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Level 6

The customer TrafficControl Inc. wants you to create a new control mechanism for their pedestrian traffic lights.

Specification

• On start the traffic light needs to be red.
• When a pedestrian presses a button a display shall count down from 10 to 0
• When the timer reaches zero the traffic light goes from red to red-yellow to green
• After some seconds the traffic light goes back to yellow and then to red

Help

Cable connections

• MCU1-P0 -> Button1
• MCU1-P1 -> Red LED
• MCU1-X0 -> Display
• MCU1-X1 -> MCU2-X0
• MCU1-P0 -> Green LED
• MCU1-P1 -> Yellow LED

Hints

• MCU2 should control the green and yellow LEDs when MCU1 sends an XBus signal
• MCU1 displays the countdown in a loop and then sends the signal to MCU2
• After sending the signal MCU1 waits for an XBus signal from MCU2 to switch back to red

Solution

MCU1

start:
mov 100 p1
teq p0 100
- jmp start
mov 10 acc
loop:
sub 1
mov acc x0
slp 4
tgt acc 0
+ jmp loop
mov 1 x1
slp 4
mov 0 p1
mov x1 dat

MCU2

teq x0 1
+ mov 100 p1
+ slp 5
+ mov 0 p1
+ mov 100 p0
+ slp 30
+ mov 0 p0
+ mov 100 p1
+ slp 5
+ mov 0 p1
+ mov 0 x0