Useful links for further reading on 1-Wire sensing and home automation

The resources that 1-Wire hobbyists relied on in the early 2000s were scattered: personal project pages, link directories, message boards and magazine sites. Many of them no longer exist, and a list full of dead links wastes a reader's time. So the rule here is simple: a link appears only if it points to a maintained source that still answers today, published by the manufacturer, an established open-source project or the vendor of the software concerned.

That rule leaves out several names familiar from the kits' era, including a UK home automation link directory, the Hometoys home automation magazine and the personal project pages of individual 1-Wire builders. They were valuable in their time, but their content is no longer reliably reachable. The topics they covered, such as weather stations, humidity sensing and cabling, are handled on this site in the 1-Wire weather station guide and the overview of 1-Wire today.

The 1-Wire bus was developed by Dallas Semiconductor. Maxim Integrated took over the product line, and Maxim is now part of Analog Devices, so the official datasheets and application notes live on analog.com. Each device has its own product page with the current datasheet, evaluation tools, related application notes and the part's production status.

• DS18B20 programmable-resolution digital thermometer: the most common 1-Wire temperature sensor, and the one most current software expects.
• DS2438 smart battery monitor: the chip inside most 1-Wire humidity sensors and barometers, including the Midon MD3020E.
• DS2408 8-channel addressable switch: the I/O chip used on the 1WIO relay and LED module.

When a datasheet from an old kit manual disagrees with the manufacturer's current version, trust the current one.

OWFS

OWFS, the 1-Wire File System, presents every device on a 1-Wire bus as a directory of files. A temperature sensor becomes a folder with a file called temperature, and reading that file returns the current value. OWFS works with USB and serial bus masters, and it includes a server that other programs can query over the network. The project is made of several small programs: owserver talks to the bus master and answers requests over the network, usually on port 4304; owfs mounts the bus as a file system; and owhttpd shows the same tree in a web browser. It is the usual choice for anyone who wants to read 1-Wire sensors from scripts or from a Linux machine without writing bus timing code.

The Linux kernel w1 subsystem

Linux has its own 1-Wire support in the kernel, called w1. The kernel's w1 documentation describes the bus master drivers, the slave drivers for families such as the DS18B20 thermometer, and the sysfs interface through which readings appear. On small single-board computers, a DS18B20 wired to a GPIO pin with a pull-up resistor can be read through w1 with no extra hardware, which makes it the modern equivalent of the serial boxes the kits provided.

A TEMP08 or LOG08-II still in service talks plain ASCII over RS232, so it does not need OWFS or the kernel driver at all; any serial terminal or script can read it. The sensors on its bus are ordinary 1-Wire devices, though. If the interface itself fails, the same thermometers, counters and humidity boards can usually be moved to a USB bus master and read through OWFS, the w1 driver or Home Assistant. Check each device family against the software's supported list before rewiring, and keep the cabling advice in the 1-Wire network wiring guide in mind when the network is long.

One practical detail: the old interfaces reported sensors by their 64-bit ROM codes, and so do OWFS, the w1 driver and Home Assistant. Writing down the ROM code, location and purpose of each sensor before a move saves a great deal of guesswork afterwards, because the new software will list the same devices by the same codes.