Devlog 002: IT HAS EYES (and other developments)

What’s New:

• Ultrasonic sensor to control the LCD display
• Detailed schematics drawn

The Eyes

I added an HC-SR04 ultrasonic sensor and programmed the Arduino to only wake the LCD when an object is within about 50 cm.
The idea is that the status screen should only come on when someone is actually AT my door, saving power without changing how the project feels to use.
The fun thing about ultrasonic sensors is that they work by sending out sound waves and waiting for them to return. The sound waves are too high frequency for us to hear…but your phone mic picks them up just fine. The result sounds like a tiny helicopter possessed by demons (check the vid).

The boring stuff (schematics)

You’ll notice I’m logging over 5 hours. Take a guess at how many of them were spent drawing these stupid fancy doodles. Go on. I’ll wait.

It was 4 HOURS. I spent 4 HOURS drawing and redrawing circuits. If these circuits don’t work I think I will die.

Anyway…these schematics aren’t for the prototype you’ve already seen. They’re for the next upgrade.
In Devlog 001 I mentioned wanting to control the display remotely from my desk. Well, it’s finally time to make that happen.

In the schematic, I replaced the Arduino Nano in the LCD circuit with an Arduino UNO, which gave me enough spare GPIO pins to wire on CC1101 radio transceiver. I also moved the pushbuttons onto a separate circuit (also attached). This circuit is the transmitter and will sit on my desk.

Next Steps

• Order more parts (voltage regulators, capacitors, etc)
• Finally build the circuit

Hopefully the next update will feature the first successful radio transmission. If not, it’ll feature a lovely video of me punching a wall.

Wish me luck.

Chao