The project of A sensor-driven mood lamp in week four Meeting

In week four meeting, initially, students test the operational amplifier.

The equation of the relationship between the output voltage and input voltage were given. The input voltage was measured 2.4 V and the output voltage was recorded 3.3 V, then the ratio of resister R2 / R1 equaled to 0.375. Students attempted to utilize 100 ohm (R1) and 375 ohm (R2) to compose the final operational amplifier, however, when the amplifier was applied in the actual circuit, the LEDs was always light brightly whether the infrared sensor was covered by hand. Then students tried to change their scheme by purchasing a new infrared sensor with the built-in operational amplifier for substituting the original one. Next, one student searched an appropriate infrared sensor in the website and copied one figure in the follow.

Then, the code of  infrared sensor was written by one group student. The whole code would not be shown in the blog because it was a complicated code to be explained in detail. The code mainly implemented functions of  handling the signal. For instance, when the output of IR was 0, the code was operated and calculated by the microprocessor and the nine LEDs would be shine for the outcome.
There was another important issue to clarify that there existed some problems with the Arm 7 board. For instance, the microprocessor board only worked for 10 seconds and overloaded later. Thus, students thought that the Arduino board was a more sensible choice than Arm board. Finally the teacher agreed the students' request for changing the microprocessor board. And the students would research the Arduino board code in the later days of this week.  

Finally, students designed the structure of the circuit diagram which was a little bit different from the original one designed initially, and the final circuit diagram would be drawn in the fifth week.