# T junction traffic light project

#### ci139

Joined Jul 11, 2016
1,898
your cycle length is 18 seconds think of 2/6-bit (one/3 color) PROM with 18 addressable memory locations (incase of PROM you can have input translation Combinational logic - Wikipedia)

#### dl324

Joined Mar 30, 2015
16,898
well the main road lights can be considered as one traffic light.
so there are two sets - main and side. in total 6 lights
Exactly, I should have been more precise. There are 6 unique lights that need to be controlled; obviously.

Have you made any progress on this? Showing what you derived is controlling and how you derived it will help us guide you.

#### RBR1317

Joined Nov 13, 2010
714
Rearranging the positions of the traffic lights suggests a simple pattern that can be represented by a 3-bit counter with the counting sequence: 010, 011, 000, 111, 110, 101, ... repeating.

The LSB establishes the base timing interval of 3 seconds. The middle bit drives the green-yellow pattern. The MSB switches from the main to side street and drives the red lights.

Note: The 3-bit counter can be designed with 3 JK flip-flops and 3 gates.

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#### dl324

Joined Mar 30, 2015
16,898
Rearranging the positions of the traffic lights suggests a simple pattern that can be represented by a 3-bit counter with the counting sequence: 010, 011, 000, 111, 110, 101, ... repeating.

The LSB establishes the base timing interval of 3 seconds. The middle bit drives the green-yellow pattern. The MSB switches from the main to side street and drives the red lights.

Note: The 3-bit counter can be designed with 3 JK flip-flops and 3 gates.
This is homework. We're supposed to guide the member, not do the work for them.

The OP still hasn't decided how many counters he should use and wouldn't reveal what the decoder logic was driving or how it was derived.
i don't fully understand if i need one or two counters...
I've managed to produce a 5 sec up 1 sec down output for the upper counter
and 2 sec up 1 sec down output for the lower counter

I want to use some kind of flip flops to control the output signal.

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#### ericgibbs

Joined Jan 29, 2010
18,830
hi,
As this Thread is in the Homework Forum, please do not give complete answers to the TS assignment, only hints and guidance to the TS.

Mod.

#### RBR1317

Joined Nov 13, 2010
714
It was hardly a complete answer; more like an initial Preliminary Design Review where engineering concepts are discussed to better understand the problem before any actual design work is done.

#### ci139

Joined Jul 11, 2016
1,898
It was hardly a complete answer;
(no matter the TS may already have found something else interesting to do) your color box below does not make any sense ? you should only plot one side light there - but you have 1-st half cycles for each ? -- making this incomplete reference . . . if it was intended so - it applies not giving the full answers - but may be confusing for a novice
don't fully understand if i need one or two counters...
it depends how you set up your automaton . . . if you use "decoders" 1 will do if you want to "divide" your clock for/from 6$$\rightarrow$$4 cycles you need two or three - again - depending on how you set such up

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