source LED functions as constant light source LDR at set distance from LED measures light intensity LDR at set distance from LED measures light intensity Resistance of LDR varies according to intensity of light, providing an indication of water clarity Resistance of LDR varies according to intensity of light, providing an indication of water clarity Microcontroller records voltage drop over LDR every 15 seconds Microcontroller records voltage drop over LDR every 15 seconds Above measurement converted to a percentage of turbidity, displayed on 7 segment display Above measurement converted to a percentage of turbidity, displayed on 7 segment display 0% indicates perfect transparency (clean water); 100% is total light dispersion (very dirty water) 0% indicates perfect transparency (clean water); 100% is total light dispersion (very dirty water)

6. Circuit diagram Changed

7. Problems

8. Hardware problems/solutions Almost identical to original design Almost identical to original design -Resistors with sensor dropped -Op-amp changed to buffer -Voltage regulator malfunctioned, was replaced -One 7 segment display malfunctioned, was replaced -Electrical problem on micro-controller board caused errors when writing to display, fixed after lengthy diagnosis of problem, turned out to be solder hole

9. Software problems/solutions Only minor problems/changes from original design: Only minor problems/changes from original design: -A/D using coco bit was discarded for interrupt routine -Table of values changed to improve accuracy of device

10. The final product

11. How the hardware works LED as constant light source LED as constant light source LDR voltage varies according to light intensity LDR voltage varies according to light intensity This signal passes through op-amp buffer This signal passes through op-amp buffer Micro-controller receives signal, converts to digital Micro-controller receives signal, converts to digital Corresponding percentage sent to display Corresponding percentage sent to display

12. How the software works System ready to receive data, calibration completed, turbidity output to be determined by preset voltages System ready to receive data, calibration completed, turbidity output to be determined by preset voltages Analogue signal received by micro, A/D conversion Analogue signal received by micro, A/D conversion Digital value looked up in pre written table, corresponding turbidity output percentage found Digital value looked up in pre written table, corresponding turbidity output percentage found Output percentage (00 to 99) sent to display Output percentage (00 to 99) sent to display Timer delay of 15 seconds Timer delay of 15 seconds Repeat process Repeat process

13. Demo

14. Questions?