which digital thermometer to use?
OakGraphics
Posts: 202
I have been looking at the DS series digital thermometers, and I am trying to find an easy - multi thermo solution with the least amount of pins.
I see the DS1820 is a 1-wire, and it looks the simplest to set up. I essentially need 6 or so temps monitored for motor and power supply thermal shutdown circuits.
I am using a propeller for this, and plan on showing the temps on an lcd / tv screen or maybe 7-segment led readouts.
Any suggestions?
Each thermo will be about 3 to 6 feet away from the 'base', and first thought was in a star topography, but have read in the ds1820 that it might not be the best way. I could string them in parallel, and in bridge mode (drop downs of 3 feet from parallel run). I need to monitor temperatures in upwards of 125c for stepper motors.
Thanks in advance,
Daniel
I see the DS1820 is a 1-wire, and it looks the simplest to set up. I essentially need 6 or so temps monitored for motor and power supply thermal shutdown circuits.
I am using a propeller for this, and plan on showing the temps on an lcd / tv screen or maybe 7-segment led readouts.
Any suggestions?
Each thermo will be about 3 to 6 feet away from the 'base', and first thought was in a star topography, but have read in the ds1820 that it might not be the best way. I could string them in parallel, and in bridge mode (drop downs of 3 feet from parallel run). I need to monitor temperatures in upwards of 125c for stepper motors.
Thanks in advance,
Daniel
Comments
I haven't checked lately to see if it was updated but the 1-wire object, SpinOneWire, needed a slight mod to do negative temps.
My .02 cents worth.
Thats sounds good. I would pretty much have the same rig so I will go that route. I don't expect to be in negative temps while operating it, but would still like to know the mod if you had it lying around, or I will search the forums to see what the fix was.
Sounds fun!
temperature := ~~temperature {Modified 9 Dec 2008 to provide negative temps.}PRI ReadTemperature(ThermalAddress) | temperature, degC, degF, WatchDogDS18b20 {Read the temperature from a DS18B20 sensor.} {Waits up to 10 seconds for the sensor to provide data.} ow.reset ow.writeByte(ow#MATCH_ROM) ow.writeAddress(ThermalAddress) ow.writeByte(ow#CONVERT_T) {Reset WatchDogDS18b20 to zero...} WatchDogDS18b20 := 0 repeat {Repeat until the called sensor tells us it is ready to give data...} waitcnt(clkfreq/100 + cnt) {Increment the watch dog on every pass and if the wait for a sensor exceeds about 1000 iterations, then there is a problem, therefore return to main program.} WatchDogDS18b20 := (WatchDogDS18b20 + 1) IF WatchDogDS18b20 > 1000 {About 10 seconds.} {Consider lighting up a warning LED.} return IF ow.readBits(1) 'The sensor is ready to provide data. ow.reset 'Say okay and prep the data line. ow.writeByte(ow#MATCH_ROM) 'Tell the sensor you want to match a ROM ow.writeAddress(ThermalAddress) 'Send out the ROM to match. ow.writeByte(ow#READ_SCRATCHPAD) 'Open up the sensor's scratchpad. temperature := ow.readBits(16) 'Read the data. temperature := ~~temperature {Modified 9 Dec 2008 to provide negative temps.} ' Convert from fixed point to floating point degC := f.FDiv(f.FFloat(temperature), 16.0) ' Convert Celsius to Fahrenheit degF := f.FAdd(f.FMul(degC, 1.8), 32.0) result := degF {The result is the temperature in degrees F.} return 'Return to the main program... {*** End of method ReadTemperature ***}cool beans - literally!