8051-RAM-Sort

This 8051 project shows the sorting (both ascending and descending) of numbers stored in the RAM. To simulate circuit in this project, initially activate Mixed Mode simulator from the Schematic Editor window. Simulation can be performed by selecting Run Transient analysis (Oscillograph) from Simulation menu.

The circuit contains an 8051 chip, Binary to 7 Segment Decoder, Seven Segment LED Display, Buffer register and 32K x 8-Bit CMOS Static RAM (TC55257). In this circuit, Port P0 is used for memory addressing. The status of P2.7 is set to ‘1’ to enable sorting in ascending mode and set to ‘0’ to enable descending mode.

The address of memory isThe address of memory is send to RAM via latch from the address lines of 8051. At any instant, the contents of two memory locations are compared. The mode of sorting (ascending or descending) depends on the status of P2.7. During sorting, the contents of successive memory locations may be exchanged. The number of memory locations to be compared and the number of comparisons to be carried out are specified in the code. For each comparison, the data pointer is incremented so as to point to the next memory location. The sorted sequence of numbers will be stored in RAM after the required number of comparisons. This number sequence will be displayed in 7-segment form at the output.

The source code written either in C or Assembly language can be viewed from the code editor window program is as shown

_main:

mov r0,#0x0f ; R0 is loaded with value ‘15’

$300:

mov r1,#0x0f ; R1 is loaded with value ‘15’

mov b,#0x00 ; Register B is loaded with ‘00’

mov dptr,#0x000 ; Data pointer is loaded with value ‘0000’

$200:

movx a,@dptr ; The content of the address location as indicated by data pointer is copied to Accumulator

xch a,b ; Exchange the contents of accumulator and register B

inc dptr ; Increment Data Pointer

movx a,@dptr ; The content of the next address location as indicated by data pointer is copied to Accumulator

anl p2,#0x80 ; Logically AND the value at Port P2 with value’80’

mov r7,p2 ; The result of AND operation is copied from Port P2 to R7

cjne r7,#0x80,loop ; Check whether the value in R7 is equal to ‘80’. If not, jump to loop

loop3:

cjne a,b,loop2 ; Check whether the content of Accumulator and register B are equal. If not, jump to loop2

loop2:

jnc $100 ; Check whether Accumulator content is less than the data in register B. If not, jump to label $100

sjmp skip ; Jump to loop skip

loop:

cjne a,b,loop1 ; Check whether the content of Accumulator and register B are equal. If not, jump to loop1

loop1:

jc $100 ; Check whether Accumulator content is less than the data in register B. If yes, jump to label $100

skip:

dec dpl ; Decrement Data Pointer

movx @dptr,a ; Move the content of Accumulator to the address location indicated by Data Pointer

inc dptr ; Increment Data Pointer

xch a,b ; Exchange the contents of accumulator and register B

movx @dptr,a ; Move the content of Accumulator to the address location indicated by Data Pointer

$100:

djnz r1,$200 ; Check whether R1 is zero. If not jump to label $200

djnz r0,$300 ; Check whether R0 is zero. If not jump to label $200

mov r2,#0x10 ; R2 is loaded with value ‘10’

mov p1,#0x00 ; The value ‘00’ is loaded to Port P1

mov dptr,#0x000 ; Data pointer is loaded with value ‘0000’

$400:

movx a,@dptr ; The content of the address location as indicated by data pointer is copied to Accumulator

mov p1,a ; Accumulator content is copied to Port P1

mov r3,#0x5 ; R3 is loaded with value ‘50’

$500:

djnz r3,$500 ; Check whether R3 is zero. If not jump to label $500

inc dptr ; Increment Data Pointer

djnz r2,$400 ; Check whether R2 is zero. If not jump to label $400

00101$:

ret ; Return

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.