Input Devices¶
Group assignment requirements¶
The group assignment for this week is the following:
- Probe an input device(s)’s analog levels and digital signals
- Document your work on the group work page and reflect on your individual page what you learned
Analog Signals¶
Sensor¶
The selected sensor is a [Light] sensor. Find the datasheet here. It is an analog sensor which means that the voltage changes based on it’s measured value.
Light sensor that the incident light on its surface will change the resistivity of the sensor.
Observed signals¶
change the below connection to the way you connected your sensor
Connection:
Sensor VCC pin > [power supply 3.3V]
Sensor signal pin > [Multimeter positive terminal]
circuit GND pin > [Power supply negative] > Multimeter negative pin
To observe the operation of this sensor, we probed it with a multimeter to showcase the change of output voltage depending on [light intensity]
The values shows the change in the voltage as the incident light changes, so when the light are full intensity on the surface of the sensor the sensor resistivity will be the minimum and when the incident light is the minimum on the sensor surface the resistivity of the sensor will be maximum.
Digital Signals¶
DHT 22 (AM2302)¶
The selected sensor is a [Temperature] sensor. Find the datasheet here. It is a digital sensor which means that its voltage changes between 0 volts and [3.3]volts
This sensor is a digital sensor able to measure both Temperature and humidity.
Connection¶
change the below connection to the way you connected your sensor
Connection:
Sensor VCC pin > [Microcontroller 3.3V]
Sensor GND pin > [Microcontroller GND] > oscilloscope negative terminal
Sensor Signal pin > [microcontroller pin 8] > oscilloscope positive terminal
To observe the operation of this sensor, we probed it with a oscilloscope to showcase how its signal changes from 0 to 1 based on external factors
The values are not clear when it comes to reading it by eye because it just some periodic signal goes up and down but when we consider it carefully we will notice that the peak of each line in the signal and the frequency of the signal it self are changing according to the physical quantity measured by the sensor.