1. Lesson 3
Sub-Routines

2. Lesson Objectives To understand how to use values to control systems
To understand what sub routines are, and how they are used to make control technology more efficient.

3. It has 4 inputs. 3 buttons and a dial
Task 1: Mobile
This mimic is a child's cot mobile.
It has 4 inputs. 3 buttons and a dial
It has 6 outputs. A motor which turns the mobile, and 5 lights/motors on each vehicle

4. Values
At the top of a mobile is a dial. We can set it to different values from 0 to 100 which increment by 5 each time
How might we use this dial? What could we use it to control?

5. Values
We can speed up the motor depending on the value of the dial above it.

6. Task 1:
Create a flow diagram so that the motor goes forward at 20% when the value is equal to 10

7. Task 2:
Make the motor turn faster as the value increases.

8. Task 3:
Add 3 further flow diagram to program what will happen when the 3 buttons are pressed.
Remember there are several more outputs that you can include.

9. These flow charts are used the control a railway crossing barrier.
Start
Start
Start
Start
Train from track 1?
Train from track 2?
Train from track 3?
Train from track 4?
These flow charts are used the control a railway crossing barrier.
Light on
Light on
Light on
Light on
Light off
Light off
Light off
Light off
Light on
Light on
Light on
Light on
They all makes the lights flash before they close the barrier.
Why is it inefficient to write the same command 4 times?
Light off
Light off
Light off
Light off
Close Barrier 1
Close Barrier 2
Close Barrier 3
Close Barrier 4

10. Extension: Sub Routines
Sub routines are used when the same flow chart is being used several times.

11. Start
Start
Start
SUB FLASH
They work like this
Train from track 1?
Train from track 2?
Train from track 3?
Light on
Light off
SUB FLASH
SUB FLASH
SUB FLASH
Light on
Close Barrier 1
Close Barrier 2
Close Barrier 3
Light off
Each of the flow charts now includes a sub routine. This makes the flow chart more efficient. It saves time for the programmer and the computer.
Stop

12. Sub routines in the mobile
Create a sub routine to program the lights and motors on the vehicles.