Explain keyboard and LCD interfacing with 8051.

Keyboard Interfacing with 8051:

1. The keyboard is one of the most common input devices used with computers. In the context of 8051 microcontroller, we often use a matrix keyboard. This is a simple and cost-effective method to give commands to the microcontroller.

2. The matrix keyboard is essentially a combination of push-buttons in a high-density I/O format. The most common configuration is a matrix of 4x4, which provides 16 keys.

3. The rows of the matrix keyboard are connected to the port pins (P1.0 - P1.3) and the columns are connected to P1.4 - P1.7. When a key is pressed, it connects a row with a column. The microcontroller scans the rows and columns to determine which key was pressed.

4. The 8051 microcontroller then processes this input and performs the corresponding action.

LCD Interfacing with 8051:

1. LCD (Liquid Crystal Display) is a type of display used in digital devices, which uses the light-modulating properties of liquid crystals. They are a lot more complex than LED displays due to the number of pins they have. However, they are very useful for displaying text.

2. The most commonly used LCDs found in the market today are 1 Line, 2 Line or 4 Line LCDs which have 16 Pins. Out of these 16 Pins, 8 are data lines (DB0 - DB7), 3 control lines, 2 power supply pins and 1 for contrast adjustment (VEE - used for controlling LCD contrast).

3. To interface LCD with 8051, we need at least 6 free ports. Data is transferred between the 8051 microcontroller and the LCD by connecting the data pins of the LCD to a port on the microcontroller (for example, port P2).

4. The control lines (RS, RW, E) are connected to the control pins of the 8051 microcontroller. The RS pin is used for selecting whether command or data is to be transferred with the LCD. The RW pin is used to tell the LCD whether we are writing to it or reading from it. The E pin is used to enable or disable the LCD.

5. Once the connections are made, we can send data or commands to the LCD by setting the appropriate control signals and then toggling the enable pin.

6. The 8051 microcontroller then processes this input and performs the corresponding action.

Keyboard Interfacing with 8051:

1. The keyboard is one of the most common input devices used with computers. Interfacing a keyboard with the 8051 involves connecting it to the input/output ports of the microcontroller.

2. The keyboard is usually interfaced with the microcontroller using a matrix keypad. This is a simple method where the keys are arranged in rows and columns.

3. The rows are connected to the output port and the columns are connected to the input port. When a key is pressed, a particular row and column get shorted.

4. The microcontroller scans the rows one by one by sending a logic 0 to a particular row and checking the columns. If a key is pressed, the corresponding column will also get a logic 0.

5. The microcontroller then identifies the key pressed by detecting the row and column that has been shorted.

LCD Interfacing with 8051:

1. LCD (Liquid Crystal Display) is a type of display used in digital watches and many portable computers. LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them.

2. The LCD is interfaced with the 8051 by connecting it to the output port of the microcontroller. The data pins of the LCD are connected to the port pins of the microcontroller.

3. The control pins (RS, RW, and E) of the LCD are also connected to the port pins of the microcontroller. RS is the register select pin, RW is the read/write pin, and E is the enable pin.

4. To send data to the LCD, the microcontroller sets the RS and RW pins to the appropriate logic levels, then sends a pulse to the E pin. The LCD reads the data on the data pins at the falling edge of the E pulse.

5. The microcontroller can also read data from the LCD by setting the RS and RW pins to the appropriate logic levels and sending a pulse to the E pin. The microcontroller reads the data on the data pins at the rising edge of the E pulse.