|
; ----- EXAMPLE 8 ------- DATA TABLES --------------------------
JMP Start ; Skip past the data table.
DB 84 ; Data table begins.
DB C8 ; These values control the traffic lights
DB 31 ; This sequence is simplified.
DB 58 ; Last entry is also used as end marker
Start:
MOV BL,02 ; 02 is start address of data table
Rep:
MOV AL,[BL] ; Copy data from table to AL
OUT 01 ; Output from AL register to port 01
CMP AL,58 ; Last item in data table ???
JZ Start ; If yes then jump to Start
INC BL ; In no then point BL to the next entry
JMP Rep ; Jump back to do next table entry
END
; --------------------------------------------------------------
TASK
18) Improve the traffic lights data table so there is an
overlap with both sets of lights on red.
19) Use a data table to navigate the snake through the maze.
This is on port 04. Send FF to the snake to reset it.
Up, down left and right are controlled by the left four bits.
The right four bits control the distance moved.
20) Write a program to spin the stepper motor. Activate bits
1, 2, 4 and 8 in sequence to energise the electromagnets
in turn. The motor can be half stepped by turning on pairs
of magnets followed by a single magnet followed by a pair
and so on.
21) Use a data table to make the motor perform a complex sequence
of forward and reverse moves. This is the type of control
needed in robotic systems, printers and plotters. For this
exercise, it does not matter exactly what the motor does.
; --------------------------------------------------------------
| 
