DingBot debuts

I’ve now got a running prototype of what we’re calling the “DingBot,” a paging system for use between the floors of our house.

Background

This grew out of the Free Rain project, where I was building a wireless network to control irrigation on small farms. The first prototypes I built were the “TempBot,” a remote temperature tracker, and then the “FlowBot,” which could turn a solenoid valve on and off. Both of these had pushbuttons on them as well, for diagnostic and setup. To test out the system, I put the nodes in various places around the house.

We discovered that it was quite handy to have a little pushbutton on the first floor that the life partner could use to page me in my office on the third floor. The FlowBot worked well for this, since for prototyping its solenoid valve was replaced by a small LED; I could confirm her page by turning the LED on and off from my computer.

Now that Free Rain is dead (or at least resting), we decided it would be fun to build out the pager a bit more, and thus was born the DingBot.

Overall design

At present, there are two nodes. One is in my office, powered by AC, and is on all the time. The other, on the first floor, is powered by two AA batteries, is on only when needed, and is otherwise identical. They have two buttons: the Call button and the Respond button. Each plays a distinct musical phrase when pressed, and broadcasts a message so the other node (and all nodes in the house, once I build more) will play the same phrase as well.

The idea is that you press Call to say “come here”; if the other person can and will, he presses Respond. He may also press Respond again when he’s actually coming, if it takes a few minutes. You can also send an unsolicited Respond to just say “I’m here” without issuing a summons.

Right now, the two musical phrases (“shave and a haircut” and “two bits,” respectively) are built into firmware, but they’re stored very similar to MIDI data, so it should be simple later to allow uploading sounds from the PC over wireless from standard MIDI files. This would make it easy to change them frequently, which seems like it would be fun.

Current status

At the moment, since the first-floor node is battery-powered, paging really only works one-way, because that unit’s not likely to be on to hear my page from the third floor. But it will be symmetrical once I get another 3.3V power supply.

Range tests were interesting; the upshot is that without an external antenna, range is terrible, but with one (on either module), there’s no problem reaching any part of the house.

I’ll post pictures, technical data, and more updates as it gets more polished; for now, it doesn’t look significantly different from the FlowBots from the Free Rain project.