A temperature sensor ( range 0°C to 150°C ) with +10 mV/°C Scale Factor is connected with 10 bit ADC is placed in a room. Calculate the digital output when the room temperature reaches 68°C.
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Answer:
i'm using pic16f877 to get temperature values from a LM35 temperature sensor. The ADC output is an 8-bit signal, therefore the resolution should be 255(2p8-1). Here comes the formula for calculating the temperature: T=5*ADC*100/255. I got the values which seemed to be temperature values such as 20, 21 or something. But I think there should be a problem with that formula. Since the signal is an 8-bit data(0 to 255). If I've got an ADC value 255, the temperature will theoratically be 500, no problem with it, but what about temperatures below 0. What ADC values should corrspond to these temperatures? Could anyone give me an explaination?
Many thanks!
By the way, there are 3 pins on LM35, 2 for power supply, the final one is signal pin. I connected this pin to the ADC channel on the PIC16F877 board.