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aucun résumé de modification
{{tmbox | text = En cours de traduction}}
{{tmbox | text = En cours de traduction}}
== Introduction ==
== Présentation ==
=== Introduction ===
An analog temperature sensor is pretty easy to explain, its a chip that tells you what the ambient temperature is!
An analog temperature sensor is pretty easy to explain, its a chip that tells you what the ambient temperature is!
Because these sensors have no moving parts, they are precise, never wear out, don't need calibration, work under many environmental conditions, and are consistant between sensors and readings. Moreover they are very inexpensive and quite easy to use.
Because these sensors have no moving parts, they are precise, never wear out, don't need calibration, work under many environmental conditions, and are consistant between sensors and readings. Moreover they are very inexpensive and quite easy to use.
== Quelques informations ==
=== Quelques informations ===
These stats are for the temperature sensor in the Adafruit shop, the [http://www.ladyada.net/media/sensors/TMP35_36_37.pdf Analog Devices TMP36] (-40 to 150C). Its very similar to the LM35/TMP35 (celsius output) and LM34/TMP34 (farenheit output). The reason we went with the '36 instead of the '35 or '34 is that this sensor has a very wide range and doensn't require a negative voltage to read sub-zero temperatures. Otherwise, the functionality is basically the same.
These stats are for the temperature sensor in the Adafruit shop, the [http://www.ladyada.net/media/sensors/TMP35_36_37.pdf Analog Devices TMP36] (-40 to 150C). Its very similar to the LM35/TMP35 (celsius output) and LM34/TMP34 (farenheit output). The reason we went with the '36 instead of the '35 or '34 is that this sensor has a very wide range and doensn't require a negative voltage to read sub-zero temperatures. Otherwise, the functionality is basically the same.
* [http://www.analog.com/en/mems-sensors/digital-temperature-sensors/tmp36/products/product.html Fiche technique]
* [http://www.analog.com/en/mems-sensors/digital-temperature-sensors/tmp36/products/product.html Fiche technique]
== Comment mesurer la température ==
=== Comment mesurer la température ===
Comment calculer la température
Comment calculer la température
Il faut donc convertir la tension analogique en degré.
Il faut donc convertir la tension analogique en degré.
Soit 50 degrés Celcius.
Soit 50 degrés Celcius.
si vous utilisez un LM35 ou similaire, la température se calcule comme suit (utiliser la ligne 'a' sur le graphique):
<nowiki>Temp en °C = ( Tension_de_sortie_en_millivolts) / 10</nowiki>
=== Utilisation de plusieurs senseurs ===
Vous pourriez rencontrer des problèmes si vous utilisez de multiples senseurs analogiques.
Problems you may encounter with multiple sensors:
If, when adding more sensors, you find that the temperature is inconsistant, this indicates that the sensors are interfering with each other when switching the analog reading circuit from one pin to the other. You can fix this by doing two delayed readings and tossing out the first one
Vous obtiendrez [http://www.adafruit.com/blog/2010/01/29/how-to-multiplex-analog-readings-what-can-go-wrong-with-high-impedance-sensors-and-how-to-fix-it/ plus d'information en lisant cet article] ('''en anglais''')
== Tester le senseur ==
Testing these sensors is pretty easy but you'll need a battery pack or power supply.
Connect a 2.7-5.5V power supply (2-4 AA batteries work fantastic) so that ground is connected to pin 3 (right pin), and power is connected to pin 1 (left pin)
Then connect your multimeter in DC voltage mode to ground and the remaining pin 2 (middle). If you've got a TMP36 and its about room temperature (25°C), the voltage should be about 0.75V. Note that if you're using a LM35, the voltage will be 0.25V
[[Fichier:TMP36-test.jpg]]
The sensor is indicating that the temperature is 26.3°C also known as 79.3°F
You can change the voltage range by pressing the plastic case of the sensor with your fingers, you will see the temperature/voltage rise.
[[Fichier:TMP36-test2.jpg]]
With my fingers on the sensor, heating it up a little, the temperature reading is now 29.7°C / 85.5°F
Or you can touch the sensor with an ice cube, perferrably in a plastic bag so it doesn't get water on your circuit, and see the temperature/voltage drop.
[[Fichier:TMP36-test3.jpg]]
I pressed an ice-cube against the sensor, to bring the temperature down to 18.6°C / 65.5°F
<small>Source: [http://learn.adafruit.com/tmp36-temperature-sensor AdaFruit]</small>
<small>Source: [http://learn.adafruit.com/tmp36-temperature-sensor AdaFruit]</small>