{"id":356,"date":"2020-10-28T15:50:38","date_gmt":"2020-10-28T20:50:38","guid":{"rendered":"https:\/\/jimandnoreen.com\/?p=356"},"modified":"2020-10-30T08:29:06","modified_gmt":"2020-10-30T13:29:06","slug":"long-distance-mailbox-alert-using-lora","status":"publish","type":"post","link":"https:\/\/jimandnoreen.com\/?p=356","title":{"rendered":"Long Distance Mailbox Alert using LoRa"},"content":{"rendered":"\n

You’ve got mail! An IoT project using solar power and long range radio<\/h4>\n\n\n\n

In these pandemic times of limited mobility, I become more like a dog every day: looking forward with great enthusiasm to meals, walks and car rides. One of the daily events that’s taken on new importance is walking down to the mailbox. But it’s over 100 yards away from the house, so it’s nice to know when there’s actually something in it to collect. So I devised a means of getting an alert when the mail is delivered.<\/p>\n\n\n\n

There are simple mechanical devices that set a visible flag when a mailbox is opened but ours is too far from the house to see. And the distance exceeds the range of commercially available Bluetooth and WiFi solutions. There is no source of power near the mailbox. Running hundreds of feet of cable seemed like an expensive and impractical means of solving the problem. <\/p>\n\n\n\n

I cobbled together the perfect solution using a repurposed solar-powered floodlight and LoRa transmitter\/receiver pair. LoRa (Long Distance Radio) works great for sending short data packets great distances. Unobstructed range can exceed several miles. LoRa modules are inexpensive and consume very little power.<\/p>\n\n\n\n

An ideal IoT solar-powered enclosure
<\/h4>\n\n\n\n<\/a>\"\"\n\n\n\n

I found a $30 solar floodlight on Amazon that is perfect for this and would be for many other IoT (Internet of Things) projects. The device has a weatherproof enclosure, two user-replaceable 2200 mAh batteries and charging circuit. One screw opens it up and there’s plenty of room inside to add your own circuitry inside. The only deficiency I see with this product is that it lacks an O-ring or other means of weatherproofing, although the Amazon product page claims it is IP65 splash resistant.<\/p>\n\n\n\n

\"\"
Interior of solar panel before any modification<\/figcaption><\/figure>\n\n\n\n

The project is described below in detail below in case you want to build something similar<\/p>\n\n\n\n

Project Summary<\/h4>\n\n\n\n

A pair of LoRa radios is used for this project, one as transmitter and the other as receiver. The transmitter spends most of its time in low power mode with the radio sleeping. In that state it draws only around 10 mA. We’re powering it from the solar panel’s two 2600 mAh batteries, enough to power the module for 500+ hours. That’s a lot of cloudy days!<\/p>\n\n\n\n

Whenever the state of the connected switch changes, the transmitter sends a short string of text: “1” indicating open or “0” for closed, followed by a space then the battery voltage. For example, “1 4.07”. The receiver listens for these packets. When one is received, an LED and\/or servo are activated. <\/p>\n\n\n\n

The LoRa module also echos the message to its serial port for interfacing with other systems (more about that in the next post).<\/p>\n\n\n\n

Keep in mind that this project could be adapted for many other open\/closed, true\/false monitoring scenarios, e.g., driveway gates, doors, motion alarms, etc.<\/p>\n\n\n\n

Bill of Materials<\/h4>\n\n\n\n