136 lines
3.1 KiB
Markdown
136 lines
3.1 KiB
Markdown
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# Fireflies
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### ~ avatar
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Turn your @boardname@ into fireflies.
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### ~
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https://youtu.be/ZGvtnE1Wy6U
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## How do Fireflies synchronise?
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Go to http://ncase.me/fireflies/ and read about the fireflies synchronization phenomenon.
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## Code
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We want to create virtual fireflies using multiple @boardname@ (each @boardname@ acts as a firefly).
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Let's review some of the key points of the article:
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### "Each firefly has its own individual internal clock"
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A clock in this case is like a counter, so we will start by adding a ``clock`` variable to our program.
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```block
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// the clock ticker
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let clock = 1
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```
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### "and every time the clock “strikes twelve”, it flashes."
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We can use a [forever](/reference/basic/forever) loop to repeat code that increments the clock.
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When the clock reaches "noon" (let's pick `8`), we turn on the screen briefly (by using the game score animation)
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```block
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// the clock ticker
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let clock = 0
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basic.forever(() => {
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// if clock "hits noon", flash the screen
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if (clock >= 8) {
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// flash
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game.addScore(1)
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// wait for 2 ticks
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basic.pause(200)
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// reset the clock
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clock = 0
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} else {
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// just wait a bit
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basic.pause(100)
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// increment the clock
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clock += 1
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}
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})
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```
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### Step 1: when you see a nearby firefly flash, nudge your clock a little bit forward.
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The @boardname@ can send radio messages to neighbor @boardname@.
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We can use these messages to simulate the "flashes" of light.
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* When a firefly flashes, it also sends a number over radio using [radio send number](/reference/radio/send-number).
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```block
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// the clock ticker
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let clock = 0
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basic.forever(() => {
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// if clock "hits noon", flash the screen
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if (clock >= 8) {
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// notify neighbors
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radio.sendNumber(0)
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// flash
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game.addScore(1)
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// wait for 2 ticks
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basic.pause(200)
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// reset the clock
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clock = 0
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} else {
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// just wait a bit
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basic.pause(100)
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// increment the clock
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clock += 1
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}
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})
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```
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* When a firefly receives a radio packet, it increments its clock by one.
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```block
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// the clock ticker
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let clock = 0
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radio.onDataPacketReceived(() => {
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// advance clock to catch up neighbors
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clock += 1
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})
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```
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### Putting all together
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https://youtu.be/XzZeB4yYnEw
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Download this program on as many @boardname@ as you can find and try it out in a dark room!
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(We've added a [radio set group](/reference/radio/set-group) block to specify which group the firefly will communicate on).
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```blocks
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// the clock ticker
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let clock = 0
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radio.onDataPacketReceived(() => {
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// advance clock to catch up neighbors
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clock += 1
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})
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basic.forever(() => {
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// if clock hits noon, flash the screen
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if (clock >= 8) {
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// notify neighbors
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radio.sendNumber(0)
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// flash
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game.addScore(1)
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// wait for 2 ticks
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basic.pause(200)
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// reset the clock
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clock = 0
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} else {
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// just wait a bit
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basic.pause(100)
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// increment the clock
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clock += 1
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}
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})
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radio.setTransmitPower(1)
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radio.setGroup(12)
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```
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```package
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radio
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``` |