8085 Microprocessor - Printable Version +- Free Academic Seminars And Projects Reports (https://easyreport.in) +-- Forum: Seminars Topics And Discussions (https://easyreport.in/forumdisplay.php?fid=30) +--- Forum: Miscellaneous Seminars Topics (https://easyreport.in/forumdisplay.php?fid=21) +---- Forum: General Seminar Topics (https://easyreport.in/forumdisplay.php?fid=58) +---- Thread: 8085 Microprocessor (/showthread.php?tid=12416) |
8085 Microprocessor - sandeep.ladu - 08-16-2017 8085 Microprocessor [attachment=738] Microprocessor Initiated Operations Memory Read Memory Write I/O Read I/O Write Internal Operations Store 8-bit data Perform Arithmetic and Logic Operations Test for conditions Sequence the execution of instructions Store/Retrieve data from stack during execution Peripheral/Externally Initiated Operations Reset Interrupt Ready Hold 8085 Communication with Memory Involves the following three steps Identify the memory location (with address) Generate Timing & Control signals Data transfer takes place Example: Memory Read Operation Timing Diagram Demultiplexing Address/Data Bus 8085 identifies a memory location with its 16 address lines, (AD0 to AD7) & (A8 to A15) 8085 performs data transfer using its data lines, AD0 to AD7 Lower order address bus & Data bus are multiplexed on same lines i.e. AD0 to AD7. Demultiplexing refers to separating Address & Data signals for read/write operations Need for Demultiplexing The 16-bit address of the memory location must be applied to the memory chip for the whole duration of the memory read/write operation. Lower-order address needs to be saved before microprocessor uses it for data transfer 8085 Interfacing with Memory chips 8085 Interfacing with Memory chips 8085 Interfacing with Memory chips Memory Mapping 8085 has 16-bit Address Bus The complete address space is thus given by the range of addresses 0000H FFH The range of addresses allocated to a memory device is known as its memory map Memory map: 64K memory device Address lines required: 16 (A0 A15) Memory map: 0000H - FFH So the memory map is Interfacing I/O devices with 8085 Peripheral-mapped I/O & Memory-mapped I/O Interfacing I/O devices with 8085 Techniques for I/O Interfacing Memory-mapped I/O Peripheral-mapped I/O Memory-mapped I/O 8085 uses its 16-bit address bus to identify a memory location Memory address space: 0000H to FFH 8085 needs to identify I/O devices also I/O devices can be interfaced using addresses from memory space 8085 treats such an I/O device as a memory location This is called Memory-mapped I/O Peripheral-mapped I/O 8085 has a separate 8-bit addressing scheme for I/O devices I/O address space: 00H to FFH This is called Peripheral-mapped I/O or I/O-mapped I/O 8085 Communication with I/O devices Involves the following three steps Identify the I/O device (with address) Generate Timing & Control signals Data transfer takes place 8085 communicates with a I/O device only if there is a Program Instruction to do so 1.Identify the I/O device (with address) Memory-mapped I/O (16-bit address) Peripheral-mapped I/O (8-bit address) 2.Generate Timing & Control Signals Memory-mapped I/O Reading Input: IO/M = 0, RD = 0 Write to Output: IO/M = 0, WR = 0 Peripheral-mapped I/O Reading Input: IO/M = 1, RD = 0 Write to Output: IO/M = 1, WR = 0 8085 Communication with I/O devices Involves the following three steps Identify the I/O device (with address) Generate Timing & Control signals Data transfer takes place 8085 communicates with a I/O device only if there is a Program Instruction to do so Peripheral I/O Instructions IN Instruction Inputs data from input device into the accumulator It is a 2-byte instruction Format: IN 8-bit port address Example: IN 01H OUT Instruction Outputs the contents of accumulator to an output device It is a 2-byte instruction Format: OUT 8-bit port address Example: OUT 02H Example Program WAP to read a number from input port (port address 01H) and display it on ASCII display connected to output port (port address 02H) IN 01H ;reads data value 03H (example)into ;accumulator, A = 03H MVI B, 30H;loads register B with 30H ADD B ;A = 33H, ASCII code for 3 OUT 02H ;display 3 on ASCII display Memory-mapped I/O Instructions I/O devices are identified by 16-bit addresses 8085 communicates with an I/O device as if it were one of the memory locations Memory related instructions are used For e.g. LDA, STA LDA 8000H Loads A with data read from input device with 16-bit address 8000H STA 8001H Stores (Outputs) contents of A to output device with 16-bit address 8001H Example Program WAP to read a number from input port (port address 8000H) and display it on ASCII display connected to output port (port address 8001H) LDA 8000H;reads data value 03H (example)into ;accumulator, A = 03H MVI B, 30H;loads register B with 30H ADD B ;A = 33H, ASCII code for 3 STA 8001H;display 3 on ASCII display 8085 Microprocessor - chintu.kay1986 - 08-16-2017 to get information about the topic "8085 microprocessor interfacing " full report ppt and related topic refer the page link bellow http://seminarsprojects.net/Thread-8085-microprocessor http://seminarsprojects.net/Thread-temperature-controller-using-8085-microprocessor |