Tutor profile: Matty M.
Subject: Electrical Engineering
How do you decided what size electrical wires you need?
The size of the wires required for your project all depends on the amount of current that will be flowing through your circuit. Think of current in a wire like water flowing through a hose, if you tried to hook a garden hose to a fire truck the hose would be damaged from the pressure of the water coming from the firetruck. A garden hose is simply not designed to handle that much water pressure. The same goes for electrical wires. If you use a wire that is not rated for the amount of current that will be flowing through it, it will begin to get hot and if left on long enough it could even catch fire. Electrical Wire ratings can be found by referencing the America Wire Gauge System. The rating system is opposite what you would expect as a 14 gauge wire can handle less current than a 10 gauge wire.
Subject: Arduino Programming
Write the output of the following code and explain: Serial.print(65); Serial.write(65);
Assuming that serial communication has been started with Serial.begin(9600), the code would output the following: 65A This is because the Serial.print function is used to print string or character values to serial. Arduino will automatically convert the number 65 into the character equivalents '6' and '5' and it will print them to the terminal. The Serial.write function is used to write raw binary values to the terminal which will be interpreted accordingly. When calling Serial.write(65), Arduino writes the value 65 to the terminal which is interpreted as the letter 'A'. This is due to the difference in the way computers handle numbers and letters. Each "letter" that we see as humans is represented by a number to the computer. By referencing the ASCII Table, we see that the decimal value of 'A' is 65. Serial.write(65) writes the value of 65 to the terminal, and since the terminal wants to print readable string or character values it automatically converts that number 65 to the character equivalent which is 'A'
Subject: Android Programming
In order to display data in a custom ListView, we must have 4 elements. What are they and what are their roles?
The 4 elements required to show custom data in a Listivew are: the data, an adapter, a custom xml layout and a ListView object. The data usually comes in the form of a List or ArrayList of custom objects. This is the information that will be shown in the Listview. An XML layout file is created to define what xml elements will be in each row of your ListView. This defines the look of our custom ListView. A custom array adapter class will be made for our Listview. The adapter tells Android which data should be put where on the layout file. For example, let's say we have list of data for Car objects. Each car object has a manufacturer, model and color. Our custom XML layout would have 3 text views, txtManufacturer, txtModel, and txtColor, in the layout of our choice. The adapter is defined to access a Car object and assign the value of the manufacturer to txtManufacturer, the value of the model to txtModel, and the value of .the color to txtColor. It creates a row in our listview for each object in the data list. Lastly, we need a Listview to show our data in. We need to set the adapter of the listview to be our custom adapter and then we would be able to show custom data in a listview in our app.
needs and Matty will reply soon.