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Ligne 56 : − + − However, by default, the Arduino's {{fname|analogRead()}} use a 10 bit coding. So the range of possible value return by {{fname|analogRead()}} is 0 to 1024 (for 0 to 3.3v). This means that the accuracy of reading is 3.3 / 1024 = 0.0032 Volts, so 3.2 mV.+ − + + + + + + + + + + + + + − + + + + + + + + + + + + + + + + − + − + − * | Arduino − * | CIRC-10 .: Température :. − * --------------------------------------------- − * Un programme simple qui affiche la température − * actuelle dans la fenêtre de monitoring/débogage + + + + + + + + + + + + + + + + + + + + + + + + + − + − + − // sur laquelle la broche Vout du TMP36 est+ − // connectée. La résolution est 10mv/degré − // centigrade avec 500 mV de décalage/offset − // pour permettre la lecture de température − // négative. + − + − // Pour voir le le résultat, ouvrez le « moniteur série », le+ − // dernier bouton dans la barre d'outil.+ − // (celui qui ressemble à une boite ayant une antenne). − + − + + − + − + − + − + − + − + − + − Serial.println( analogRead(pin) );+ + + + + + + + + +
→High resolution reading
== Testing the sensor ==
== Testing the sensor ==
In the both case, the measured would be identical.
In the both case show here under, the measured temperature would be identical.
{{ambox|text=However, if your project does need a high resolution analog reads then it may be appropriate to explore the "High Resolution Reading" example.}}
As the M0 does have an Analog-to-digital converter with a precision of 12 bits, we could also use the {{fname|analogReadResolution( 12 )}} to upgrade the {{fname|analogRead()}} resolution to 12 bits. In such case, the range of possible value return by {{fname|analogRead()}} is 0 to 4095 (for 0 to 3.3v). This means that the accuracy of reading is 3.3 / 4095 = 0.000805 Volts, so 0.805 mV.
By default, the Arduino's {{fname|analogRead()}} use a 10 bit coding. So the range of possible value return by {{fname|analogRead()}} is 0 to 1024 (for 0 to 3.3v). This means that the accuracy of reading is 3.3 / 1024 = 0.0032 Volts, so 3.2 mV.
As the M0 does have an ADC (''Analog-to-Digital Converter'') with a precision of 12 bits, we could also use the {{fname|analogReadResolution( 12 )}} to upgrade the {{fname|analogRead()}} resolution to 12 bits. In such case, the range of possible value return by {{fname|analogRead()}} is 0 to 4095 (for 0 to 3.3v). As we have a real 12bit ADC, we can rely on that accuracy (it is not a 10 bits ADC storing the data into a 12 bits integer).
with 12bits we have an reading accuracy of 3.3 / 4095 = 0.000805 Volts, so 0.805 mV.
=== Low resolution reading ===
=== Low resolution reading ===
<syntaxhighlight lang="c">
// where is wired the TMP36
const int temperaturePin = A3; // analogue input
// Executed once when starting the microcontroler
void setup() {
// start serial connexion with the computer
Serial.begin(9600);
}
=== High resolution reading ===
// Executed again and again
void loop() {
// read the voltage of TMP36
float voltage = getVoltage(temperaturePin);
Serial.print( "Voltage : " );
Serial.print( voltage );
Serial.println( " Volts" );
// convert voltage to temperature
// Degrees = (voltage - 500mV) multiplied by 100
float temperature = (voltage - .5) *100;
Serial.print( "Temperature: " );
Serial.print(temperature);
Serial.println( " °C" );
Serial.println( " " );
delay(1000); // wait 1 second
}
/* ---------------------------------------------
/*
* | Code d'exemple du kit d'expérimentation
* getVoltage() - return the voltage of an analog pin
*/
*/
float getVoltage(int pin){
// AS the sketch does not call the analogReadResolution()
// function to change the analog reading resolution
// THEN Arduino use the defaut 12 bits resolution!
// Under 12 bits resolution, the analogRead() returns
// a value between 0 & 1024.
//
// Convert digital value between 0 & 1024 to
// voltage between 0 & 3.3 volts.
// (each unit equal 3.3 / 1024 = 3.2 millivolts)
return (analogRead(pin) * .0032);
}
</syntaxhighlight>
Once the sketch uploaded to the board, you can start the Serial Monitor
[[Fichier:ENG-CANSAT-BMP280-04.png]]
Which produce the following result on the Serial Monitor
[[Fichier:ENG-CANSAT-TMP36-60.png|640px]]
{{ENG-CANSAT-TRAILER}}
=== High resolution reading ===
// Variable pour broche du TMP36
<syntaxhighlight lang="c">
const int temperaturePin = A3; // entrée analogique
// where is wired the TMP36
const int temperaturePin = A3; // analogue input
// Executed once when starting the microcontroler
void setup() {
void setup() {
Serial.begin(9600); // Démarrer la connexion série avec l'ordinateur.
// start serial connexion with the computer
Serial.begin(9600);
// Upgrade the ADC resolution from 10 to 12 bits.
analogReadResolution( 12 );
analogReadResolution( 12 );
}
}
void loop() { // s'exécute encore et encore
// Executed again and again
// Acquérir la tension lue sur le senseur de température.
void loop() {
// read the voltage of TMP36
float voltage = getVoltage(temperaturePin);
float voltage = getVoltage(temperaturePin);
Serial.print( "Voltage : " );
Serial.print( "Voltage : " );
Serial.print( voltage );
Serial.print( voltage );
Serial.println( " Volts" );
Serial.println( " Volts" );
// conversion de 10mV par degré avec un décalage (offset) de 500 mV.
// convert voltage to temperature
// Degrés = ((tension - 500mV) fois 100)
// Degrees = (voltage - 500mV) multiplied by 100
float temperature = (voltage - .5) *100;
float temperature = (voltage - .5) *100;
Serial.print( "Temperature: " );
Serial.print( "Temperature: " );
Serial.print(temperature); //affiche résultat
Serial.print(temperature);
Serial.println( " °C" );
Serial.println( " °C" );
Serial.println( " " );
Serial.println( " " );
delay(1000); // Attendre une seconde.
delay(1000); // wait 1 second
}
}
/*
/*
* getVoltage() - retourne la tension d'une entrée analogique identifiée par 'pin'
* getVoltage() - return the voltage of an analog pin
*/
*/
float getVoltage(int pin){
float getVoltage(int pin){
// Convertir valeur digital de 0 à 4095 vers une valeur entre 0 et 3.3 volts.
// Convert digital value between 0 & 4095 to
// (chaque unité lue vaut ~ 3.3 / 4095 = 0.805 millivolts
// voltage between 0 & 3.3 volts.
// (each unit equal 3.3 / 4095 = 0.805 millivolts)
return (analogRead(pin) * .000805);
return (analogRead(pin) * .000805);
}
}
</syntaxhighlight>
Once the sketch uploaded to the board, you can start the Serial Monitor
[[Fichier:ENG-CANSAT-BMP280-04.png]]
Which produce the following result on the Serial Monitor
[[Fichier:ENG-CANSAT-TMP36-70.png|640px]]
{{ENG-CANSAT-TRAILER}}
{{ENG-CANSAT-TRAILER}}