Pickaxe Traffic Light Project

From Soldering to Coding

Build & Program the AXE092

Welcome to the AXE092 project page for Year 9 Electronics. This page provides all the background information, examples, and guides you’ll need as you assemble, solder, and program your AXE092 Picaxe experimenter’s board. Your main challenge is to create a traffic light system for a railway crossing.

Parts Required for the Project

About Traffic Lights

Traffic lights are everywhere in our city. They use a combination of red, amber, and green lights to safely manage traffic flow. Modern systems now use LED bulbs, which save huge amounts of power compared to older incandescent bulbs.

Did you know?

Old-style traffic light bulbs used ~100W each.
A busy intersection could have dozens of bulbs lit at once.
LED replacements often use under 20W, saving both money and energy.
Christchurch has converted most intersections to LED lights.

Traffic Light Challenge: Mission Ōtautahi

Investigate how Christchurch traffic lights use and save energy! Research a real intersection, compare old bulbs with LEDs, calculate power savings, and explore the impact of technology on people and sustainability.

Traffic Light Challenge: Mission Ōtautahi Document

What is a PICAXE?

A PICAXE is a type of programmable microcontroller. You can write simple programs in PICAXE BASIC to:

Turn outputs on and off (LEDs, buzzers, motors)
Read inputs (switches, sensors like LDRs)
Control systems (like traffic lights!)

The AXE092 board is a training kit that lets you solder your own circuit and then bring it to life with programming.

AXE092 Assembly Guide

Follow these steps carefully as you assemble your PICAXE AXE092 School Experimenter’s Board. Tick each step as you go, and make sure to include photos and reflections in your documentation.

Understanding the Circuit Diagram

The circuit diagram is like the map or plan for your project. It shows where every part goes and how the parts are joined together with wires. You don’t need to understand every symbol yet — just know that the diagram tells you how the circuit should be connected.

It’s much easier to use a circuit diagram than a photo because it’s clear, simple, and shows all the connections in one place. Later, when you learn to “read” the symbols, you’ll be able to build and fix circuits more easily.

Step 1: Preparation

Lay out all components neatly before you begin.
Take a photo of all the parts before starting.
Keep all small parts safe — you only get one set! Tip: Store loose parts in your project box or small containers.
Review your soldering safety and setup notes.
Take at least five progress photos as you solder your components.

Step 2: Soldering

Remember proper technique:
- Heat the joint, not the solder.
- Use clean, tinned tips.
- Inspect each joint before moving on.
Try to show your technique, clean joints, and board layout with your photos.
When assembling a circuit board like the AXE092, always solder from the lowest (flattest) components to the tallest (highest).

Step 3: Quality Check

When all soldering is complete, visually inspect every joint again.
- Look for shiny, cone-shaped joints.
- Check for bridges or cold joints.
- Have your teacher check connections.
Next: Test the board's interfaces as explained below.

AXE092 Testing Guide

When you start working with your new AXE092 microcontroller board, your first job is to make sure all the ports work properly.

If something doesn’t behave as expected later, come back to these simple mini-tasks to check whether your board or program is at fault.

Most of these can also be tested in Simulation Mode in the PICAXE Editor.

Step 1: Digital Output

For this task, we need to make sure that outputs C.0, C.1, and C.2 work correctly.
Each pin controls an LED — identify which colour is connected to each one on your board.

Example:

C.0 = Green / Red / Yellow LED (choose one and delete the others)
C.1 = Green / Red / Yellow LED
C.2 = Green / Red / Yellow LED

Questions:

What does the high command do?
What does the low command do?
What does the wait command do?
Why does this code never stop running?
Why is this called a digital output?

Example Code

Use the commands high, low, wait, and pause to turn each LED on and off

Step 2: Analogue Input

This test checks that the analogue input is working.

Your board uses an LDR circuit as a voltage divider — just like in the Lighthouse project. The voltage at the input changes with the amount of light on the LDR.

Questions:

What is the value range? (Hint: 0–255 for readadc, 0–1023 for readadc10.)
What is the highest value you see?
What is the lowest value you see?
How does this value relate to the input voltage?

Use the debug window to view the changing value as you shine or block light.

Step 3: Digital Input

This test checks the switch input circuit.

Like the LDR, it’s part of a voltage divider — but a switch can only give two values.

Questions:

What two values can a digital input have?
What is the purpose of this code?
How could you use this in a real project?

Step 4: Sound Output

Now let’s check that your piezo buzzer is working.
A piezo makes sound because a special crystal inside bends when voltage changes rapidly — creating vibrations you can hear.

Questions:

What is a piezo and how does it work?
How could you use sound in your traffic light project?

Step 5: Traffic Light Assessment

Task: Program a "Traffic System."

Red LED turns ON (Stop traffic).
(Wait 5 seconds).
Green LED turns ON (Go).

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