Week 11

## Group assignment:

• Probe an input device's analog levels and digital signals

## Group 1

• Cristian Loayza
• Silvana Espinoza
• Jose Alberto Rodriguez
• Maria Angela Mejia
• Hans Moncca
• Maryori Vasquez

• ## Group 2

• Renson Samaniego
• Wilber Giron
• Ronal Vilca

• Grace Schwan
• Jorge Pazos

• ## Group 1:

### Hans Moncca Contribution

#### PROBE AN INPUT DEVICE'S ANALOG LEVEL AND DIGITAL SIGNALS

##### TIME OF FLIGHT ANALOG LEVEL

For the group assignment, we met with my colleagues from FAB LAB PERÚ and we will carry out the measurements of the analog level and 2-input digital signal that we chose. First we will work with the Time of Flight Distance to see the analog level behavior and then we will try with a switch that turns on an LED as a digital signal. The tool we will use is the DS213 oscilloscope that we have at the FAB LAB UCSUR.

• In the first test we perform an analysis in milliseconds of the frequency, where we begin to analyze in AUTO with 10 mS. Where we can see in the photograph that the frequency difference between the highest level and the lowest level is 15.3 mS. In addition, we analyze the voltage and we can see that between one wave and another there is 4.48V that passes, we can see this at the bottom of the oscilloscope.
• For the second test, we modify the time level to 2uS as can be seen in the photograph and we can see that the difference in the frequency of the wave is 1.93 uS between the highest level it reaches and the lowest level. This is when we are making contact with the SCL PIN of the sensor.
• Then, by switching to the SCL PIN, we can see that the oscilloscope presents other data. Where we can see that the wave changes and the frequency has a difference of 9.33 mS between the highest part of the wave and the lowest part of the wave.
• Here is a video of how we measure the analog level of the time of flight distance sensor when it is working. Here we can see the difference when we make contact with one of the sensor information pins.
• ##### DIGITAL SIGNALS - SWITCH

For the group assignment, we met with my colleagues from FAB LAB PERÚ and we will carry out the measurements of the analog level and 2-input digital signal that we chose. First we will work with the Time of Flight Distance to see the analog level behavior and then we will try with a switch that turns on an LED as a digital signal. The tool we will use is the DS213 oscilloscope that we have at the FAB LAB UCSUR.

• To obtain the digital signals, we wanted to practice with an LED and a SWITCH that makes the LED turn on when pressed. Here we can see the process of the digital signals that the oscilloscope reads to understand the operation of these components.
• Then, we tried to measure the frequency they had between digital signals 0, that is, the lower part. Here in the photograph we can see the white lines that we can use on an oscilloscope to obtain the exact data.
• Finally, we also made contact on the LED while it was on and we were able to obtain the data we need thanks to the oscilloscope. In time, we have approximately 7.33 uS of time between signal and the voltages vary from 0 to 3.41V. Here we can understand how digital signals work and see that when we turn on an LED, for example, the digital power signal "1" is activated and then drops to "0".
• Here is a video of how we measure the analog level of the time of flight distance sensor when it is working. Here we can see the difference when we make contact with one of the sensor information pins.
• ##### CONCLUSION

One more week of teaching and a lot of practice to understand a very complex world like electronics. This week I can conclude that I learned a lot about digital and analog signals. Now I understood the difference much more and we can see them in a "real" way on instruments like the oscilloscope. Finally, I can conclude that we must take into account that each INPUT has its characteristics and know if it is DIGITAL or ANALOG. From there, we can understand how it works, connect to the correct PINS of our microcontrollers to make better use of them and ensure they function better. Here is a group photo with my FAB LAB colleagues, each with the inputs seen and reviewed for the week.

##### March 23

We went to UCSUR (Universidad Cientifica del sur), we all started to see what sensors we have, we saw how they work, each one brought his programming for his sensor and we could do the tests.

• Maria Angela was programming the soil moisture sensor, she had many problems with the programming, it took half a day to understand how it worked.
• Hans was setting up the oscilloscope to start measuring the sensor signals.

• We seek to see the best signal. and we were able to have graphs that were within what was expected

## - Ronal Noel

### Ronal Vilca Apolin

This week, we carried out group work in which each team member used their own sensors, maintaining an online connection throughout the process. We used the Zoom platform to meet, which allowed us to discuss and carry out tests with different sensors. In my case, I focused on the turbidity sensor and we were able to work collaboratively to obtain effective results.

To analyze this data, we performed the test using the Arduino IDE development environment and the following code, as part of our first job.

### Code

These are the results we obtained after uploading them to the XIAO, which allowed us to perform a more detailed analysis of the collected data.

### Photoresistor

An exciter or photoresistor is an electronic component whose resistance changes (normally decreases) with increasing intensity of incident light.1 It can also be called a photoconductor, photoelectric cell or light-dependent resistor, whose acronym, LDR, originates from from its English name light-dependent resistor. Its body is made up of a photoreceptor cell and two pins. The following image shows its electrical symbol.

Its operation is based on the photoelectric effect. A photoresistor is made of a high-resistance semiconductor such as cadmium sulfide, CdS. If the light incident on the device is of high frequency, the photons are absorbed by the elasticities of the semiconductor giving the electrons sufficient energy to skip the driving band. The resulting free electron and its associated hole conduct electricity, thereby decreasing resistance. Typical values ​​range from 1 MΩ or more in the dark to 100 Ω in bright light.

### Component Inventory

• Motherboard for the Xiao
• Xiao RP2040
• Photoresistor Sensor

The next step involves uploading the code that interprets the sensor values, allowing us to obtain accurate readings and better understand the data collected.

### Case 1

We continue reading the sensor values. As a first measure, we cover the sensor with our hand and then observe the results on the serial port.

### Case 2

On this occasion, I provided direct illumination to the LDR sensor, which will allow you to clearly see the marked difference in the data collected.

The following image shows a sequence of chart data collected by the Serial Plotter.

"It was a tremendously productive week, as as a Fablab Peru team, my colleagues Grace, Wilber, Renso and myself had the opportunity to experiment with a variety of sensors. We each shared our individual experiences, thus enriching our collective knowledge ".