Adafruit Temp Sensor Tutorial

Measuring temperature with a beaglebone black.

Adafruit temp sensor tutorial.

Send real time analog sensor data to adafruit io. Wide range low power temperature sensor outputs an analog voltage that is proportional to the ambient temperature. Its very similar to the lm35 tmp35 celsius output and lm34 tmp34 farenheit output. They work great with any microcontroller using standard i2c.

Using a tmp36 temperature sensor with beaglebone black by simon monk. Temp in c vout in mv 10. Temp in c vout in mv 500 10. If you re using a lm35 or similar use line a in the image above and the formula.

Tutorials and series to get you on your way. A thermistor is a thermal resistor a resistor that changes its resistance with temperature. Technically all resistors are thermistors their resistance changes slightly with temperature but the change is usually very very small and difficult to measure. Since the raspberry pi has no adc analog to digital converter it cannot directly use an analog temperature sensor like the tmp36 making the ds18b20 a good choice for temperature sensing.

Reading temperatures to 0 1 degree precision. Additionally because the pct2075 allows the address pins to work in three states high low floating you can have 27 pct2075s on the same bus as. Voltage at pin in millivolts reading from adc 5000 1024 this formula converts the number 0 1023 from the adc into 0 5000mv 5v. To use connect pin 1 left to power between 2 7 and 5 5v pin 3 right to ground and pin 2 to analog in on your microcontroller.

Thermistors are made so that the resistance changes drastically with temperature so that it can be 100 ohms or more of change per degree. These stats are for the temperature sensor in the adafruit shop the analog devices tmp36 40 to 150c. The voltage out is 0v at 50 c and 1 75v at 125 c. To convert the voltage to temperature simply use the basic formula.

So for example if the voltage out is 1v that means that the temperature is 1000 mv 500 10 50 c. Compared to the lm75 however the 11 bit adc in the pct2075 provides more precise measurements when compared to the lm75 s 9 bit adc. If you re using a 5v arduino and connecting the sensor directly into an analog pin you can use these formulas to turn the 10 bit analog reading into a temperature.