Generating PORT Address for I/O Microprocessor and Interfacing by Ravinder Nath Rajotiya - October 12, 2021October 12, 20210 Generating the Ports for interfacing There are two techniques or methods for interfacing i/o devices, these are: i/o-Mapped I/O- In this method, the i/o device have separate address space and instructions exclusively for inputting or outputting the data from/to the devices. Instructions for reading/writing memory are different than i/o instructions.IN and OUT are used for i/o devices, and MOV is used for memory related operations. memory-mapped I/O- This techniques uses the common address space and instructions for communicating with the memory or the i/o. MOV instruction is used for i/o as well as memory related operations. In the following paragraph we will learn how to create the port addresses for the i/o-mapped i/o technique. We will use some address decoding logic gates for
8255 PPI(Programmable Peripheral Interface) Microprocessor and Interfacing by Ravinder Nath Rajotiya - March 26, 2020April 21, 20220 8255 Programmable Peripheral Interface 8255 is a programmable peripheral interface IC which is used as an interface between the external device and the microprocessor for parallel communication. This IC is a 40-pi IC having three ports known as Port-A(PA), Port-B(PB) and Port-C(PC). these ports can operate in various modes. the complete details is given in the following PPTSs. Features of the 8255: It provide three I/O ports All the three I/O ports are latched Port operation is configurable by programming 8255 i.e. writing a control word in CWR BSR- bit set-reset mode allows individual pins of port C to be controlled to be set or reset. PIN diagram of 8255 8255 PPI is a 40-pin IC, it has three 8-bit ports named PA, PB