The Clock System

Goals
Instructions
Figures
1. Figure 1
2. Figure 2

In your quest to master digital clockmaking, you discover that an alarm clock has two essential functions: displaying the current time and sounding an alarm at a set time. Being a smart computer engineer, you decide to first tackle the base problem, creating a clock. Quickly, you realize that creating a clock is no easy feat, but luckily your mentor provided you some diagrams for you to better understand the “complex” workings for a clock.

Figure 1 provides a nice outline for the flow of a clock, but you then question what would happen if the clock loses power? Ever the eager apprentice, you are two steps ahead, and propose a plan of allowing the user to manually set the alarm time. Your mentor however is three steps ahead of you, and reveals yet another flowchart (Figure 2) on how to properly implement the time setting logic.

The last question prying at the back of your mind is how to create a “variable” of sorts in hardware? Your mentor, seeing your distant gaze provides you with a final gift before letting you work. He provides you with a BabylonianClock component, a clock that perfectly encapsulates the logic in Figure 1 for you!

Feeling a renewed sense confidence, you thank your mentor and set out to create the setting logic detailed in Figure 2.

Goals

Learn how to use Digital
Create a clock capable of:
- Displaying the current time
- Setting the current time

Instructions

All of your work should be in a new circuit called ConventionalAlarmClock (it will save as ConventionalAlarmClock.dig).

You are given a BabylonianClock component, which implements the logic discussed in Figure 1. Your task is to implement a scaffolding around this component which allows the user to manually set the minutes and hours of the clock.

If you refer to the circuit structure, there are a couple of important inputs to keep in mind:

CLK
CLR
SETUP_TIME
MIN_ADV
HR_ADV

Normal Operation

The normal operation of the clock is defined to be the period where no SETUP signals are high. During this period, the clock will tick away as per Figure 1, keeping track of time like we would expect a clock to.

Please wire up the correct inputs to the BabylonianClock to observe this normal operation.

Setting Time Operation

During the setting time operation, the SETUP_TIME signal will be high. While this signal is set high, the external clock input (CLK) should not modify the stored time in BabylonianClock in any way. During this operation, the advance signals (MIN_ADV or HR_ADV) can be set high. On rising edges of these signals (i.e. the signal goes from 0 to 1), then the corresponding counter storing the value should be incremented by 1.

Hint

A CLK signal to the BabylonianClock will increment the SECONDS by 1 only on rising edges. Perhaps this port could be reused?

Example

Suppose the clock is at 00:00:54 and in setup mode. Suppose that we get the following input waveform:

CLK    : ⎽⎽/⎺⎺\⎽⎽/⎺⎺\⎽⎽/⎺⎺\⎽⎽/
MIN_ADV: ⎽⎽/⎺⎺\⎽⎽/⎺⎺\⎽⎽/⎺⎺⎺⎺⎺⎺
HR_ADV : ⎽⎽⎽⎽⎽/⎺⎺\⎽⎽/⎺⎺⎺⎺⎺⎺⎺⎺⎺

Then the final time the clock should display is 02:03:54 as:

Being in setup mode means that the clock doesn’t advance the seconds anymore
MIN_ADV had 3 rising edges, hence we have incremented by 3 minutes
HR_ADV had 2 rising edges, hence we have incremented by 2 hours

Please wire up the correct inputs to the BabylonianClock to observe this setting time operation.

Displaying the Time

To display the time, we will be utilizing Seven Segment Displays. The TickTok Display Team has provided you with a SevenSegmentDecoder component.

Please wire up the correct inputs to the SevenSegmentDecoder and export the correct outputs.

Figures

Figure 1

Clock Logic Flowchart

flowchart TD
    A[Wait 1s]
    B["seconds = seconds + 1
    display(seconds)"]
    C{seconds &ge; 59?}
    C1["seconds = 0
    display(seconds)"]
    D["minutes = minutes + 1
    display(minutes)"]
    E{minutes &ge; 59?}
    E1["minutes = 0
    display(minutes)"]
    F["hours = hours + 1
    display(hours)"]
    G{hours &ge; 23?}
    G1["hours = 0
    display(hours)"]

    A --> B
    B --> C
    C -->|No| A
    C -->|Yes| C1
    C1 --> D
    D --> E
    E -->|No| A
    E -->|Yes| E1
    E1 --> F
    F --> G
    G -->|No| A
    G -->|Yes| G1
    G1 --> A

Figure 2

Setting Time Flowchart

The symbol ⎽⎽/⎺⎺ denotes a rising edge, or when the signal goes from a 0 to a 1. Similarly, the symbol ⎺⎺\__ denotes a falling edge, or when the signal goes from a 1 to a 0.

flowchart LR
    A{SETUP_TIME == 1?}
    B{MIN_ADV ⎽⎽/⎺⎺ ?}
    C["minutes = minutes + 1
       display(minutes)"]
    D{HR_ADV ⎽⎽/⎺⎺ ?}
    E["hours = hours + 1
       display(hours)"]

    A ---->|Yes| B & D
    B ---->|Yes| C
    D ---->|Yes| E

    A & B & D -->|No| A

    C & E --> A