8255 PPI CHIP ARCHITECTURE PDF

input device with the output device or vice-versa. In order to make it simpler, Intel has designed A chip to interface I/O devices. The Intel A is a general. A Programmable Peripheral Interface in Microprocessor – A Programmable Peripheral The following figure shows the architecture of A −. The (or i) programmable peripheral interface (PPI) chip was developed and manufactured by Intel The PPI chip Architecture.

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Digital Logic Design Interview Questions. After the reset is removed the A can remain in the input mode with no additional Initialization required.

Both “pull-up” and “pull-down” bus-hold devices are present on Port A. Both Inputs and Outputs are latched. This means that data can be input or output on the same eight lines PA0 – PA7. Each 4-bit port contains a 4-bit latch and it can be used for the controls signal outputs and status signal inputs in conjunction architecturre ports A and B.

This port can be divided into two 4-bit ports under the mode control. It consists of data bus buffer, control logic and Group A and Group B controls.

The A contains three 8-bit ports AB, and C. Report Attrition rate dips in corporate India: In essence, it allows the CPU to “read from” the Analog Communication Interview Questions. For example, if port B and upper port C have to be initialized as input ports and lower port C and port A as output ports all in mode Jobs in Meghalaya Jobs in Shillong.

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This mode is selected when D 7 bit of the Control Word Register is 1.

A “high” on this input initializes the control register to 9Bh and all ports A, B, C are set to the input mode. Embedded C Interview Questions. How to design your resume? The two modes are selected on the basis of the value present at the D 7 bit of the control word register. These three ports are further classified into two groups, i. Popular Tags Blog Archives. If bit 7 of the control word is a logical 0 then each bit of the port C can be set or reset. When we wish to use port A or port B for handshake strobed input qrchitecture output operation, we initialise that port in mode 1 port A and port B can be initilalised to operate in different modes, i.

This functional configuration provides simple input operations for each of the three ports.

Programmable Peripheral Interface

A “low” on this input pin enables the communcation architecthre the and the CPU. Retrieved 3 June Digital Electronics Practice Tests.

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They are normally connected to the least significant bits of the address bus A0 and A1. Control words and status informa-tion are also transferred through the data bus buffer. Views Read Edit View history.

8255 Programmable Peripheral Interface

Ports A, B, and C. The two halves of port C can be either used together as an additional 8-bit port, or they can be used as individual 4-bit ports.

This allows a single A to service a variety of peripheral devices with a simple software maintenance routine. The control logic block accepts control bus signals as well as inputs from the address bus, and issues commands to the individual group chp blocks Group A control and Group B control. Only port A can be initialized in this mode. Read operation of the Control Word Register is allowed. The 5-bit control port Port C is used for control and status for the 8-bit,bi-directional bus port Port A.

Making a great Resume: CS Chip Select Input. So, without latching, the outputs would become invalid as soon as the write cycle finishes.