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

In the fifth week before bench inspection, students attempted to solder the elements in the board and wire the board with the Arduino board and the LED driver. And the final finished product figure was shown in the follow.
However, due to the short distance between two cavities, the work of soldering was much more difficult than thought. Unfortunately, some wires were soldered together in the board which resulted in the
wrong result in this project. Thus, students abandoned soldering the circuit in the soldering board, and tried to wire the circuit on the bread board.  So, in the afternoon of this Friday, one student hammered at considering the appropriate code for the Arduino board, while another two students wired the circuit in the bread board. After around one hours, the final product was wired successfully and it was shown in the follow figure.

It could be seen that every LED has four pins, and the longest one was connected to the GND, while the other pins (red green blue) was connected to the 5V with a resistor of 330 ohm (high voltage). And the detail information of LED driver has been explained in the week three blog, and the pins in the LED driver were connected to the corresponding locations in the Arduino board. And every infrared sensor utilized three pins with one was connected to the GND, one was connected to the high voltage and one was wired to the output pin in the Arduino board. 

After the model was accomplished, the students would analyze the circuit with program processor in the later time and wrote the report as well.  

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. 

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

In week three meeting, students researched the circuit diagram of the operational amplifier.

The main function of an operational amplifier is to amplify the input signal, and the function is better with the more open loop gain (Avo). Open-loop gain of which values range from 20,000 to 200,000 is the gain of the op-amp without positive or negative feedback. Input impedance (Zin) is the ratio of input voltage to input current, and is assumed to be infinite to prevent any current flowing from the source supply into the amplifiers input circuitry. The output impedance (Zout) of the ideal operational amplifier is assumed to be zero acting as a perfect internal voltage source with no internal resistance so that it can supply as much current as necessary to the load. The Voltage Gain (Av) of the operational amplifier can be found utilizing the following formula: 

Voltage Gain, (A)=Vout/Vin 

and in Decibels or (dB) is given as:

20log(A) or 20logVout/Vin in dB 

After that, we understood the main function of this operational amplifier. Then, we tried to wire the circuit diagram of LED and took a video of that in the follow:

It could be seen that when the student's hand was closer to the receiver, the LED light was brighter. That phenomenon was conform to the situation for the distance sensor. 

And in the next week, students will connect all the elements in this design in one circuit and test it to acquire the result. 

Figure 1 shows the code of the ordinary situation we choose when starting the board.

Figure 1: demo code

After that, we started to test one group of RGB LEDs. LEDs were divided into two groups, one group were connected in series and two groups were connected in parallel.

The video shows one group of RGB LEDs shining after downloading the code.

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

In week two meeting, the group students are trying to make the circuit diagram design. Luckily, students already have an example found in the internet about the Arduino board with distance sensors. And the main schematic diagram was provided in the follow:

It could be concluded that students need some IR LED(emitter), IR Photodiode(detector), a Op-Amp Array(TLC274),a 16*4 MUX(CD74HC), an ARM board, a LED Driver(TLC5940) and some visible light LED. Maybe this schematic diagram could be the basic diagram of students' design.
Initially, in our design, a CD74HC4067 device is required which controlled analog switches that utilize silicon-gate CMOS technology to achieve operating speeds. Also students find the pin figure of CD74HC4067:

It could be summarized that pin 2-16 are regarded as IN0-IN15 which are connected to the Op-Amp Array. And pin 24 are connected to Vcc(5V), while pin 15 and 12 are connected to the ground. Next, pin 10, 11, 13, 14 should be connected to the ARM board as input to the multiplexor. Also the Truth Table of this device is provided in the figure shown below:

The sample logic relation is that the selected channel equals to S3S2S1S0 in binary system. For instance, if S3S2S1S0 equals to 0001, and the channel 1 is selected as expected. 

Then students try to understand the function of operational amplifiers. The TLC274 quad operational amplifiers combine a wide range of input offset voltage grades with low offset voltage drift, high input impedance, low noise, and speeds approaching that of general-purpose BiFET devices. Besides, the pin figure of this operational amplifier is provided:

The pin 1 14 7 and 8 are output pins needed to be connected to the receivers, while pin 2 3 13 12 5 6 9 10 are input pins which should be connected to the MUX. Moreover, pin 4 should be wired to VDD and pin 11 should be connected to ground. 

Then students would like to introduce the LED driver of TLC5940NT. The TLC5940 is a 16-channel, constant-current sink LED driver of which each channel has an individually adjustable 4096-step grayscale PWM brightness control. Students also find the pin figure of TLC5940NT:

 

The pin 1-15 and 28 are constant current output, pin 23 is BLANK which blank all outputs (when BLANK=H, all OUTn outputs are forced off), pin 19 is DCPRG which switch DC data input (when DCPRG=L, DC is connected to EEPROM), pin 22 is GND, pin 18 is GSCLK which is reference clock for grayscale PMW control, pin 20 is IREF which is connected to reference current terminal, pin 25 is SCLK which is connected to serial data shift clock, pin 26 is SIN which is serial data input, pin 17 is SOUT which is connected to serial data output, pin 21 is VCC connected to power supply voltage, pin 27 is VPRG which is multifunction input pin (When VPRG = GND, the device is in GS mode. When VPRG = VCC, the VPRG 27 6 3 I device is in DC mode), pin 16 is XERR which is error output, and pin 24 is XLAT which is level triggered latch signal (When XLAT = high, the TLC5940 writes data from the input shift XLAT 24 3 32 I register to either GS register).

Finally,some information of the main experimental material L-154A4SURKQBDZGW RGB LED is founded in the internet. 

The red source color devices are made with AlGainP on GaAs substrate Emitting Diode, the blue source color device are made with InGaN Light Emitting Diode,and the Green source color devices are made with InGaN on Sapphire Light Emitting Diode. 

Then, maybe in the next week, the group students will try to wire the circuit diagram in the bread board and fix some problem occured in the process of connection.

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

The group project is about design a sensor-driven mood lamp, and the main aim of this project is to develop a so-called mood lamp that utilizes a combination of a simple processor board and a set of sensor to change the light coming from the lamp. Students should order the components from the lab professor and build the hardwire side of the lamp. Moreover, students should have the ability to find information on how to use the ARM KL46Z and how to program it. Finally, students can choose some sensors to make the design more appropriately and usefully.
In first week. three students of this Yr2 project group met together in lab room and got the experiment materials (30 Leds and an ARM board) form the lab technicians. Before the meeting, one group student had read the FRDM-KL46Z user's

manual and was familiar with the hardware and software of FRDM-KL46Z. 

This device is form-factor compatible with the Ardunio R3 pin layout. The on-board interfaces includes a 4 digit segment LCD, a 3-axis digital accelerometer, magnetometer capacitive touch slider, and ambient light sensor. And two Figuress about the FRDM-KL46Z were provided in the follow:

The OpenSDA is an open-standard serial and debug adapter. It bridges serial and bug communication between a USB host and an embedded target processor. 

And for the software section, we need to get start with mbed with connecting the microcontroller to a PC and click the MBED.HTM link to get logged in. Then, students will be familiar with the basic program of this ARM board. Meanwhile, students can download a program by saving a program binary (.bin) to the FRDM Platform and pressing the reset button and then starting this program in the board.

Because this is the first week job, and students are not sure with many issues about how to connect the software and hardware together to make them as an entirely. And students are trying to draw the circuit diagram for their design. 

Maybe next week, students can build the basic circuit and write a basic code to drive the LED.