That is we need to decrease the value read on output by 0.5 V. Because this is an imperfect device, an error voltage needs to be subtracted from the voltage reading. Theoretically the lowest voltage output would be 0 volts and the highest is 3.3 V. If the sensor experiences a change of 100☌, the output of the device will change by 1 Volt or 1000 mV. The TMP36 device reports a 10 millivolt change for every 1☌ change. What happens to the values printed to the screen? Why does this happen? Gently grasp the TMP36 with your thumb and index fingers. How does the Raspberry Pi know which sensor is which?Ħ. How does the MCP3008 know which sensor is which?ĥ. Print("The TMP digital value is", adc1.value)Ĥ. Print("The value on the photoresistor is",adc0.value) Save this file with IoT_08_program2.py as the filename. Task 5: Measure light and temperature sensor values.įor this task, enter and execute the following program with your Thonny IDE on your Raspberry Pi.
![analog to digital converter card analog to digital converter card](https://www.analog.com/-/media/analog/en/category/spotlights/precision-adc-20msps/ad4111-chip.png)
The current draw is very low which means it only raises observed temperature by less than 0.1☌. The device doesn’t need external callibration to provide accuracy of ☑☌ at room temperature, and ☒☌ over the operating range of -40☌ to +125☌. The sensor uses a heat sensitive diode that changes the voltage the analog V OUT voltage allowing us to measure temperature. The voltage output is linearly proportional to the celsius temperature. The TMP36 is a low power temperature sensor that outputs an analog signal. Change your python program above to contain an IF statement that prints “Hey, who turned off the light?” if you place your hand over the sensor. Does output indicate diffences in light hitting the sensor?ģ. If your circuit is built correctly, you should have values of near 1 for when there is no light hitting the sensor (place your hand over it), and near 0 when there is ample light (shine a flashlight or your phone light).
#Analog to digital converter card code#
What does each line of code above tell the raspberry pi to do?Ģ. The value argument for MCP3008 returns a read value from the device scaled to a value between 0 and 1. Save this file with IoT_08_program1.py as the filename.
![analog to digital converter card analog to digital converter card](https://cool.culturalheritage.org/videopreservation/dig_mig/images/BmD_multibridge_Pro-back.jpg)
\( \newcommand\): Photo transistor light sensorįor this task, enter and execute the following program with your Thonny IDE on your Raspberry Pi.