Following on from my adventures with the PS2 keyboard, I modified the code to play tones.
What I like about this is the opportunity to work with arrays. The “FOR” section is key. It scans an array to see if there is a match with the pressed key. If there’s a match, it then uses the position of the array to get the frequency and play it.
A noisy lesson – take a couple of speakers and get them to play a frequency. The frequency range is about 30 hertz to 20,000 hertz. As you get older, the top level you can hear goes down. I like this lesson as it teaches some key words such as frequency, tone, pitch and vibration. It also builds up into teaching the idea of variables as well as functions. Plus it teaches music.
The basic code for Arduino:
tone (10,500); // 10 is the speaker pin, 500 is the frequency.
Easy to pick up. Here’s an example.
It’s just tones at the moment. We can use this to make music as well.
The basic principle of a light alarm is to measure any changes in the light levels. If the level goes above or below a certain level, something is triggered.
I like this because it teaches variables and responding to a change in that variable.
FOREVER measure the light level
IF the level changes, do something.
You can even use the > and < signs to extend it. The circuit is very simple – a light dependant resistor, 10k resistor , 3 wires and an Arduino. You can add more OUTPUTS or use Scratch on screen to do something.
This is an example of Scratch reacting – by 10 and 11 year olds.
RGB LEDs are great. They can produce a range of colours depending on the amount of power give to each LED bulb. Once you have access to the colour codes, you can produce 256 x 256 x 256 colours. Which is a lot of combinations.
We use Scratch For Arduino. This allows you to easily edit the analog power outputs. Put in a delay and a repeat and you’ve got a disco. As it’s Scratch based, it’s easy to do for primary children.
They’re hard to find nowadays. Except if you go to a skip. Or a school. I had an old keyboard lying around so followed a tutorial to get it to work with an Arduino. It’s got 4 cables – Power, Ground, Data and IRQ. You can get adapters or just take the cables apart.
So I thought I’d write some real blog posts, Just a chat about programming and what I’ve found out.
I love music. Well, I say that – I can play the piano with my right hand as long as it’s not too complicated. But I like listening to it and coding it. So some research has opened up the whole new world of maths, music and frequencies. I love teaching it as I can cover maths and science – and get the key words in.
speed of sound = wavelength * frequency
The frequency of A4 (the A after Middle C) is 440 Hz
The wavelength of A4 is 78.41 cm
78.41 * 440 = 34,000 cm / s (Speed of sound = 345 m/s)
As the notes go up, the ratio between the first note and the other notes is related to the (12th root of 2 ) raised to the power of the note number.