What is the IO control word for 8255?
As indicated in Fig, the most significant bit (D_7) of the control word specifies either I/O function or the BIT set/ reset function. With D_7= 1, the 8255 works in the I/O modes. Port-C operates in BIT SET/RESET (BSR) mode with D_7=0. The BSR Mode in no way affects the functioning of port-A and port-B.
What is the function of 8255?
Function. The 8255 gives a CPU or digital system access to programmable parallel I/O. The 8255 has 24 input/output pins. These are divided into three 8-bit ports (A, B, C).
What is 82C55A?
DATASHEET. The Intersil 82C55A is a high performance CMOS version of the industry standard 8255A and is manufactured using a self-aligned silicon gate CMOS process (Scaled SAJI IV). It is a general purpose programmable I/O device which may be used with many different microprocessors.
How many pins of the 8255 can be used as the I O ports?
Explanation: There are 3 ports available in the 8255 so 24 pins are available for the I/O ports pins.
What is the purpose of using PIO 8255 in microprocessor based system?
PPI 8255 is a general purpose programmable I/O device designed to interface the CPU with its outside world such as ADC, DAC, keyboard etc. We can program it according to the given condition. It can be used with almost any microprocessor.
Why is 8255 needed?
8255 is a popularly used parallel, programmable input-output device. It can be used to transfer data under various condition from simple input-output to interrupt input-output.
Why do we need 8255?
PPI 8255 is a general purpose programmable I/O device designed to interface the CPU with its outside world such as ADC, DAC, keyboard etc. We can program it according to the given condition. It can be used with almost any microprocessor. It consists of three 8-bit bidirectional I/O ports i.e. PORT A, PORT B and PORT C.
How many ports 8255 A has?
three ports
8255A has three ports, i.e., PORT A, PORT B, and PORT C.
How many Address & data lines are available in 8255?
There are 24 input/output pins for the 8255. These are split into three ports that are 8-bit (A, B, C). It is possible to use Port A and Port B as 8-bit input/output ports.
What is DAC in microcontroller?
The Digital to Analog converter (DAC) is a device, that is widely used for converting digital pulses to analog signals. There are two methods of converting digital signals to analog signals. These two methods are binary weighted method and R/2R ladder method.
What are the direction of the I / O pins on the 8255?
Furthermore, the MOS devices allow the direction (input or output) of all their I/O pins to be individually programmed. The 8255 I/O pins have only four programmable direction bits: one for all of Port A (7:0), one for Port B (7:0), one for Port C (3:0) and one for Port C (7:4).
When does D 7 = 1, 8255 operate in I / O mode?
When D 7 = 1, 8255 operates in I/O mode, and when D 7 = 0, it operates in the BSR mode. The Bit Set/Reset (BSR) mode is available on port C only. Each line of port C (PC 7 – PC 0) can be set or reset by writing a suitable value to the control word register.
Is the 8255 microprocessor a general purpose device?
The 8255 is a general purpose programmable IO device. It is designed to interface the CPU with some external devices like ADC, DAC, keyboard etc. We can program the device according to the given condition. There are three 8-bit bi-directional IO ports. The Port-A, Port-B and Port-C.
What is the I / O mode of the Intel 8255?
Input/Output mode (I/O mode). The two modes are selected on the basis of the value present at the D 7 bit of the control word register. When D 7 = 1, 8255 operates in I/O mode, and when D 7 = 0, it operates in the BSR mode. The Bit Set/Reset (BSR) mode is available on port C only.