9. Input devices: Angel, Zaina¶
Group Assignment¶
Probe an input device’s analog levels and digital signals¶
Analog Levels - Angel Fang¶
For meaasuring analog levels, we used the oscilliscope.
We used the circuit that involves an LED and a touch capacitive sensor. When I touch the sensor, the LED will light up.
We connect the red wire on the voltage pin and the black wire of the oscilliscope onto the ground pin. There is an additional wire that is connect t the signal pin of the circuit.
Here is a video of the signal the oscilliscope detected.
The touch signal interrupt the current and would signal higher than the normal current.
In order to make the signal more clear, we chnaged the mode and make all the signal like a line.
When I did not touch the sensor, the whole signal is like a continuous line. Then when I touched the sensor, the line would lift up because of the higher signal it receives.
Digital Levels - Zaina¶
Touch Detection¶
We first attached a touch sensor to an RP2040 using jumper wires and an LED. The sensor detects a change in capacitance (your body adds capacitance). The microcontroller interprets this through a touch sensing pin or a digital signal from a touch module as a “touch event.” When it detects a touch event, it turns the LED on. When there’s no touch, it keeps the LED off.
Image of Wiring
Voltage Behavior¶
We attached the 2 nodes of the voltmeter to the ground and powered on the LED. Low voltage: ** 0V when the sensor is untouched. High voltage: ** 3.3V or 5V When the sensor is touched. We noticed that the voltage was about 3.3V
Video