Instructables

Step 7: How it works

Picture of How it works
This circuit does more than just display some graphics and text on the screen. If it did that , then it wouldn't be self destructing.
The first sketch that should be run, is create mission objective sketch, this sketch uploads a character array to the memory chip, THIS is the mission objective/message that is destructed.
In the second sketch, Self Destructing Msg, a few things happen. At startup there is a idle screen, with the logo that moves across the screen. The button pin is checked for its state. If the button state is high, it goes into the reading function in the program. This function reads, data from the memory chip, then stores it in an array on the arduino memory.
The next function reads the array, and sends it to the display. after a set amount of time, to allow the user to read the message, it waits 5 seconds, then the important part.
All arrays with the message, are overwritten, and no evidence is left behind. If the button is pressed again, a different message is displayed, and the original secret message cannot be recovered.


What's going on in the video:

<8s - Idle screen, logo moves up and down.
*Button Pressed and held*
>8s && <=11s - Splash screen
-read data from memory
-write data to array "cache"

>=11s && <18s - Displays Secret Message

>19s && <24s - 5 second countdown
-Erase array (overwrites)
-Erase FM24C04 (overwrites)

>24s && < 30s - Returned to Idle screen
*Button Pressed*
(There is nothing to read from the memory chip, and nothing in the array cache" All evidence is gone. In addition, the loop that displays the secret message, is also only run once. Every time after that, the program automatically goes into the second loop, which has a complete different set of instructions, which, in the video, displays "nothing to see here!")

-enter 2nd loop
-no valuable data
 
 
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