Form Past to the Future! Retro to Cyber! Fun to Serius Stuff ! All in One: Assembly Language : 8086 Assembler Tutorial Part 12

Assembly Language programming : 8086 Assembler Tutorial (Part 12)

Controlling External Devices

There are 3 devices attached to the emulator: Traffic Lights, Stepper-Motor and Robot. You can view devices using "Virtual Devices" menu of the emulator.

For technical information see I/O ports section of Emu8086 reference.

In general, it is possible to use any x86 family CPU to control all kind of devices, the difference maybe in base I/O port number, this can be altered using some tricky electronic equipment. Usually the ".bin" file is written into the Read Only Memory (ROM) chip, the system reads program from that chip, loads it in RAM module and runs the program. This principle is used for many modern devices such as micro-wave ovens and etc...

Traffic Lights

Usually to control the traffic lights an array (table) of values is used. In certain periods of time the value is read from the array and sent to a port. For example:


; directive to create BIN file:
#MAKE_BIN#
#CS=500#
#DS=500#
#SS=500#
#SP=FFFF#
#IP=0#

; skip the data table:
JMP start

table DW 100001100001b
      DW 110011110011b
      DW 001100001100b
      DW 011110011110b

start:

MOV SI, 0

; set loop counter to number
; of elements in table:
MOV CX, 4

next_value:

; get value from table:
MOV AX, table[SI]

; set value to I/O port
; of traffic lights:
OUT 4, AX

; next word:
ADD SI, 2

CALL PAUSE

LOOP next_value

; start from over from
; the first value
JMP start

; ==========================
PAUSE PROC
; store registers:
PUSH CX
PUSH DX
PUSH AX

; set interval (1 million
; microseconds - 1 second):
MOV     CX, 0Fh
MOV     DX, 4240h
MOV     AH, 86h
INT     15h

; restore registers:
POP AX
POP DX
POP CX
RET
PAUSE ENDP
; ==========================

Stepper-Motor

The motor can be half stepped by turning on pair of magnets, followed by a single and so on.

The motor can be full stepped by turning on pair of magnets, followed by another pair of magnets and in the end followed by a single magnet and so on. The best way to make full step is to make two half steps.

Half step is equal to 11.25 degrees.
Full step is equal to 22.5 degrees.

The motor can be turned both clock-wise and counter-clock-wise.

See stepper_motor.asm in Samples folder.

See also I/O ports section of Emu8086 reference.

Robot

Complete list of robot instruction set is given in I/O ports section of Emu8086 reference.

To control the robot a complex algorithm should be used to achieve maximum efficiency. The simplest, yet very inefficient, is random moving algorithm, see robot.asm in Samples folder.

It is also possible to use a data table (just like for Traffic Lights), this can be good if robot always works in the same surroundings.

emu8086 is better than NASM, MASM or TASM

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Form Past to the Future! Retro to Cyber! Fun to Serius Stuff ! All in One

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Sunday 30 July 2017

Assembly Language : 8086 Assembler Tutorial Part 12

emu8086 is better than NASM, MASM or TASM

My Paypal Account is : ksw.industries@gmail.com

___________________________________________

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