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Project Notes

#219 DS18S20 1-Wire Reading

Basic interrogation of a DS18S20 using 1-wire protocol



The DS18S20 is an inexpensive 1-Wire digital thermometer with a range of -55°C to +125°C, at ±0.5°C Accuracy from -10°C to +85°C.

It comes in TO-92 packaging and may be powered directly (using three pins), or take parasitic power from the data line (using two pins).


Basic Operation

The sequence of operations boils down to this:

  • Send a search request on the wire to find a device
  • Get the device address and ensure the family code is as expected
  • Issue conversion command (0x44)
  • Wait for conversion, then read the conversion scratchpad from the device
  • Process the data received

Family Codes

Model Code
DS18S20 0x10
DS18B20 0x28
DS1822 0x22

Example Code

The OneWireReading.ino sketch is a basic demonstration based on the examples on the OneWire Arduino playground page.

I’ve refactored a little to make the code more readable.

It constantly polls the DS18S20 device and logs to the serial output. Here’s an example:




The Schematic


Credits and References

Project Source on GitHub Project Gallery Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.