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8051 INTERFACING                          WITH EXTERNAL                          MEMORYPRESENTED BY-PRIYA SRIVASTAVA      ...
S E MI C O N D U C T O R ME MO R Y In the design of all microprocessor-based  systems, semiconductor memories are used as...
ME MO R Y C A P A C I T Y The no. of bits that a semiconductor memory  chip can store is called chip capacity. It can be...
ME MO R YORGANI S ATI ON          A memory chip contains 2 to           the power n, locations, where           n is the ...
SPEED One of the most important characteristics of a  memory chip is the speed at which its data can  be accessed. To ac...
M e mo r y ma p p e d I O 8051 Memory and ports assigned the addresses such each have distinct range of addresses in th...
H a r v a r d M e mo r yAr c h i t e c t u r e Two sets of memory─ program memory and data memory. Two control signals─...
R O M (R E A D O N L Y M E M O R Y ) ROM is a type of memory that does not lose its  contents when the power is turned of...
EXT ERNAL RAM External RAM is any random access memory which  is found off-chip. Since the memory is off-chip it is not ...
E X T E R N A L M E M O R Y WH E NCONT ROL S I GNAL E AI NACT I VE Then processor always accesses the external memory wh...
CONT ROL S I GNAL E A When a control signal EA activate ─ processor always accesses the external addresses in memory in...
Microcontroller
Microcontroller
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Microcontroller

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This ppt is based on interfacing of 8051 microcontroller with external memory.

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Transcript of "Microcontroller"

  1. 1. 8051 INTERFACING WITH EXTERNAL MEMORYPRESENTED BY-PRIYA SRIVASTAVA PRESENTED BY:-090105801E.I, III Yr. SRIVASTAVA PRIYA 090105801 E.I, III yr.
  2. 2. S E MI C O N D U C T O R ME MO R Y In the design of all microprocessor-based systems, semiconductor memories are used as primary storage for code & data. Semiconductor memories are connected directly to the CPU first asks for information. For this reason, semiconductors memories are sometimes referred to as primary memory. The most widely used are ROM & RAM.
  3. 3. ME MO R Y C A P A C I T Y The no. of bits that a semiconductor memory chip can store is called chip capacity. It can be in units of Kbits, Mbits, and so on. While the memory capacity of a memory IC chip is always given in bits, the memory capacity of a computer system is given in bytes.
  4. 4. ME MO R YORGANI S ATI ON  A memory chip contains 2 to the power n, locations, where n is the no. of address pins.  Each location contains m bits, where m is the no. of data pins on the chip.  The entire chip will contain 2 to the power n * m bits.
  5. 5. SPEED One of the most important characteristics of a memory chip is the speed at which its data can be accessed. To access the data, the address is presented to the address pins, the READ pin is activated, and after a certain amount of time elapsed, the data shows up at the data pins. The shorter this elapsed time, the better, and consequently, the more expensive the memory chip. The speed of the memory chip is commonly referred to as its access time.
  6. 6. M e mo r y ma p p e d I O 8051 Memory and ports assigned the addresses such each have distinct range of addresses in the data memory address space. Interfacing circuit design identical to that for the memory connects the external ports and programmable peripheral interface (PPI).
  7. 7. H a r v a r d M e mo r yAr c h i t e c t u r e Two sets of memory─ program memory and data memory. Two control signals─ PSEN and RD to control read from program memory or data memory. Control signal ALE to control use of AD0- AD7 as address or data at a given instance
  8. 8. R O M (R E A D O N L Y M E M O R Y ) ROM is a type of memory that does not lose its contents when the power is turned off; thats why it is also called as nonvolatile memory. There are different types of ROM, such as PROM, EPROM, EEPROM, Flash EPROM, and mask ROM.
  9. 9. EXT ERNAL RAM External RAM is any random access memory which is found off-chip. Since the memory is off-chip it is not as flexible in terms of accessing, and is also slower . For example, to increment an Internal RAM location by 1 requires only 1 instruction and 1 instruction cycle. To increment a 1-byte value stored in External RAM requires 4 instructions and 7 instruction cycles. In this case, external memory is 7 times slower! What External RAM loses in speed and flexibility it gains in quantity. While Internal RAM is limited to
  10. 10. E X T E R N A L M E M O R Y WH E NCONT ROL S I GNAL E AI NACT I VE Then processor always accesses the external memory whether EA active or not . Internal RAM and SFR addresses between 0x00 and 0xFF are same as external data memory addresses 0x0000 and 0xFFFF. Internal program memory addresses between 0x0000 to 0xFFF (in case of 4 kB internal ROM) are same as external program memory addresses 0x0000 and 0xFFFF.
  11. 11. CONT ROL S I GNAL E A When a control signal EA activate ─ processor always accesses the external addresses in memory instead of internal memory or register addresses. To indicate the program code is stored in external ROM, this pin must be connected to GND. This is the case for the 8051-based system.
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