8051-ROM-Read
This project shows the memory read operation in 8051. In this circuit the
contents of the memory location from 0000 to 000F is read and the value
displayed in the 7-Segment Display.
The circuit contains an 8051 chip, 7-Segment displays, Latch, Binary to 7-Segment
Decoder and 128K x 8-Bit CMOS One Time PROM. Ports P0 and P2 of 8051 are used
for memory addressing while Port P1 is used as the output port.
The address of memory is send to PROM via latch from the address lines of 8051.
The contents of this location are read and send to the data lines. This data
appears at the output in
7-segment form.
The
code editor window
contains the source code written in either C or assembly
language.
The program is as shown:
mov r0,#0x10 ; R0 is loaded with hex value ‘10’
mov dptr,#0x000 ; Data Pointer is loaded with ‘0000’
$100:
movx a,@dptr ; Content of external memory location pointed by the data
pointer is copied to accumulator
mov p1,a ; Accumulator content is copied to Port P1, which is connected to
the display device
mov r1,#0x0ff ; R1 is loaded with hex value ‘FF’
$200:
djnz r1,$200 ; Decrement R1 and check whether it is equal to zero. If not,
jump to label ‘$200’
inc dptr ; Increment Data Pointer
djnz r0,$100 ; Decrement R0 and check whether it is equal to zero. If not,
jump to label ‘$100’
The source code in the
code editor window
has to be
compiled
after making any modifications
(editing).
Also the code can be
debugged
during
simulation.
