You are working with a company who invented a new battery technology that allows ultra-fast charging. Unfortunately, the new batteries have the tendency to overheat while charging. The company has already installed a digital temperature monitor that turns the charging off completely once the temperature exceeds a certain threshold.

Now, you are asked to develop a controller which adds some “intelligence” to the charger: Rather than shutting charging off completely after the safe temperature limit is exceeded, the controller should turn charging on again if the temperature drops. However, after the temperature has been exceeded three times in a row, charging should stop permanently and only a manual reset will bring the charger out of its safety lockdown.

You are given two digital signals as inputs: The temperature sensor signal “Temp” and a “Start_charging” signal. The temperature sensor signal is 0 as long as the temperature is below the safe threshold and 1 above. A logic 1 at the “Start Charging” input should turn the charger on, a 0 off. Your controller is supposed to have two outputs: “Charge_on” and “OT_error”. Charge_on should be 1 when the charger is on and OT error should be 1 when the safety lockdown is active.

Deliverables

• You need to design two finite state synchronous machines.
• One design must be a Moore design, the other a Mealy design.
• You should comment on why your controller adds value from multiple perspectives (technological, societal, financial, environmental, etc.). One or two sentences is sufficient.
• The number of states is not defined, you can use as little or as many as you need to provide the desired functionality.
• If something is not clearly documented in the summary, you need to make assumptions. The assumptions need to be documented.
• Please remember that you can design the state machines and add functionality to the design as you see fit. However, you need to collect feedback from at least one stakeholder. The optimum would be three stakeholder/customer “interviews”.
• You should describe in a sentence or two how you changed your design based on the feedback you received.
• You can use D flip flops, T flip flops or J-K flip flops in your design. The type does not matter. Mixing different types of flip flops with different trigger edge sensitivity is possible but not recommended.
• You need to properly document your designs. If you do a “classic” paper-based design, you need to include diagrams and state tables as well as K-Maps and logic. If you decide to go with a different implementation (ROM, HDL), you need to comment your code.