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| | | |
| == 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. |
| | | |
− | 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. | + | {{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.}} |
| + | |
| + | 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). | | 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). |
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| === 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); |
| + | } |
| + | |
| + | // 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 |
| + | } |
| + | |
| + | /* |
| + | * 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 === | | === High resolution reading === |
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| } | | } |
| </syntaxhighlight> | | </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}} |