MEMORY INTERFACING OF Of 8051/8031 MICROCONTROLLER

Q.) An 8031 microcontroller based system requires 8kb program memory and 8kb external data memory. Also it requires 8279 for keyboard/display interface and 8255 for additional I/O ports. Develop a schematic to interface the memories, 8279 and 8255 to 8031 microcontroller, and allocate addresses to all the devices.

•    The 8kb program memory can be provided by using one number of 8kb EPROM 2764. The 8kb EPROM require 13 address lines and so the address lines A0 – A12 are connected to EPROM address pins to select its internal locations.

•    The remaining address lines A13, A14 and A15 are logically ORed and used as chip select signal for EPROM.

•    The signal PSEN(low) is used as read control signal for EPROM and so the EPROM can be accessed only as program memory. Here the EPROM is mapped in the first 8kb of program memory address space with address range 0000H to 1FFFH. (Here the remaining 56kb program memory address space is not utilized).

•    The 8031 provide a separate 64kb external data memory address space.

•    The RAM memory, 8279 and 8255 can be interfaced to 8031 as data memory

•    The 8kb RAM can be provided by using one number of 8kb RAM 6264. The 8kb RAM requires 13 address lines and so the address lines A0 – A12 are connected to address pins of RAM to select its internal location.

•    The 8255 require two address lines to select its internal devices port-A, port-B, port-C and control register. Hence the address lines A0 and A1 of controller are connected to A0 and A1 of 8255 respectively.

•    The 8279 require one address line to select its data register and control register. Hence the address line A0 of 8031 is connected to A0 of 8279.

•    A 2-to-4 decoder is employed in the system to generate the chip select signals required for the RAM, 8255 and 8279. The address lines A13 and A14 are connected to input of decoder to generate four chip select signals. The address line A15 is used as logic low chip enable for decoder.

•    In 8031 based system, the pin of 8031 is permanently grounded.

•    The 8031 provides separate read and write control signals RD(low) and WR(low) for reading and writing with devices interfaced as data memory.

•    The 8031 has a separate 256 bytes internal data memory address space allotted to internal RAM and SFR.




Address allocation for interfacing of 8031

Q.) An 8051 microcontroller based systems require 32 kb program memory and 16kb data memory. The system should also utilize the internal 4kb RAM. Also the system should include a keyboard/display controller 8279 and an 8255 I/O port device. Draw the interface diagram and allocate addresses to memory and I/O devices.

•    The 8051 has 4kb internal ROM which is mapped in the beginning of program memory address space with address in the range 0000H to 0FFFH.

•    Hence for a total requirement of 32kb, we have to provide 28kb external memory. Therefore one number 32kb EPROM 27256 can be interfaced to microcontroller in which the first 4kb will not be accessed by the controller if pin EA(low) is tied to Vcc or +5V.

•    The 32kb EPROM require 15 address lines and so the address lines A0 to A14 are connected to the address pins of EPROM to select its internal locations.

•    The address line A15 is used as chip s signal.

•    The EPROM is selected for program memory addresses when A0 = 0.

•    The signal PSEN(low) is used as read control signal for EPROM and so the EPROM can be
             accessed only as program memory.   

•    The 16kb RAM memory can be implemented by using two numbers of 8kb RAM 6264.

•    The RAM memories, 8255 and 8279 can be interfaced to 8051 controllers as data memory.

•    The 8kb RAM require 13 address lines and so the address lines A0 – A12 are connected to address pins of RAM to select its internal locations.

•    The address line A0 and A1 are connected to 8255 and the address line A0 is connected to 8279 to select their internal devices.

•    A 2-to-4 decoder is employed in the system to generate the chip select signals required for RAM, 8255 and 8279. The address lines A13 and A14 are connected to input of decoder to generate four chip select signals. The address line A15 is used as logic low chip enable for decoder.

•    Since the internal ROM is used in the system, the pin EA(low) should be tied to Vcc or +5V.

•    The 8051 provides separate read and write control signals RD(low) and WR(low) for reading and writing with devices interfaced as data memory.

•    The 8051 has a separate 256 bytes internal data memory address space allotted to internal RAM and SFR.








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PROJECTS 8086 PIN CONFIGURATION 80X86 PROCESSORS TRANSDUCERS 8086 – ARCHITECTURE Hall-Effect Transducers INTEL 8085 OPTICAL MATERIALS BIPOLAR TRANSISTORS INTEL 8255 Optoelectronic Devices Thermistors thevenin's theorem MAXIMUM MODE CONFIGURATION OF 8086 SYSTEM ASSEMBLY LANGUAGE PROGRAMME OF 80X86 PROCESSORS POWER PLANT ENGINEERING PRIME MOVERS 8279 with 8085 MINIMUM MODE CONFIGURATION OF 8086 SYSTEM MISCELLANEOUS DEVICES MODERN ENGINEERING MATERIALS 8085 Processor- Q and A-1 BASIC CONCEPTS OF FLUID MECHANICS OSCILLATORS 8085 Processor- Q and A-2 Features of 8086 PUMPS AND TURBINES 8031/8051 MICROCONTROLLER Chemfet Transducers DIODES FIRST LAW OF THERMODYNAMICS METHOD OF STATEMENTS 8279 with 8086 HIGH VOLTAGE ENGINEERING OVERVOLATGES AND INSULATION COORDINATION Thermocouples 8251A to 8086 ARCHITECTURE OF 8031/8051 Angle-Beam Transducers DATA TRANSFER INSTRUCTIONS IN 8051/8031 INSTRUCTION SET FOR 8051/8031 INTEL 8279 KEYBOARD AND DISPLAY INTERFACES USING 8279 LOGICAL INSTRUCTIONS FOR 8051/8031 Photonic Transducers TECHNOLOGICAL TIPS THREE POINT STARTER 8257 with 8085 ARITHMETIC INSTRUCTIONS IN 8051/8031 LIGHTNING PHENOMENA Photoelectric Detectors Physical Strain Gage Transducers 8259 PROCESSOR APPLICATIONS OF HALL EFFECT BRANCHING INSTRUCTIONS FOR 8051/8031 CPU OF 8031/8051 Capacitive Transducers DECODER Electromagnetic Transducer Hall voltage INTEL 8051 MICROCONTROLLER INTEL 8251A Insulation Resistance Test PINS AND SIGNALS OF 8031/8051 Physical Transducers Resistive Transducer STARTERS Thermocouple Vacuum Gages USART-INTEL 8251A APPLICATIONs OF 8085 MICROPROCESSOR CAPACITANCE Data Transfer Instructions In 8086 Processors EARTH FAULT RELAY ELECTRIC MOTORS ELECTRICAL AND ELECTRONIC INSTRUMENTS ELECTRICAL BREAKDOWN IN GASES FIELD EFFECT TRANSISTOR (FET) INTEL 8257 IONIZATION AND DECAY PROCESSES Inductive Transducers Microprocessor and Microcontroller OVER CURRENT RELAY OVER CURRENT RELAY TESTING METHODS PhotoConductive Detectors PhotoVoltaic Detectors Registers Of 8051/8031 Microcontroller Testing Methods ADC INTERFACE AMPLIFIERS APPLICATIONS OF 8259 EARTH ELECTRODE RESISTANCE MEASUREMENT TESTING METHODS EARTH FAULT RELAY TESTING METHODS Electricity Ferrodynamic Wattmeter Fiber-Optic Transducers IC TESTER IC TESTER part-2 INTERRUPTS Intravascular imaging transducer LIGHTNING ARRESTERS MEASUREMENT SYSTEM Mechanical imaging transducers Mesh Current-2 Millman's Theorem NEGATIVE FEEDBACK Norton's Polarity Test Potentiometric transducers Ratio Test SERIAL DATA COMMUNICATION SFR OF 8051/8031 SOLIDS AND LIQUIDS Speed Control System 8085 Stepper Motor Control System Winding Resistance Test 20 MVA 6-digits 6-digits 7-segment LEDs 7-segment A-to-D A/D ADC ADVANTAGES OF CORONA ALTERNATOR BY POTIER & ASA METHOD ANALOG TO DIGITAL CONVERTER AUXILIARY TRANSFORMER AUXILIARY TRANSFORMER TESTING AUXILIARY TRANSFORMER TESTING METHODS Analog Devices A–D BERNOULLI’S PRINCIPLE BUS BAR BUS BAR TESTING Basic measuring circuits Bernoulli's Equation Bit Manipulation Instruction Buchholz relay test CORONA POWER LOSS CURRENT TRANSFORMER CURRENT TRANSFORMER TESTING Contact resistance test Current to voltage converter DAC INTERFACE DESCRIBE MULTIPLY-EXCITED Digital Storage Oscilloscope Display Driver Circuit E PROMER ELPLUS NT-111 EPROM AND STATIC RAM EXCITED MAGNETIC FIELD Electrical Machines II- Exp NO.1 Energy Meters FACTORS AFFECTING CORONA FLIP FLOPS Fluid Dynamics and Bernoulli's Equation Fluorescence Chemical Transducers Foil Strain Gages HALL EFFECT HIGH VOLTAGE ENGG HV test HYSTERESIS MOTOR Hall co-efficient Hall voltage and Hall Co-efficient High Voltage Insulator Coating Hot-wire anemometer How to Read a Capacitor? 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