EC4205 Microprocessor and Microcontroller

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1 EC4205 Microprocessor and Microcontroller Webcast link: All announcement made through webpage: check back often Students are welcome outside the class (right after class) Dr. A. Islam Dept. of ECE BIT, Mesra, Ranchi Prepared and presented by Dr. A. Islam 1

2 EC4205 Lecture notes based on material From me, Prof. (Dr.) R. Sukesh Kumar and following text books: 1. Digital Computer Electronics, 2/e, by A. P. Malvino. 2. Microprocessor Architecture, Programming and Applications with 8085, by R. S. Gaonkar. 3. Microprocessor and Interfacing, Programming of Hardware, by D. Hall. 4. Microprocessor and Peripherals, by S. P. Chowdhury and S. Chowdhury. 5. INTEL 8086/8088 Microprocessor, Architecture, Programming, Design and Interfacing, 3/e, by B. S. Chhabra. 6. Microprocessor, Microcomputer and their Applications, 2/e, by A, K. Mukhopadhyay. 7. The Intel Microprocessors 8086/888, 80186/80188, 80286, 80386, 80486, Pentium and Pentium Pro processor architecture, programming and interfacing, 4/e, by B. B. Brey. 8. Microprocessors with applications in process control, by SI Ahson. 9. Microprocessors theory and applications: Intel and Motorola, by M. Rafiquzzaman. Use the material without violating copyright act involved with original books. Prepared and presented by Dr. A. Islam 2

3 Module-I: Outline 1. Revision of logic circuits with emphasis on control lines 2. SAP concepts with stress on timing diagrams 3. Microinstructions 4. Microprogramming 5. Variable machine cycle 6. Architecture of 8085 Processor 7. Functions of all signals 8. Bus concepts 9. Multiplexed and De-multiplexed Bus 10.Minimum system Prepared and presented by Dr. A. Islam 3

4 Prepared and presented by Dr. A. Islam 4

5 IO/Mbar, S 0, S 1 become valid at the beginning of a machine cycle and remain stable through out the cycle. The falling edge of ALE may be used to latch the state of these lines. Prepared and presented by Dr. A. Islam 5

6 1. Typical memory map: Generally ROM is mapped at lower memory area because PC begins at 0000H and stack grows towards lower memory. 2. Next comes the RAM or variable data area generally pointed to by HL pair. 3. Highest part of the memory is generally used for stack. Fig. 13.9(Malvino) Typical memory map Prepared and presented by Dr. A. Islam 6

7 RST 5.5 can interrupt an RST 7.5 ISR if the interrupts are re-enabled before the end of the RST 7.5 ISR. TRAP interrupt must go high and remain high until it is acknowledged. It will not be recognized again until it goes low, then high again. Prepared and presented by Dr. A. Islam 7

8 Pin 1 & 2: X1 & X2 (i/p): The 8085 has an on-chip oscillator with all the required circuitry except for the crystal, parallel-resonant LC circuit (i. e., LC tank), or RC network that controls the frequency. Driving frequency must be at least 1MHz (because 8085A can work from 500 KHz to MHz 8085A-2 can work up to 5 MHz and hence the crystal frequency must be twice the desired internal clock frequency. That is 8085A-2 can be operated with a 10 MHz crystal (for 5 MHz clock). Processor s internal flip-flop divides the crystal or external clock frequency by 2 to give processor s internal operating frequency. The external clock may not provide perfect square wave with 50% duty cycle as shown above (CLK). But the 8085 will be able to generate perfect square wave with 50% duty cycle with its internal JK (its J & K are tied to V DD ) flip-flop at its Q and Qbar as shown above. Prepared and presented by Dr. A. Islam 8

9 For driving frequencies up to and including 6 MHz an external clock signal can be connected to X1 leaving X2 open-circuited as shown in Fig. D. 1-6 (Manual). If the driving frequency is from 6 MHz to 10 MHz, stability of the clock generator will be improved by driving both X1 and X2 with push-pull source as shown in Fig. E. 1-10(manual). Note in Fig. D and E that pullup resistors are required to assure that the high voltage level of the input is at least 4 V. Processor s internal flip-flop divides the crystal frequency by 2 to give processor s internal operating frequency. Prepared and presented by Dr. A. Islam 9

EC4205 Microprocessor and Microcontroller

EC4205 Microprocessor and Microcontroller Webcast link: https://sites.google.com/a/bitmesra.ac.in/aminulislam/home All announcement made through webpage: check back often Students are welcome outside the