Last modified 19 months ago Last modified on 09/06/2015 08:39:13 PM

Simple thermometer

A simple modification of the router with a thermometer is a low cost, easy way how to turn your router into a mini weather station.


The exact operation of the circuit is explained on the website, including a simple DIY procedure.

This circuit is a simple dual simplex to half-duplex driver for 1-wire devices, although it does not work with all of them, because some draw too much current. It was designed and tested for DS18B20+ 1-wire digital thermometer. The parasite power only version - DS18B20P is not supported.

There are four elements plus a thermometer, three 0805 SMD resistors and a general purpose PNP transistor. These elements are generally available everywhere, there are kits sometimes available within wlan-si network.

Example node

You can see how temperature mesurements look on our test Wlan-si node kozolectest.

Linksys version

The following PCB was designed to be used with Linksys routers and enable a simpler construction of such thermometers.

Circuit schematics:


Element placement.

Razporeditev elementov

This is the un-mirrored 1:1 print of the circuit. Available in PDF.


On EXTERNAL port additional thermometers can be attached, but the cable has to be kept reasonably short, lets say about 2m.

If you require a circuit board, you can try asking for it on mailing lists or chat.

TP-LINK version

This circuit board is identical to the previous one, placement of the elements is adapted to the TP-LINK serial port pinout, to enable as painless integration as possible. This documentation is written as a step by step guide.



  1. Obtain all the components
    1. 2x 4.7kOhm resistor (SMD marked with 473)
    2. 47kOhm resistor (SMD marked with 473)
    3. PNP transistor BC556 (or equivalent)
    4. DS18B20+ thermometer in TO-92 case
    5. circuit board
  2. Place the circuit board in front of you, so you can read the markings normally. Solder 4.7kOhm resistors on two vertical places on the left side of the board, marked R1 and R2.
  3. Solder 47kOhm resistor on the horizontal space for resistor marked R3.
  4. Place the transistor T1 on the board, so that its body is on opposite side of the board(where are no copper traces) and solder it into place. The rounded part of transistor body has to point in the direction of
  5. Solder the thermometer on the buard just as you did the transistor into slot marked IC1. The rounded part of thermometer body has to point in the direction of
  6. Connect this board to the routers serial interface.
  7. Make sure you have the correct digitemp module loaded on your router. The temperature graph should appear within a few minutes on

If there are any problems, please seek help.