PICAXE-08M - DS18B20 Interface. Temperature Measurement using the Dallas DS18B20 - PICAXE-08M copyright, Peter H Anderson, Baltimore, MD, Sept, '04 Introduction This discussion offers a number of techniques to implement various temperature measurement systems using the lowcost PICAXE-08M (nominally $3.25) and the Dallas DS18B20 1-W temperature sensor. Note that when used with the PICAXE, the DS18B20 must be powered with +5 VDC. An obvious question is how far the DS18B20 units may be located from the PICAXE. Program DS18B20_08M_1.Bas. This program interfaces with three DS18B20 sensors on separate twisted pair runs. This data is sent to the PC using the SerTxD command, which is 4800 baud for the PICAXE-08M. In this implementation, the ReadTemp12 command is used to read the temperature into word variable TReading. In this implementation, the three measurements are performed and the results sent to the PC or similar, followed by a pause. Program DS18B20_08M_2.Bas The PICAXE is configured for a polled interrupt, high on Pin3.
Playground - OneWire. About: 1-Wire 6 Channel Master Hub | Shelly Park Weather Station. Model: 1-Wire 6 Channel Master HubPurpose: Provides connectivity to 6 separate 1-wire networks to a PC The 1-Wire 6 Channel Master Hub is the heart of the 1-Wire Weather Network. It has 6 Ports which you can plug 1-Wire Networks into. It connects to a PC via a Serial Port (RS-232). With 1-Wire you don’t want to create a “single network” witch looks like a star topology instead you need to daisy chain sensors. In our case trying to daisy chain all the sensors into a single network was unrealistic as I would need to use double the amount of cable. Click here to see a short video of the Hub in operation, controlled by Weather Display (Click for larger image) Hobby-Boards 1-Wire Master Hub.
Simat 1-Wire Projects - Weather Station, Hub, Barometer, Environmental Projects, Satellite Position Controller, Door Access Controller, Gas Meter, Power Meters. At the end of 2000 I started writing my own weather station / HVAC software in VB5 and thought that it would be a good idea to include support for the DS2409 microlan coupler chip, this way I would be able to have a large 1-wire network with branches to each room for DS1820 temperature sensors as well as a WS-1 weather station on the roof. If I didn't include support for the DS2409 then I would be risking my 1-wire network grinding to a halt due to the many reflections caused by the unbalanced cabling system.
A reflection is when the the signal sent down a cable comes back up the cable, this would happen on 10Base2 ethernet if it wasn't terminated with a 50 ohm load at each end of the cable, this has the effect of giving you a balanced impedance transmission line, with the impedance between inner and outer core being virtual equal along the length of the cable. 1-Wire Hub Topology Diagram in PDF format. download The prototype case and circuit board. The final version.