The problem is like this: Each traffic light has green for 32 seconds and red for 48. From first to second traffic light a car needs 15 seconds from second to third 22 and from third to fourth 25.So second traffic light becomes green t1 seconds after the first traffic light turned green, the thir traffic light will become green t2 seconds after second etc Assume clock gen has 1 Hz freq. How can I implement it with SSI? Any hint to start this problem ps:im not posting any of my work because im not sure with what to start to be honest

 

Start by enumerating the distinct states required to fully realize the specification.

 

The problem is like this: Each traffic light has green for 32 seconds and red for 48. From first to second traffic light a car needs 15 seconds from second to third 22 and from third to fourth 25.So second traffic light becomes green t1 seconds after the first traffic light turned green, the thir traffic light will become green t2 seconds after second etc Assume clock gen has 1 Hz freq. How can I implement it with SSI? Any hint to start this problem ps:im not posting any of my work because im not sure with what to start to be honest

Start with a timing diagram of the lights.

 

Start with a timing diagram of the lights.

Did I misunderstand the problem?

To be honest, I have no idea what the acronym SSI stands for. I assume it means Synchronous State (something).

In that case, an exhaustive enumeration of all possible states should be the first step, no?

 

Did I misunderstand the problem?

To be honest, I have no idea what the acronym SSI stands for. I assume it means Synchronous State (something).

In that case, an exhaustive enumeration of all possible states should be the first step, no?

SSI -- Small Scale Integration. Usually refers to chips on the scale of fundamental gates, flip flops, and perhaps multiplexers. Not much more. The rule of thumb is about 10 or fewer logic gates. MSI -- Medium Scale Integration, is up to about 100 logic gates, includes things like shift registers, counters, decoders and similar scale circuits.

These actually describe the generational evolution of IC fabrication technology more than some conceptual logic distinction.

 

SSI -- Small Scale Integration.

Of course. Haven't seen the term used in about 30 years. And Google doesn't have a clue.

 

My other question still stands. Why not define the states first, and then define their relationships -- including the timing requirements?

 

My other question still stands. Why not define the states first, and then define their relationships -- including the timing requirements?

You can -- but the timing diagram of what you want to have happen is directly related to the problem statement and helps establish that you know what it is supposed to cause what. You really can't go defining states until you have a firm handle on what it is this state machine is supposed to accomplish. It also helps you see if there are any subtle things that can mess you up or that you might be able to leverage.

For most people that are comfortable designing state machines, starting with the state definitions is pretty natural because they've internalized the ability to do the first step. People new to this stuff usually haven't.

 

Of course. Haven't seen the term used in about 30 years. And Google doesn't have a clue.

It does, but you need to help it because it is swamped by the hits for Supplemental Security Income.

If you Google SSI electronics, you will probably get a link to Wikipedia's disambiguation page, which lists the appropriate term as one of the options.