1-Wire Energy Management Projects

Home Telemetry and Control Systems to Monitor and Reduce Energy Costs


Here we will explain how monitoring around your home or business is accomplished and what you need to know to make your projects successful. We'll try and cover a different topic each month. Some of the areas we'll cover are:

  • Monitoring temperatures around the house
  • Monitoring the HVAC system (on/off state)
  • Controlling attic fans in the summer
  • Controlling the sprinkler system
  • Monitoring appliances
  • Turning electricity off in sections of the house at night

Let's start by investigating a very popular topic:

 Monitoring Temperatures

Updated: 8/2/2015

Monitoring temperature using 1-Wire is one of the easier projects. There are just a few things you need to know to be successful:

First, the sensors must be connected daisy-chain style or the reliability of the network will suffer. It's exactly as many of the diagrams show. The reason for this is due to the signal going across the data line. The signal must be sent and return from each sensor without colliding with other sensor signals, To accomplish this, only the daisy-chain style network is used.

This unfortunately causes a new problem since it's very difficult to install such a network in your home or business. We have solved that at 1WireBoards. Using our junction board we maintain the "Daisy-Chain" requirement but allow sensors to run down walls and branch out while maintaining the "one-long-wire" reliability.

Diagram A below shows a "perfect" 1Wire network.

Diagram B below is a modified network which allows sensor placement flexibility but still maintains the daisy-chain requirement for reliability. Notice the break in the dataline.

Diagram C is the schematic of the junction board we build.

Second, you need a master-controller. This can be a USBMicro U421 device or can be the DS9490 USB controller  from Maxim-IC and sold by many outlets. I use the Maxim-IC USB controller for temperature since most of the software is already written.

Third, you need software for polling the temperature sensors. All the software we have written is in Visual Basic and is run from a .NET Windows Service.

Fourth, (optional) you need a database to store the information that's recorded. For this we use Microsoft SQL Express which is a free download.

Questions about this project? Contact me at: onewireprojects@outlook.com

Good Luck!


Did You Know?

Each 1-Wire device has it's own 64-bit identification number embedded in the device during manufacturing and it can't be changed.

The number is not repeatable and is used to query a specific device on a 1-Wire network. It's represented as a hexadecimal string.

Typical device identification looks like this:


There's 8 bits to a byte so a 64 bit code translates into 16 hex code string. The two characters on the right (10) represents the device type. 10 is the DS18S20 temperature sensor.