Bahasa Assembler :
Control External Device
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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.
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