Electronics Design

My experience

First step

Remembering week 4 of the Fab Academy (click here), thanks to those first explorations and those first investigations about the beginning or the basis of electronics I was able to have a better understanding of this process, this week we are asked to design our own board, solder it and program it. The steps to do it are many but the first thing you must have is the necessary components and the tools you are going to use, here is the list that I needed for my first test: ✔️

Components:

1. USB
2. Zócalos
3. ATtiny85
4. Res68 ohms
5. Res270ohms
6. Leds
7. Boton
8. Baquelita

Tools:

1. Cautin
2. Estaño
3. Pinzas
4. Pasta de soldar
4. Desoldador

What I got

Here in Lima I was able to get the necessary components in a store in the center of the city, they are not so cheap but not so expensive either. Thanks to my partner Hayashi Mateo we made a single purchase to avoid going several times so it is advisable in a pandemic context to avoid going out the least amount of times to get anything. In total I spent an average of 40 soles for all my kit for this assignment. 😃

Exploring

Thanks to the support of a classmate's parents we got to know an old oscilloscope, I had never seen one before and even less such a big one, it was very interesting to know how it works and how to manipulate it, unfortunately we could not complete our task because something was wrong with its operation, but it was still a nice experience.


In the lab we got together to make an oscilloscope. An oscilloscope is an electronic display instrument for the graphical representation of electrical signals that can vary over time. It is widely used in signal electronics, often in conjunction with a spectrum analyzer. Thanks to our colleague Hayashi Mateo who is an Mechatronics engineer we were able to solve the assignment together, the only thing we needed was an ARDUINO UNO and a laptop to be able to do the test, the only restriction was that it could only recognize up to 5 volts, anyway it was interesting to see how we can solve something in a homemade way despite not having a machine. 👏

Working

As a first step I needed an arduino nano, some jumpers, my board and the help of my mother and my sister, they supported me in holding the wires to show the video you will see below. 🥰





To get that graphic on the screen I used the Arduino ISP, this is a program that you can download from the official Arduino website. (click here) The arduino ID has 3 parts, global part (sensor), void setup (pins - serial) and void loop (functions that are going to be repeated). As I need communication between my display and the arduino nano I activate the serial function, bi-directional communication, then I used a code in the three parts that I will show in the pictures.



Finally as we already have our program ready to respond I place two jumpers, together the negative with the GND of the arduino and the positive with the A0, this to respond our graph, then you can see how the figures change on our screen, it was very interesting to know this whole process and above all make it real. 💪🥰

First attempt

In my case, since I already had my first board soldered, I used it to test the programming. The first thing is to get the USB input to solder it together with the pins and connect them, here I show the images of this process. 🙂


As a next step I needed to test that there was no short, otherwise it could be detrimental to my laptop usb port. For this I had to create a kind of tester, I don't have a multimeter at home so I made one myself. To build a tester you only need a led, a resistor, two wires (negative and positive) and a source, in my case I recycled an old cell phone charger and soldered it. This allowed me to foresee any inconvenience in my board, below I show what happened.

Second attempt

The result was not good, 😢 my board was shorting out, this needed to be repaired before any further steps. At first glance my soldering was not good and since my board was not completely clear of copper it made it more difficult. One recommendation is not to have the board like mine because at the moment of soldering you need too much precision, for us beginners it is not a good idea so as I didn't have the machine at home I had to do a copper clearance by hand on my second board.



Before soldering the ATtiny 85 I did the programming on my computer, this will be useful for when I connect my board with the USB input and I can recognize it. To do this I used FABINO, an arduino trainer that contains different components that helps me to make simulations and I used it in week 4 to start learning about electronics. Next I will show the steps for programming the ATtiny 85. ✔️



To get the programming I needed to download the ARDUINO 🙂 program from its official website (here) and download some folders to install the drivers (here). With this I followed a series of steps that I will explain below.



After getting the programming of ATtiny85 I had to solder it to my board, I was very careful with this soldering because the first time I did it I made a mistake in the orientation, I recommend to be very concentrated because otherwise there may be some details that not being fulfilled will spoil your whole process. 👌



The last step before connecting it to my computer is to do the current test, when this happened I realized that my board was short, I checked all possible connections and scraped them with my blade but it was still short. As a conclusion, after a long time, the problem was being my ATtiny, I tested it and it was burned. 😢 Here are the pictures.

Third attempt

On my third attempt I had to get another ATtiny for my plate, thanks to my partner Hayashi Mateo we were able to get the next day and continue with the next attempt. For this I had to remove once again the ATtiny and as I had put the soldering iron on it for a long time to change it, the copper started to come out. It was for this reason that I made use of my third plate, here I show some pictures.



After that I did the current test, all my components were correctly soldered (thanks to practice) and in particular it helped me a lot to use a socket because I think this protects a little more the ATtiny, for beginners like me I recommend to use it, just bend the legs at the base to solder it without problems. 💪



Apparently everything was going well, but my badge was not being recognized. This time I managed to see my LED light up and my computer beeped when I inserted the USB but it was telling me that the device was not recognized. What was going on? 😢



My first mistake was to solder this led resistor in another place, I had to correct it. After that I did the tests with the leds and the continuity between the traces. 🥵


Since there was a short between paths 1 and 4 and I still couldn't make the connection I made some new ways to solve my board. This board was much better soldered and I didn't want to mess it up so I fought to the end to make it work!

Finally

In order to finish with the functionality of my board I had to do three things, as there were still traces that shorted I had to use an external cable in the connection between pin 4 and trace 4 (because the current did not arrive), cut the track 4 to connect it with a copper wire (since a small part of the trace was not working either) and change the resistance of the green led because when I connected it to my computer it did not turn on (this resistance apparently had burned). Next I show part of the process.


The next step was to do the programming with the arduino program, this was the acid test so I was very scared because it would be practically my last attempt. 🐵

New design

In this new opportunity I made a circuit from scratch considering now new components, now I know that it is very important to be very cautious when building the board. One of the things I will not do again is to use the thick soldering iron, that does not help at all. Here are some pictures of the design process.



After choosing my components and distributing them on the plan as you could see, I chose to design an interesting shape this time, I have seen conventional plates and shapes of all kinds but I never saw one that reflected a symbol of any culture in Latin America. So I chose The chakana, this is a millenary aboriginal symbol of the indigenous peoples of the central Andes in the territories where both the Inca culture (southern Colombia, Ecuador, Peru, western Bolivia, Chile and Argentina) and some pre-Inca cultures (Peru and Bolivia) developed. Also called Andean Cross, it is a recurrent symbol in the original cultures of the Andes and its shape is that of a square and staggered cross, with twelve points. To start I used Inkscape and took the basic shape of this symbol, then I imported it into Easy EDA and used it to build the border of my plate. 🥰



Once the design was ready I made use of two more programs, FlatCAM and CNCjs, both help me to process the files generated from EasyEDA, below I share some images. The machine I use is called Roland Modela MDX - 20 and now that it is back in the lab I was able to test my board.



I really liked this work, designing something and then having it in your hands gave me a very nice feeling, everything we do these weeks are events that result from our own work and that's a very good thing. Here I share some final photos of the shape of my Electronic Chakana.

Electronic Chakana

Electronic Chakana

Update

Since my board did not present all the complete circuits because our MDX 20 modeling machine has a strange operation, when we send to cut, it reduces part of the board and eats some paths already milled, the solution I gave was to move my design in EasyEda and allow more space to my circuits.

Electronic Chakana

New season

After my first exploration, and as part of the design process, I decided to start making my final project board, for this exercise I decided to integrate as many pins as possible, this in order to allow connecting many types of sensors for the following weeks. Thanks to the work of Adrian Torres, I could understand that this would be possible so I was guided by his Adrianino board and used it as a reference, definitely his work has facilitated my understanding of this part of the diploma.

Below I will show the step by step of my design and the manufacturing process it went through.

My project flowchart

First it was important to decide the functionality that my final project was going to have, as I have already mentioned before, my project is aimed at children, it is interactive and over time has been transforming its purpose. To begin with it was necessary to consider an input sensor that would allow me a first interaction with the user, in this case, I will use the infrared sensor, and to achieve a response from the device, I have decided to connect a motor that allows me to perform movement.

To achieve all this, I have first determined the main flowchart of my project, in electronics, a flowchart refers to the logical or sequential path of signals, energy or data within an electronic system. This concept is applied to describe how components interact and work together to accomplish a specific purpose.



Once the diagram is understood, it is time to choose the necessary components. For this I have decided to work with an ATtiny1614 microcontroller, here I share the list:

Components:

1. Microcontroller: ATtiny1614: Main microcontroller that controls the operations of the system.
2. Voltage regulator: VR_REGULATOR_SOT223: To stabilize the power supply to the electronic components.
3. MOSFET transistor: IRFZ44ZPBF: Used to control loads such as motors or LEDs.
4. Optocoupler: 4N35M: Provides galvanic isolation between circuits.
5. Capacitors: 1uF, C2: Used to filter and stabilize power supply.
6. Resistors: (R1, R2, R3, R4, R5, etc.), used to limit current, adjust signals, or implement voltage dividers.
7. LEDS: LEDFAB1206: LED that functions as a visual status indicator.
8. Switches or buttons: SPDTSWITCH: Switches used to activate or configure the system.
9. Connectors: Pins or connectors for interfacing external modules or peripherals.
10. Communication pins: SDA and SCL: For I2C communication. TX and RX: For UART communication.
11. Jumpers
12. Protection diodes

ATtiny 1614

The ATtiny1614 is an 8-bit microcontroller from the AVR family, ideal for small and medium-sized projects due to its low cost and versatility. It offers 16 KB of Flash memory, 2 KB of SRAM and 128 bytes of EEPROM, with a speed of up to 20 MHz. Its 14 GPIO pins are configurable, and it has peripherals such as 10-bit ADC, PWM, I2C, SPI and USART for communication. It is also power efficient, with low-power modes, and is easy to program with environments such as AVR GCC or Arduino IDE. It is an excellent choice for compact and inexpensive devices, with applications in device control, sensors, and IoT projects.



Okay, once I had chosen my project flow and components, I decided to try a new board design program; EAGLE.

EAGLE

EAGLE (Easily Applicable Graphical Layout Editor) is Autodesk's software for designing printed circuit boards (PCB) and electrical schematics. It is widely used by amateurs and professionals due to its intuitive interface, powerful tools and extensive component library. It allows creating schematics, designing multilayer PCBs, routing traces manually or with autorouter, and verifying the design through DRC (Design Rule Check) and ERC (Electrical Rule Check). It generates files compatible with PCB manufacturers and integrates with Fusion 360 for mechanical designs. Although its free version has limitations, it is ideal for projects of any size, thanks to its flexibility and community support.

Connectors

In this configuration, I am using both a UPDI connector and an FTDI SparkFun Basic Breakout, each with a specific purpose to optimize the functionality of my board.
The UPDI (Unified Program and Debug Interface), which looks like a manually crafted core connector, I am connecting to the board so that I can program and debug the ATtiny1614 microcontroller. This modern microcontroller uses the UPDI protocol as its primary programming and debugging method, making it essential for loading firmware and making adjustments in project development. This UPDI connector uses three pins: VCC for power, GND as common ground and the UPDI pin, which allows to establish direct communication with the microcontroller to transfer programs or monitor its behavior in real time.

On the other hand, I am also using the FTDI SparkFun Basic Breakout, a module shown on the left of the following image. This I connect to my board to handle the serial communication between the microcontroller and the computer. Through the TX and RX pins, I can send and receive data, which is critical for monitoring the state of the system or interacting with it as it runs. In addition, this module facilitates initial programming in systems that do not yet have the UPDI configured or where an additional serial connection is required for monitoring or testing. The FTDI's DTR pin also allows the microcontroller to automatically reset, streamlining the workflow during development.

I am using both connectors in my design to take advantage of the unique capabilities of each: the UPDI for programming and debugging the ATtiny1614 and the FTDI for establishing serial communication and real-time testing. This combination allows me to work efficiently at all stages of development, from loading the firmware to interacting with and monitoring the live system.




My board is ready! Now that I got it soldered and connected to my computer, I did a continuity test to see if it is powered up correctly. Next I started to configure step by step to get the system working.

And finally I performed the led test on my own board, and it worked!


My electronic board is now operational! It's time to start testing all its features, see you next week!.

Download the files here

UPDI interior
UPDI traces
Ottino move board
Ottino move schematic