Week 6 (9 to 15/9/2012)

For this week, all the students were briefed on the details that must be made in the report and the marks given for each item. FYP calendar is also provided so that students can refer.

In this week I also took do research for the components in my project.

Temperature sensor

From the block diagram, the first part is the temperature sensor. The temperature sensor that will be used in this project is LM 35 temperature sensor. The LM35 series are precision integrated-circuit LM35 temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 sensor thus has an advantage over linear temperature sensors calibrated in ° Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 sensor does not require any external calibration or trimming to provide typical accuracies of ±¼°C at room temperature and ±¾°C over a full -55 to +150°C temperature range.

The reason this project picked this temperature sensor is because low cost is assured by trimming and calibration at the wafer level. Also, the LM35's low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with single power supplies, or with plus and minus supplies. As it draws only 60 µA from its supply, it has very low self-heating, less than 0.1°C in still air. The LM35 is rated to operate over a -55° to +150°C temperature range, while the LM35C sensor is rated for a -40° to +110°C range (-10° with improved accuracy). 

 Motor Driver (Transistor N-MOSFET)

For the next part, this project will need a motor driver. The motor can be controlled by a switch, but the most common way to control a motor is through a transistor. This is because transistor can act as a switch too. Transistor is better when dealing with larger items (like a toy motor or washing machine). A transistor is incredibly useful because it switches a lot of current using a much smaller current. A transistor has 3 pins. For a negative type (NPN) transistor you connect your load to collector and the emitter to ground. Then when a small current flows from base to the emitter a current will flow through the transistor and the motor will spin.

There are two types of standard transistors, NPN and PNP, with different circuit symbols. The letters refer to the layers of semiconductor material used to make the transistor. Most transistors used today are NPN because this is the easiest type to make from silicon.

1) Arduino Microcontroller

As mentioned above, this project will use the microcontroller Arduino. Arduino is an open-source single board microcontroller. The reason this project picked this particular microcontroller is because the programming for it is more user friendly compared to other microcontrollers. For the Arduino hardware, the Arduino board consists of an 8-bit Atmel AVR microcontroller with complementary components to facilitate programming and incorporation into other circuits. An important aspect of the Arduino is the standard way that connectors are exposed, allowing the CPU board to be connected to a variety of interchangeable add-on modules known as shields. Some shields communicate with the Arduino board directly over various pins, but many shields are individually addressable via an I²C serial bus, allowing many shields to be stacked and used in parallel. Besides that, Arduino also pre-programmed with a boot loader which will make it easier to upload programs to the on-chip flash memory, while other devices need to use an external programmer.

So those components above are some that I will use for my project.