Timing with no processor: the 555
A resistor, a capacitor and a 555 make a square wave with no code in sight. Measure it, then change the parts to change the rate.
Open it in the simulatorAll paths
The twelve week course
The classroom course, week by week: a loop on a breadboard through to a board talking over serial.
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What you will build
3 projects, built step by step
12 lessons in 3 chapters, about 24 hours on a simulated breadboard. Free, in your browser, every step checked by the simulator.
More outputs than pins: the shift register
Three pins in, eight out: a 74HC595 shifting a byte and latching it.
Open it in the simulatorProject week: two boards, one wire
Plan a system, agree a protocol, share a ground, and present it as a link.
Open it in the simulatorThe map
Chapter by chapter
Each lesson opens when the one before it is done, and each chapter ends in a project.
Chapter 1
Weeks 1 to 4
A loop, a board, a button and a timer.
- Open160 XP
A first circuit
One loop on a breadboard: five volts, a pushbutton, a resistor and an LED. Build the habit of reading a circuit as a loop, and work out the current in it.
0 of 6 steps
- Locked135 XP
Blink: the first program
An Arduino Uno, one pin and a program. Drive an output from code, watch the timing be real, and find out what delay() costs you.
0 of 5 steps
- Locked160 XP
Reading a button, and printing what it says
A pull-up, a pin that reads low when the button is pressed, and a count printed to the serial monitor. Finish by catching the contacts bouncing.
0 of 6 steps
- ProjectLocked320 XP
Timing with no processor: the 555
A resistor, a capacitor and a 555 make a square wave with no code in sight. Measure it, then change the parts to change the rate.
0 of 6 steps
Chapter 2
Weeks 5 to 8
Logic, memory and the parts that hold a value.
- Locked10 XP
Logic gates, as real chips
AND, OR, XOR and NOT on 74HC chips with supply pins and propagation delay.
- Locked10 XP
Arithmetic from gates: the full adder
Two XORs, two ANDs and an OR add one bit and carry into the next.
- Locked10 XP
Memory: flip-flops and counters
A D flip-flop wired to toggle divides a clock by two; four of them count.
- ProjectLocked20 XP
More outputs than pins: the shift register
Three pins in, eight out: a 74HC595 shifting a byte and latching it.
Chapter 3
Weeks 9 to 12
Shifting, shaping and talking to something else.
- Locked10 XP
Pulse width modulation and the eye
One pin switching fast enough that a fraction of the time looks like a fraction of the brightness.
- Locked10 XP
Serial: making the board talk
Printing to the monitor, reading what is typed back, and the time a baud rate costs.
- Locked10 XP
Interrupts: events instead of polling
A handler that runs the moment a pin changes, and the rules that come with it.
- ProjectLocked20 XP
Project week: two boards, one wire
Plan a system, agree a protocol, share a ground, and present it as a link.
Syllabus
Every lesson in the course
All 4 lessons, in order, each with what it covers. Any of them opens in the editor right away.
Weeks 1 to 4
- A first circuitOne loop on a breadboard: five volts, a pushbutton, a resistor and an LED. Build the habit of reading a circuit as a loop, and work out the current in it.
- Blink: the first programAn Arduino Uno, one pin and a program. Drive an output from code, watch the timing be real, and find out what delay() costs you.
- Reading a button, and printing what it saysA pull-up, a pin that reads low when the button is pressed, and a count printed to the serial monitor. Finish by catching the contacts bouncing.
- Timing with no processor: the 555A resistor, a capacitor and a 555 make a square wave with no code in sight. Measure it, then change the parts to change the rate.
Weeks 5 to 8
- Logic gates, as real chipsAND, OR, XOR and NOT on 74HC chips with supply pins and propagation delay.
- Arithmetic from gates: the full adderTwo XORs, two ANDs and an OR add one bit and carry into the next.
- Memory: flip-flops and countersA D flip-flop wired to toggle divides a clock by two; four of them count.
- More outputs than pins: the shift registerThree pins in, eight out: a 74HC595 shifting a byte and latching it.
Weeks 9 to 12
- Pulse width modulation and the eyeOne pin switching fast enough that a fraction of the time looks like a fraction of the brightness.
- Serial: making the board talkPrinting to the monitor, reading what is typed back, and the time a baud rate costs.
- Interrupts: events instead of pollingA handler that runs the moment a pin changes, and the rules that come with it.
- Project week: two boards, one wirePlan a system, agree a protocol, share a ground, and present it as a link.
Kits
Build it on your bench too
Every lesson runs in the simulator with nothing to buy. When you want the real thing, these kits have the parts.
Find your kit
Pick the starter kit you own and run every lesson in its manual with the same parts on the same pins.
See every kitQuestions
About The twelve week course
Is The twelve week course free?
Yes. All 12 lessons of The twelve week course are free and run in your browser, with nothing to install and no parts to buy before you start.
Do I need any parts?
No. Every circuit is built on a simulated breadboard, and the simulator checks each step as you go. When you want to build it for real, the same parts and wiring work on a real bench.
How long does The twelve week course take?
About 24 hours: 12 lessons in 3 chapters, each one a few short steps. Your progress is kept, so you can stop after any lesson and pick up where you left off.
What will I build?
Each chapter ends in a project that puts it together: Timing with no processor: the 555, More outputs than pins: the shift register and Project week: two boards, one wire.
Where do I start?
With "A first circuit", and each lesson builds on the one before it. New to circuits? Electronics basics is the course that starts from zero.