The Problem:

A frequent problem I have when creating a new Raspberry Pi-based project is determining the IP address of the device.  I am often working with Pi projects in a "headless" (no monitor) configuration using SSH to log in from a PC on the same LAN network.  But to log in this way, I need the Pi's IP address, which sets up a chicken-and-egg problem that goes like this:

I want to connect (SSH) to a headless Raspberry Pi, but before I can do so, I first need to attach a monitor and keyboard to it to login locally and get its IP address (with 'ifconfig'). 

This is the very thing I would like to avoid since the system will ultimately be "headless".  In truth, while it is only a minor inconvenience, it is one I'd like to do without.  The more new RPi systems that you set up, the more tedious it is to pull out a monitor and keyboard to find the IP address of each one before you can begin remotely connecting to it over the LAN using SSH.

My Solution:

I would like to be able to find the IP address of a headless RPi without having to connect a monitor and keyboard to it.  Ideally, I would be able to connect my new RPi to my network, and know the IP address that is it assigned.  Then, I could simply connect directly to it using SSH from my PC on the same network.

As is the case for many others, my minor annoyance at "the problem" turned into a full-blown project to solve it.  I created a program I called Hello Pi that can be run on a Linux or Windows computer to identify the IP address of a Pi (or other device) connected to the same network segment.

We all love the subtle, intermittent glow produced by fireflies in the summertime. Each firefly produces its own unique visual pattern in response to the signals given off by its neighbors. Running through the yard trying to catch them is a quintessential Summer activity for young (and not-so-young) children. Kids will often collect them and put them in a jar to bring in the house to enjoy the light show that the fireflies produce before releasing them to go on their merry, little ways.

This project attempts to replicate the beauty and ambience created by a Mason jar of fireflies. But unlike the "real thing", this virtual jar of fireflies can be enjoyed year-round without having to capture and maintain the little buggers.

Note: This is a cross-post of the project I posted on hackaday.io at: ( https://hackaday.io/project/193890-virtual-jar-of-fireflies ). The majority of the components in the project are from Adafruit, so I thought I'd include it here as well.

The Jar

When I originally designed this project in 2020, I chose to house the virtual fireflies in a plastic Mason jar with a plastic lid. Although it looks more attractive in a glass Mason jar (see pics and vids), I was making it for my son and wanted it to be able to survive being dropped without causing a safety hazard. I built all of the circuitry on a protoboard small enough to fit in the lid of the jar along with the rechargeable LiIon battery. A capacitive touch sensor placed under the center of the lid detects a hand "press" to control turning the jar on and off. A built-in LiIon charger allows the battery to be recharged by connecting a USB charger via a micro-B connector when the lid is off of the jar. Once the jar is powered on, it is configured to operate for 1 hour before automatically powering off (if not manually powered off sooner). This is long enough to allow it to be used as a calming nightlight while children (or adults) are drifting off to sleep.