Memory interfacing of microcontroller 8051

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Memory Interfacing with Microcontroller 8051
Dr. Nilesh Bhaskarrao Bahadure
July 25, 2021

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Introduction to Memory Interfacing
1Semiconductor Memory Fundamentals
2Memory Types
3Memory Structure and its requirements
4Memory Decoding
5Examples on Memory Interfacing

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Memory is simply a device that can be used to store the
information (data). The semiconductor memories are
extensively used because of their small size, low cost, high
speed, high reliability and ease of expansion of the memory
size, it consists mainly a ip ops one ip op can hold one bit
of data and some additional circuitry such as buers

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Semiconductor Memory

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Semiconductor Memory
In the design of all computers, semiconductor memories
are used as primary storage for data and code.
They are connected directly to the CPU and they are the
memory that the CPU asks for information (code or data).
Among the most widely used are RAM and ROM.Memory Capacity The number of bits that a semiconductor memory chip
can store is called its chip Capacity (bits or bytes)
Memory Organization

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Semiconductor Memory
Each memory chip contains 2N locations where N is the
number of address pins on the chip.
Each location contains M bits, where M is the number of
data pins on the chip.
The entire chip will contain 2N x M bits.Example: Memory organization of 4K x 4, 212 = 4096
locations, each location holding 4 Bits (so N=12 and
M=4)
Memory Speed (access time)

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Introduction to Memory Interfacing
1Semiconductor Memory Fundamentals
2Memory Types
3Memory Structure and its requirements
4Memory Decoding
5Examples on Memory Interfacing

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
ROM

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
ROM
1ROM (Read Only Memory)
ROM is the type of memory that does not lose its contents
when power is turned o. It is also called nonvolatile
memory.
2PROM (Programmable Memory)User programmable (one-time programmable) memory.If the information burned into PROM is wrong, it needs to
be discarded since internal fuses are blown permanently.
Special equipment needed: ROM burner or ROM
programmer.
3EPROM (Erasable Programmable ROM) 2,000 timesAllows making changes in the contents of PROM after it is
burned.
One can program the memory chip and erase it thousands
of times.
Erasing its contents can take up to 20 minutes; the entire
chip is erased.

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
ROM
All EPROM chips have a window that is used to shine
ultraviolet (UV) radiation to erase its contents.
Also referred to as UV-EPROM.
4EEPROM (Electrically Erasable ROM) 500,000 times
Method of erasure is electrical.Moreover, one can select which byte to be erased.Cost per bit is much higher than for UV-EPROM.5Flash Memory EPROMFirst, the process of erasure of the entire contents takes
less than a second, or one might say in a ash, hence its
name: ash memory.
When ash memory's contents are erased, the entire
device is erased.
Even though ash memories are writeable, like EPROM's
they nd their widest use in microcomputer systems for
storage of rmware.

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Random Access Memory

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Random Access Memory
1SRAM (Static RAM)
Storage cells are made of ip-ops and therefore they do
not require refreshing to keep their data.
A cell handling one bit requires 6 or 4 transistors each,
which is too many.
SRAMS are widely used for cache memory and
battery-backed memory systems.
2DRAM (Dynamic RAM)Uses MOS capacitors to store a bitRequires constant refreshing due to leakage (every 2ms {
4ms).

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Random Access Memory
Advantages
a. High density (capacity),
b. Cheaper cost per bit
c. Lower power consumption.
Disadvantage
a. While it is being refreshed, data cannot be accessed
b. Larger access times
c. Too many pins due to large capacity

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Memory Device

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Introduction to Memory Interfacing
1Semiconductor Memory Fundamentals
2Memory Types
3Memory Structure and its requirements
4Memory Decoding
5Examples on Memory Interfacing

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Memory structure of RAM and ROM

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Basic Concept of Memory Interfacing
The memory interfacing requires:
Select the chip (Enable CS).Identify the register.Enable the appropriate buer ( Read or Write)Microcontroller based system include memory devices and the
input { output devices. It is important to note that
microcontroller can communicate (Read or Write) with only
one device at a time, since the address, data and control lines
are common for all the devices.
In order to communicate with memory or IO device, it is
necessary to decode the address from the microcontroller.

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Introduction to Memory Interfacing
1Semiconductor Memory Fundamentals
2Memory Types
3Memory Structure and its requirements
4Memory Decoding
5Examples on Memory Interfacing

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Absolute or Full Decoding

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Partial or Linear Decoding

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Introduction to Memory Interfacing
1Semiconductor Memory Fundamentals
2Memory Types
3Memory Structure and its requirements
4Memory Decoding
5Examples on Memory Interfacing

Memory
Interfacing
with Micro-
controller
8051
Dr. Nilesh
Bhaskarrao
Bahadure
Semiconductor
Memory
Fundamentals
Memory Types
Memory
Structure and
its
requirements
Memory
Decoding
Examples on
Memory
Interfacing
Example
1
Show the interfacing of an 8051 microcontroller with 8K bytes
of data ROM.
Answer
1