Hi everyone, I'm involved in the design project for controling pedestrians crossing a road.
SPECIFICATIONS:
-The use of programmable devices is not allowed.
-The timing cct must drive two Red-Green LEDs as display devices.
-The Green LED must be on for 8 seconds(constant light) and a seven-segment do a count down form 8 seconds to 0 seconds displaying the walk time.
-In addition the Green LED must also flash for the next 4 seconds
-The Red LED must be on for rest of the time divisions.
TIME DIVISION:
1. The Red LED must be on for 44 seconds(seven-segment must be off).
2. The Green LED must be on(constant light) for 8 seconds + seven-segment
3. The Green LED must flash for 4 seconds(seven-segment must be off)
4. The Red LED must be on for the last 4 seconds(seven-segment must be off)
-The sequence start at number 1 and ends at number 4.
FIRST APPROACH:
-I've noticed that the lighting pettern is sequetial in nature(Red 44 s,Green 8 s + seven-segment,Green flashing 4 s,Red 4 s), so ive used a dacade counter to give the cct this property
-I've also noticed that the operation time interval is 60 seconds.
PLAN:
-My plan was to actually produce a time delay of 60 seconds and divide this total time interval into the required time intervals(44s,8s,4s,4s)
-I was planing on using a 555 timer to produce the time delay of 60 seconds and use its output to clock the dacade counter. The outputs counter are used to divide the 60 seconds to the required time intervals, but the timer is capable of producing long time delays(my simulation works for high frequencies but I get a simulation error for low frequencies)
-The Red LED is on for binary 1 of the counter to binary 4.
-Since the Green LED is recieving two different signals, constant signal(for producing constant light) and a oscillating signal(for producing flashing light), I've use an OR-gate to differentiate between the two different signals and the up/down counter(operating at down mode) is connected to the input of the OR-gate with constant signal and to its clock via an AND-gate so that when the constant signal is recieved the up/down counter is triggered and the seven-segment displays a down count from 8 to 0.
-The Green LED is on for binary 5 to 7 (constant light) + seven-segment.
-The Green LED is flashing for binary 8.
-The Red is on for binary 9.
Can anyone help in getting the time divisions right
SPECIFICATIONS:
-The use of programmable devices is not allowed.
-The timing cct must drive two Red-Green LEDs as display devices.
-The Green LED must be on for 8 seconds(constant light) and a seven-segment do a count down form 8 seconds to 0 seconds displaying the walk time.
-In addition the Green LED must also flash for the next 4 seconds
-The Red LED must be on for rest of the time divisions.
TIME DIVISION:
1. The Red LED must be on for 44 seconds(seven-segment must be off).
2. The Green LED must be on(constant light) for 8 seconds + seven-segment
3. The Green LED must flash for 4 seconds(seven-segment must be off)
4. The Red LED must be on for the last 4 seconds(seven-segment must be off)
-The sequence start at number 1 and ends at number 4.
FIRST APPROACH:
-I've noticed that the lighting pettern is sequetial in nature(Red 44 s,Green 8 s + seven-segment,Green flashing 4 s,Red 4 s), so ive used a dacade counter to give the cct this property
-I've also noticed that the operation time interval is 60 seconds.
PLAN:
-My plan was to actually produce a time delay of 60 seconds and divide this total time interval into the required time intervals(44s,8s,4s,4s)
-I was planing on using a 555 timer to produce the time delay of 60 seconds and use its output to clock the dacade counter. The outputs counter are used to divide the 60 seconds to the required time intervals, but the timer is capable of producing long time delays(my simulation works for high frequencies but I get a simulation error for low frequencies)
-The Red LED is on for binary 1 of the counter to binary 4.
-Since the Green LED is recieving two different signals, constant signal(for producing constant light) and a oscillating signal(for producing flashing light), I've use an OR-gate to differentiate between the two different signals and the up/down counter(operating at down mode) is connected to the input of the OR-gate with constant signal and to its clock via an AND-gate so that when the constant signal is recieved the up/down counter is triggered and the seven-segment displays a down count from 8 to 0.
-The Green LED is on for binary 5 to 7 (constant light) + seven-segment.
-The Green LED is flashing for binary 8.
-The Red is on for binary 9.
Can anyone help in getting the time divisions right
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