# Seven Segment Display
Purpose Of This Page
This page explains how to show numbers on the CodyNick Seven Segment Display using Python.
The Seven Segment Display is useful for showing:
- Scores.
- Counts.
- Sensor values.
- Timer values.
- Simple numeric feedback.
By the end of this page, students will be able to:
- Display a positive number.
- Display a negative number.
- Display a decimal number.
- Update the displayed value inside a Python program.
Figure 1 - CodyNick Seven Segment Display for showing numeric values.
Start Code
Every CodyNick Python script should import the CodyNick library and connect to the CodyNick device.
```python
import CodyNick
cn = CodyNick.CN()
```
The variable `cn` represents the connected CodyNick device.
Display A Number
Use `Seven_Segment.display()` to show a number.
Function format:
```python
CodyNick.Seven_Segment.display(cn, value)
```
Example:
```python
import CodyNick
cn = CodyNick.CN()
CodyNick.Seven_Segment.display(cn, 1234)
```
This displays `1234`.
Display A Negative Number
The display can show negative values.
Example:
```python
import CodyNick
cn = CodyNick.CN()
CodyNick.Seven_Segment.display(cn, -123)
```
This displays `-123`.
Display A Decimal Number
The display can also show decimal values.
Example:
```python
import CodyNick
cn = CodyNick.CN()
CodyNick.Seven_Segment.display(cn, 1.234)
```
This displays `1.234` if the value fits on the display.
Using Strings Or Numbers
The value can be passed as a number:
```python
CodyNick.Seven_Segment.display(cn, 1234)
```
It can also be passed as a string:
```python
CodyNick.Seven_Segment.display(cn, "1234")
```
Both examples display the same value.
Display Range
The display is designed for short numeric values.
Typical useful values are:
| Type | Example |
|---|---|
| Positive integer | `1234` |
| Negative integer | `-123` |
| Decimal number | `1.234` |
| Small decimal | `-1.23` |
Very large or very small values may not fit on the display.
In the CodyNick Python library, values outside the normal display range are treated as out of range.
Example: Count Up
This example counts from `0` to `9`.
```python
import CodyNick
import time
cn = CodyNick.CN()
for number in range(10):
CodyNick.Seven_Segment.display(cn, number)
time.sleep(0.5)
```
The number changes every half second.
Example: Countdown
This example counts down from `5` to `0`.
```python
import CodyNick
import time
cn = CodyNick.CN()
for number in range(5, -1, -1):
CodyNick.Seven_Segment.display(cn, number)
time.sleep(1)
```
The third value in `range(5, -1, -1)` means the loop counts down by `1`.
Example: Show Decimal Values
This example displays a few decimal values.
```python
import CodyNick
import time
cn = CodyNick.CN()
values = [1.234, 2.5, 3.75, -1.23]
for value in values:
CodyNick.Seven_Segment.display(cn, value)
time.sleep(1)
```
Function Summary
| Function | Purpose | Example |
|---|---|---|
| `Seven_Segment.display(cn, value)` | Display a number | `display(cn, 1234)` |
Practice Tasks
Try these exercises:
1. Display `1234`.
2. Display `-123`.
3. Display `1.234`.
4. Count from `0` to `9`.
5. Count down from `9` to `0`.
6. Display a list of decimal values.
7. Create a timer that counts seconds.
Common Mistakes
The first argument must be the connected CodyNick device:
```python
CodyNick.Seven_Segment.display(cn, 1234)
```
This is not correct:
```python
CodyNick.Seven_Segment.display(1234)
```
If a value is too long, it may not appear as expected on the display.
Use short numeric values:
```python
CodyNick.Seven_Segment.display(cn, 1234)
```
When using a loop, add a delay so each value can be seen:
```python
time.sleep(0.5)
```
Page summary:
The Seven Segment Display shows short numeric values. Use `Seven_Segment.display(cn, value)` to display integers, negative numbers, or decimal numbers from Python.