Which register Is allowed to be used as a pointer for register indirect addressi
ID: 3823514 • Letter: W
Question
Which register Is allowed to be used as a pointer for register indirect addressing when accessing data stored in program ROM? Give the name and show how it is used Write a program that will read the following message from ROM and place it in data RAM starting at 100: a. How many pins does the LCD used in your project have? b. What is the purpose of each pin? c. In sending data to the LCD how many bits can be send to it at a time? In a DC motor how can the rotation direction be controlled? What is Pulse Width Modulation? And How is it used dc motor control?Explanation / Answer
9) In a DC motor how can the rotation direction be controlled..?
In a DC motor the rotation direction can be controlled in different ways.
1)Low Voltage DC motors :
The small DC motors which has 12V or below 12V made up of permanent magnet . In order to change the direction of the shaft we only change the polarity. Because it contains only armature winding. Their is one more method which is to use an H-bridge which controls the direction of a DC motor. It is a special circuit which allows motor rotation in both directions. From four terminals of a H bridge you can control the direction of a DC motor.
2)High Voltage DC motors :
The high voltage DC motors which has 220V or above 220V made up of temporary magnet . So if we change the polarity of the supply the total circuit will change. Due to that the motor will rotate in normal direction. If we want to change the direction of the shaft we need to change either field or armature supply.
10) Pulse width modulation: Pulse Width Modulation is a technique for getting analog results with digital means. Digital control is used to create a square wave, a signal switched between on and off.
How it is used in dc motor control ..?
a)Pulse width modulation is used to control a small motor.It has the advantage in that the power loss in the switching transistor is small because the transistor is either fully “ON” or fully “OFF”. As a result the switching transistor has a much reduced power dissipation giving it a linear type of control which results in better speed stability. Also the amplitude of the motor voltage remains constant so the motor is always at full strength. The result is that the motor can be rotated much more slowly without it stalling. Pulse width modulation is a great method of controlling the amount of power delivered to a load without dissipating any wasted power.
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