I started with simple state machines last week. This week I want to talk about more complex state machines and interrupts. These are software topics but we’ll get back to the hardware soon.
The karaoke buttons that control music playback are far more complicated than either its disco button or the quadcopter’s power on sequence; if you press play on the karaoke, what happens? What if the door is open? What if there is no CD? What if it is already playing?
Read MoreHaving considered digital inputs and outputs, you’ve already seen more than 50% of a toy’s hardware. Oh sure, we should talk about the fancier sensors, motor control, and audio outputs but those are one-offs, specific to a toy’s particular function. Many toys don’t have them or only have one; buttons and lights are enough for some toys...
I’ve mentioned the processors in the toys a few times. I can’t show you what is inside the software (partially because the designers sensibly locked out the ability to read the code from their processors). I can show you how to figure out what is in the software without breaking any laws or copy protection.
Last week, I introduced two inputs on karaoke: the power button and the door-closed switch. Those are simple buttons: one electrical line carries one digital signal.
This week, I’ll show how to put a lot of buttons on a few electrical lines and introduce some non-digital signals.
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Confession time: I hate blinking lights. Oh, I know, I read (and wrote!) the last few posts and I like controlling LEDs as much as the next engineer, but I don’t like seeing lights blink. They’re often too bright, too annoying, and too useless. Pushing buttons, on the other hand… well, if the world ends, it might be because I wanted to know what would happen when I pushed some big red button.
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Having looked at the voltage of simple LEDs in the quadcopter and used beep mode to figure out BB-8’s more complicated LEDs, this week I look at how to make many lights turn on and off.
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I'm writing a book about how to learn embedded software concepts by taking apart toys. This is the first chapter. I hope you enjoy it.
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I talk to many engineering friends who say they took apart their toys (and everything else). I was not like that. I didn’t know it was possible to take objects apart. I definitely didn’t know how much I could learn. I never imagined how fun it would be.
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