Raspberry pi pico

Main characteristics

• Dual-core Arm Cortex-M0+ processor, flexible clock running up to 133 MHz
• 264KB of SRAM, and 2MB of on-board flash memory.
• USB 1.1 with device and host support.
• 26 × multi-function GPIO pins.

from:

pico 1 documentation

Some terms definitions (from Wikipedia)

• UART: A universal asynchronous receiver-transmitter is a peripheral device for asynchronous serial communication
• GPIO: A general-purpose input/output (GPIO) is an uncommitted digital signal pin on an integrated circuit or electronic circuit (e.g. MCUs/MPUs) board which may be used as an input or output, or both,
• ADC: Analog-to-digital converter is a system that converts an analog signal into a digital signal.
• SPI: is a de facto standard (with many variants) for synchronous serial communication, used primarily in embedded systems for short-distance wired communication between integrated circuits.

For testing I used Arduino IDE and included a blink led code in C++ from the basic scripts Arduino provides.

Xiao ESP32 S3

The Xiao ESP32 S3 sense is a powerful little (21 x 17.8mm) micro controller.

Characteristics

• Xtensa LX7 dual-core, 32-bit processor that operates at up to 240 MH
• 11 + 2 GPIO pins.
• Complete 2.4GHz Wi-Fi subsystem and.BLE: Bluetooth 5.0, Bluetooth mesh
• OV2640 camera and digital microphon.
• Microphone
• On-chip 8M PSRAM & 8MB Flash
• SD card slot for external 32GB FAT memory
• USB-C enabled
• Average power consumption: 5V
• Working temperature: 40°C ~ 65°C

Some diagrams for the ESP32S3 sense follow.

A more detailed schema of the board can be found below:

In case you are looking for the user led for this model, thanks to Pablo from FL Leon I went to look harder for this. You can find it in diagram below.

Another well documented page for this controller developed by the DroneBot Workshop is provided below.

I found this micro controller in AliExpress for 15.99 euros so it quite affordable.

Testing

As I had already used C++ through the Arduino ID for this week I wanted to use something different. For this purpose I installed the IDE Thonny and uploaded the firmware to the board, you can see the documentation for this in my individual assignment if you need it. The library esp32 has the function **mcu_temperature()** that allows you measure the board temperature. As you can see you can run interactively python command in the console of Thonny.

And I also tested a blink the user led program.

i = 0;
from machine import Pin
from time import sleep 
led_pin = 21
led = Pin(led_pin, Pin.OUT)
for i in range(10):
  led.on()
  sleep(1)
  led.off()
  sleep(1)
  print("Blink",i+1)

For this week’s Group Assignment , we explored the design rules of multiple 3D printing technologies, with the Prusa mini, Bambu A1 Mini and resin printing (SLA). The goal was to understand how different printers and materials handle overhangs, wall thickness, bridging, infill, and support structures.

3D Extrusion Printers

Some important printer characteristics can be found below:

• Nozzle diameter: will impact the layer thickness of the material being deposed. The tip of the noozle also pushes the material being extruded. The layer should not be larger than the nozzle diameter. Nozzle diameters vary from 0.25 to 0.8mm.
• Working area: important to select the right area for the size of model you are building.
• Table positioning: can impact the attachment of the piece to the surface. Auto leveling helps control this.
  
• Chamber: a chamber is useful with materials that shrink when cooling which produce breakage if different parts of the model cool at different rates.
• Temperature: different materials might need different temperatures for being struded.
• Material extruder: whether is direct or bowden.

Slicer Characteristics

Some print characteristics that can be controlled through the slicer are:

• Layer height, however is related to the nozdle size.
• Infill percentage will determine the percentage of material inside the object being printed.
• Number of horizontal and vertical walls.

Nozzle diameter will affect the definition/detail on the horizontal plane while layer height will affect the detail on the vertical and slanted sides . As a rule of thumb layer height should not exceed 80% of nozzle diameter (Prusa’s blog).

https://blog.prusa3d.com/everything-about-nozzles-with-a-different-diameter_8344/

Nozzle horizontal plane definition(source=Prusa’s blog)

Layer height and definition(source=Prusa’s blog)

In addition to layer height a slicer will let you specify vertical and horizontal walls as number of layers. For the vertical walls in the image below subtract the shown vertical outside walls rom the walls above the purple surface which should give 3. It is adviced to have more top layers compared to bottom ones as the top will have only the infill for support which could cause the filament to drip contrary to the bottom wich is supported by the printer’s platform. In general the amount of material will vary between a functional print and a aesthetic one.

Similarly, one can specify infill as a percentage are the red layers (rhomboid shape) inside the cube.

Below you can find a picture of useful utensils that come handy with an extrusion printer.

Safety Guidelines for Extrusion 3D printing [in our lab]

Materials needed for operation

• Filament.
• IIsopropyl alcohol (>90%).
• Spatulas, forceps, cutting tools and tools to dislodge filament.
• Cleaning wipes

Personal Protective Equipment

• Depending on the material being printed you may need:
• Respirator
• Apron
• Gloves

Operation sequence

• Unload filament if a new one is to be used.
• Load filament and
• Purge the remaining filament
• Slice stl file and according to your application adjust for:
  • Vertical and horizontal walls
  • Infil
  • Material,
  • Nozzles size,
  • Temperature
  • Supports
  • Etc..
• Make sure it fits on the plate!
• Check your sliced object to make sure there are not problems
• Print G file and save it to a USB or send it throught wifi depending on the printer.
• Keep an eye from time to time on the printer
• Collect your print and clean the area.

Operation Precautions (People)

• Be aware of the characteristics and safety guidelines of the materials you are using.
• Use filaments that correspond to the printer settings and if possible use ones that have lower emissions.
• Operate the printer in a well ventilated place.
• Avoid standing close to the printer for long periods of time.
• Be careful if you use alcohol to clean the printer’s plate as it is highly flammable.
• Avoid touching heated platforms or hot nozzles.
• Wash your hands after/before utilizing the printer
• Disconnect the printer if changin/repairing printer pieces to avoid electric shock.

Operation Precautions (Machines)

• Clean the machine’s plate with alcohol after each print in order to avoid grease build up.
• Use appropriate filaments with their correct settings.
• Avoid build up of dust as this increases.
• If you change a nozzle make sure you update your slicer settings.
• Let the model print cool down before removing it from the printer’s platforms.
• Clean the work area thoroughly when finished.
• Dispose residual filament appropriately.

Our Lab Safety Guidelines for Extrusion Printing

Prusa Mini

Below you can find a diagram of the Prusa Mini from:

https://help.prusa3d.com/article/glossary-mini_125081

From this article is important to note:

• 8-Main PTFE tube (Bowden-tube): leads the filament strand from the extruder into the print head/nozzle. Inspect it from time to time to make sure there is no debris inside that would prevent the filament strand from reaching the nozzle.

• 10-Print fan: cools the printed object, and improves print quality. Comes with RPM monitoring.

• 11-Print head: Lightweight print head consisting of the hotend (printing nozzle), M.I.N.D.A. sensor, and two fans. The heaviest parts of the extruder were moved onto the Z-axis tower to improve print quality.

• 14-Extruder / Extruder motor: as opposed to 3D printers like MK2 or MK3S, the extruder motor is not moving along the X-axis. Instead, it’s fixed on the side and pushes filament through the PTFE tube towards the print head.

which make the Prusa Mini is a bowden extruder. Bodwen extruders present the following pros and cons:

Pros: - Cleaner movements: as the extruder is not located in the printer head allowing faster movements and better print quality. - Larger build volume: as it allows for a smaller head carriage.

Cons: - Needs a more powerful motor. - Slower response times due to the distance between the print head and extruder. - Material complications flexible materials can bind or wear in bowden tubes.

from: https://all3dp.com/2/direct-vs-bowden-extruder-technology-shootout/

The slicer for the Prusa Mini was configured as:

with an infill of 15% and using the generic PLA setting for type of material.

Bambu A1 Mini (Q) - General Features

The Bambu A1 Mini (Q) is an advanced entry-level 3D printer that offers high-speed and high-precision printing with an easy-to-use interface. This model is designed to provide a seamless printing experience with minimal setup time.

The A1 Mini (Q) is an excellent choice for beginners and professionals alike, offering reliability and ease of use with features that make 3D printing more efficient and precise.

Key Features:

• Build Volume: 180 × 180 × 180 mm
• Nozzle Diameter: 0.4 mm (default), supports 0.2 mm and 0.6 mm
• Layer Height: 0.1 - 0.3 mm
• Extruder Type: Direct Drive for improved performance with flexible filaments
• Printing Speed: Up to 500 mm/s
• Acceleration: 10,000 mm/s² for ultra-fast movements
• Temperature: Max extruder temperature 300°C, heated bed up to 100°C
• Auto Bed Leveling: Uses LIDAR-assisted calibration for precise first-layer adhesion
• Multi-Color Printing: Compatible with the AMS (Automatic Material System) for seamless filament changes
• Filament Compatibility: PLA, PETG, TPU, ABS, ASA, and more
• Connectivity: Wi-Fi, SD card, and USB support
• Software: Works with Bambu Studio and third-party slicers

Bambu A1 Mini - Testing Results

Below are the results of various print tests conducted using the Bambu A1 Mini.

1. Wall Thickness Test

• Print Time: 23 min 38 s
• Observations: The print quality was excellent. Thin walls were well-defined, but the first three layers (0.1, 0.2, 0.3 mm) did not print due to slicer limitations. Most slicers establish a minimum threshold based on the nozzle diameter. If a feature is thinner than this threshold, it may be automatically omitted to prevent printing errors. Adjusting the extrusion width settings in Bambu Studio could help resolve this.

2. Bridging Test

• Print Time: 28 min 38 sec
• Observations: Bridges up to 5 mm were good, but at 9 mm and 10 mm, there was noticeable stringing and sagging.

3. Angle Test

• Print Time: 49 min
• Observations: Overhangs remained stable up to 30°. At 10° and 0°, noticeable imperfections appeared.

4. Tolerance Test

• Print Time: 54 min
• Observations: 0.1 mm tolerance fits well with a firm grip, similar to laser-cut fits.

Tested Infill Patterns

• Honeycomb: Excellent strength-to-weight ratio, ideal for structural parts but increases print time.
• Cross Hatch: Balanced strength and speed, useful for general-purpose prints.
• Adaptive Cubic: Optimized for strength while using minimal material, dynamically adjusts density.
• Cubic: Strong and efficient for load-bearing parts, faster than honeycomb.
• Octagram Spiral: Visually unique, flexible but weaker than the other patterns, suitable for aesthetic prints.

Understanding Electronic Testing & Measurement

Before diving into hands-on testing, it’s important to understand the essential concepts behind electronic diagnostics. Electronic circuits are built upon voltage, current, and resistance, and each component behaves differently under these conditions. Testing tools allow us to measure, visualize, and troubleshoot these properties effectively.

• Voltage (V)The potential difference between two points in a circuit, measured in volts (V). Essential for checking if a circuit is powered correctly.
• Current (A)The flow of electric charge, measured in amperes (A). It determines how much power is moving through a circuit.
• Resistance (Ω)Opposition to the flow of current, measured in ohms (Ω). Helps diagnose faulty components or incorrect wiring.
• Digital vs. Analog SignalsDigital signals - switch between HIGH (1) and LOW (0), while, Analog signals - vary continuously. Understanding this distinction is key when using logic analyzers and oscilloscopes.

Group Task Distribution

Exploring Test Equipment for Electronics Design

from machine import Pin
from time import sleep
on_pin = 4
pin = Pin(lon_pin, Pin.OUT)
for i in range(1200):
  pin.on()
  sleep(1)
  pin.off()
  sleep(1)
  print("on",i+1)

void setup () {
	Serial.begin(9600);
	delay(1000);
}
																	
void loop() {
	Serial.println("hello camila and alfredo!!!");
	delay(2000);
}
								

This week at Fab Academy, we focused on CNC machine safety, setup, and calibration to ensure proper operation before cutting. The session covered lab safety training, machine controls, tool selection, and materials.

🔧 Lab Safety Training

Before operating the CNC machine, it was crucial to complete a safety training session. The CNC milling machine is a powerful tool, and improper use can lead to injuries, tool breakage, or material damage.

Key Safety Considerations

Personal Protective Equipment (PPE)

• Safety glasses: Protect against flying debris.
• Hearing protection: CNC machines can be loud.
• No loose clothing, jewelry, or gloves: These can get caught in moving parts.
• Closed-toe shoes: Protect feet from falling tools or materials.

⚠️ Emergency Stop and Safety Protocols

• The Emergency Stop (E-Stop) button immediately halts all operations.
• Power failures or sudden machine malfunctions require a manual reset before resuming operations.
• Fire hazards exist when cutting flammable materials, so a fire extinguisher must always be within reach
• A first aid kit should be easily accessible in case of minor injuries.

CNC Machine Overview & Controls

For this assignment, we used the Fresadora CNC 1325, a mid-size CNC router equipped with an air-cooled 4.5 kW spindle, a vacuum bed.
Machine Components The main components of the CNC router include:

• Spindle: The motorized cutting tool, capable of reaching 18,000 RPM.
• Worktable: The machine features a vacuum table that helps secure materials during cutting.
• Linear Motion System: The X and Y axes move using a rack-and-pinion system, while the Z-axis is controlled via a ball screw drive.
• Control System: The DSP handheld controller allows the operator to move the spindle and set the zero position manually.

Setting the Home Position we must set the home position (machine zero):

• Move the spindle to the desired origin point (X, Y, Z).
• Use the DSP controller’s movement keys to fine-tune the positioning
• Set this point as the zero reference by pressing "XYZ Zero".
• Control System: The DSP handheld controller allows the operator to move the spindle and set the zero position manually.

Router bit

The choice of router bit determines the cutting efficiency and final surface quality. We tested several types of bits: Common Router Bits & Their Applications

• Spiral Upcut BitThis bit is great for removing material quickly and keeping the cut cool. It pulls the chips upward, which helps clear debris but can also cause rough edges on the top surface. It works best for plastics, soft metals, and deep cuts, where chip evacuation is important.
• Spiral Downcut Bit Unlike the upcut bit, the downcut bit pushes chips downward, leaving a cleaner top surface. This is ideal for wood, plywood, and laminates, where you want smooth edges on the visible side. However, it can trap chips in deeper cuts, which might generate heat and affect performance.
• Straight BitA straight bit cuts evenly in all directions, making it perfect for pocketing and simple profile cuts. It doesn’t create a pulling effect like spiral bits, which helps prevent material tear-out. This bit works well for MDF, softwood, and plastics when a clean and stable cut is needed.
• Compression BitA combination of upcut and downcut geometry, this bit is ideal for plywood and veneered materials. It pulls up from the bottom and pushes down from the top, leaving both surfaces clean and smooth. This makes it perfect for materials that tend to chip or splinter. Each of these bits has its own strengths, and selecting the right one depends on the material, the type of cut, and the final finish you want. By understanding their behavior, we can achieve cleaner cuts, faster production, and better overall results in our CNC projects.
• End Mill Designed for precision and high accuracy, end mills are commonly used in metal, acrylic, and composite materials. They provide smooth, controlled cuts and are great for detailed profiles and deep slots. Unlike typical wood-cutting bits, end mills have sharper edges and can handle harder materials.

Ensuring CNC Precisiong

Runout: Checking Tool & Spindle Accuracy

Before diving into machining, we performed a runout test directly on the CNC router to check if the spindle and tool were properly aligned. Runout happens when the cutting tool doesn’t rotate perfectly centered, causing wobbling. This can lead to inconsistent cuts, uneven slot widths, rough edges, and faster tool wear.
We ran a test by cutting parallel slots into the material at different feed rates and speeds to observe any variations in cut accuracy and edge finish. The image below shows the results, where we measured slot widths and noted speed settings. Our findings confirmed that runout on this CNC machine was minimal, meaning the spindle and collet were well-calibrated.

Dial Indicator Test

Why Did We Also Use a Dial Indicator?

Speeds and Feeds

Understanding Feeds, Speeds, and Chip Load

Chip Load Calculation Formula

The chip load is the thickness of the material removed by each cutting edge of the tool. Proper chip load values help ensure that the tool doesn’t overheat or wear out too quickly. We calculated our feed rate using the following formulas:

Feed Rate Formula:

Using these formulas, we adjusted our settings to maintain a balance—avoiding a feed rate that’s too slow (which could cause burning) or too fast (which could break the tool or create rough edges).

Feed Rate Table

Below is the feed rate table we used to determine the correct cutting parameters based on tool size and material.

If you’d like to reference or modify the calculations, you can download the feed rate spreadsheet here:

• Download Feed Rate Calculator
• Download test files - Runout + Speeds and Feeds

Vacuum Table & Sacrificial Board

Why Material Holding Matters? Before any CNC machining operation, one of the most critical steps is securing the material. If the workpiece moves, even slightly, during the cutting process, it can cause misalignment, rough edges, tool breakage, or even machine damage. To ensure stability, two common methods are used: vacuum hold-down systems and sacrificial boards.

How the Vacuum Table Works

A vacuum table uses negative pressure to hold down the material during machining. The principle behind it is simple: atmospheric pressure pushes down on the material while the vacuum pump removes air from beneath it, creating a pressure difference that keeps the workpiece firmly in place.

How Strong is the Hold?
The force holding the material depends on the vacuum pressure and the surface area of the material. A larger material has more surface area in contact with the vacuum, increasing the holding force.

See the diagram below for a visual explanation of how vacuum tables generate hold-down force
See the diagram below for an illustration of cutting forces acting on the material

The CNC router we worked with has a vacuum table divided into six independent sections, controlled by valves. Each section can be activated or deactivated depending on the size and position of the material being cut. By closing certain valves and keeping only the necessary sections open, we could optimize the suction force applied to the board, making sure it stayed completely flat against the sacrificial board.

• Material surface area Larger pieces experience stronger suction.
• Leaks or gaps in material Air leaks reduce the vacuum’s effectiveness, so materials with holes or rough surfaces may need additional sealing
• Vacuum pump power A higher-pressure vacuum pump creates a stronger hold.

Sacrificial Board

The Role of the Sacrificial Board A sacrificial board is a layer of material placed between the CNC machine’s bed and the workpiece. Its main purpose is to protect the CNC table from tool damage while also improving vacuum performance.

• Protecting the CNC Table: Since CNC operations often involve cutting all the way through the material, the bit can cut slightly into the machine’s surface. A sacrificial board absorbs these cuts, preventing permanent damage to the actual bed.
• Enhancing Vacuum Hold Some materials, like plywood, have tiny air gaps that weaken the vacuum suction. A sacrificial board—typically MDF—creates a better seal between the vacuum table and the material, preventing air leaks and ensuring a stronger hold.
• Allowing Full-Depth Cuts Without Worry With a sacrificial board in place, users can confidently set their toolpaths to cut slightly beyond the actual material thickness, ensuring clean cuts without worrying about damaging the machine

Actions prior to cutting

Decide on the the type of cutting needed and change the bit for one that is appropriate. For this, the case that holds the collet will need to be loosened with a couple of wrenches. Depending on the width of the shaft of the bit a different collet could be needed.

First snap the collet into the collet nut and then insert the bit. The shaft of the bit should not stick beyond the collet it should stay 3mm away from the end of the collet in case the bit is long otherwise it will not clamp well. Also, make sure that the flutes are not inside the collet.

source: cutting it close

Thereafter inspect the board to check that the board is even and flat. Otherwise correct for this with clamps or screws.

It is important to make sure that when setting the cutting area to take into account for this, in order to avoid that the milling over this metal pieces as it is very dangerous!

It is a good idea to test the table vacuum in order to see if the wood will move by pulling sideways.

Use the controller xy + and - buttons to re position the CNC head to the start point or origin. Remember that x increases from left to right, z from bottom to top and y increases from the control station to the back of the room. In order to set up the z origin it is necessary to take small steps to touch the board lightly with the bit. In order to do this it is a good idea to activate the table vacuum as this will change the z position of the board.

Files

• Download Computer-controlled machining- Lab Safety Training

• Download Feed Rate Calculator
• Download test files - Runout + Speeds and Feeds

Group Task Distribution

ComMarker B4 MOPA 60

Specifications:

• Laser Source: MOPA-JPT
• Laser Power: 60W
• Laser Wavelength: 1064nm
• Engraving Accuracy: 0.01mm
• Engraving Speed: 0-15,000 mm/s
• Frequency 1-4000 KHz
• Pulse Width: 2-500ns
• Work Area: 110mm x 200mm dual lenses
• Primarily designed for engraving metals and plastics
• Can cut Stainless Steel, Aluminum, Brass, Copper, Silver and Gold.

In this page you can find a blog that describes the advantages that a fiber laser engraver have for PCB engraving. Below you cand find a short summary of this article.

The high precision laser technology of a fiber laser engraver allows to etch, cut and mark the different layers of a printed circuit board. Some specific advantages are:

• High Precision and Accuracy to achieve fine detail.
• Efficiency and Speed resulting in faster processing than traditional methods thanks to high speed galvo technology.
• Versatility: that allows processing several types materials.
• Auto Focus Technology: Allows adjustments based on material thickness and variations in the material surface.

This is a laser cutter that uses the MOPA technology i.e Master Oscillator Power Amplifier. This technology has a much wider frequency range than q-switch machines and it can also control the pulse width parameter enabling the control of the individual laser pulses.

In the fields of Electronics, Semiconductors, and ITO Precision Machining achieving precise lining is often essential. However, a Q-switched fiber laser struggles with this task due to its fixed pulse width. In contrast, a MOPA fiber laser, with its adjustable pulse width and frequency, effectively delivers smooth edges and precise results. Mopa Fiber laser has a tunable wdith which facilitates small laser spot and tunable energy (source: link)

Steps for engraving a PCB:

• 1. Design Circuit Diagram
• 2. Input the Circuit Diagram into EZCAD in our case we have a version of Lightburn.
• 3. Set Parameters power, speed, and frequency
• 4. Preview and adjust position and size
• 5. Initiate the laser engraving process.
• 6. Check the result.

Safety

These are some complementary safety guidelines to the ones that were described in week 3 as this is very powerful and potentially dangerous machine from the manual:

This is a powerful and potentially dangerous machine. We use an emergency stop button, which is important to quickly shut down the system in case of any issue.
The machine is also operated inside a protective case, which helps contain laser reflections and ensures safer use.
You can see the setup in the image below, where both the safety enclosure and the emergency stop button are highlighted.
Here is the enclosure we currently use for the fiber laser:
ComMarker Fiber Laser Safety Enclosure

• Laser Safety
  • The machines use Class Ⅳ lasers. The lasers are very powerful and can cause eye injuries and burnt kin. It is recommended to wear laser goggles when using the laser engraver.
  • Avoid exposing your skin to Class IV laser beams, especially at close range.
  • Do not touch the laser engraving beam while it is switched on.
• Material Safety
  • Do not engrave materials with unknown properties.
• User Safety
  • Use this laser engraving device only in accordance with all applicable local and national laws and regulations.
  • Use this device only in accordance with this instruction manual and engraving software manual.
  • DO NOT leave this device unattended during operation.
  • Cut off all power to the machine and contact either our customer service or repair service if anything seems to be working abnormally
  • Any untrained personnel who might be near the device must be informed the danger of the machine before operation

Some of this are scary that they need to put them.

---

PCB Milling and Laser Engraving: Workflow and Results

For our PCB fabrication process, we used a CNC milling machine to remove copper and create circuit traces. This involved several key steps, from preparing the files to sending them to the milling machine. Additionally, we explored laser engraving as an alternative method. Below is a breakdown of our process.

Preparing the File
To generate the milling paths, we used mods project, an online tool that allows customization for different bit sizes and milling parameters. For this we use the test file that they shared in the global class.

• Loading the File: We imported the test PNG file into Mods. This file contained small trace patterns to evaluate how well different bit sizes could mill fine details.

• Configuring Milling Parameters: In PCB Default Settings, we adjusted the trace width and tool diameter to match our selected bits. Using the Bit Calculator, we determined the cut depth and offset for each milling pass. In the Mill Raster 2D module, we configured the feed rate, cut depth, and number of offsets to define how much copper should be removed.
• Generating the Toolpath: Mods processed the data and provided a preview of the offset path, showing how many passes would be made around each trace.



• Exporting the G-Code: Once satisfied with the settings, we exported the G-code file to be used in Candle, the CNC control software.

When setting up the exterior cut in Mods, we explored the use of tabs, small uncut sections that keep the PCB attached to the base material during milling. This prevents the board from shifting or coming loose, ensuring a clean and precise cut while making it easier to remove afterward.

Sending the File to the CNC: Candle Software

With the G-code file ready, the next step was to send it to the milling machine using Candle, a G-code sender software, to control the CNC. The first step was to connect the machine and set the origin point for the milling process. This involved manually adjusting the bit’s height and using the jog controls in Candle to position the tool at the correct starting location.

In the image, we tested three different milling bit sizes:
The 0.1mm bit, located at the bottom , provided the sharpest detail, making it ideal for intricate traces and high-density PCB designs. However, due to its thin structure, it is also the most fragile and prone to breakage if not handled carefully. The 0.2mm bit, in the middle, offered a good balance between precision and durability, making it suitable for general PCB engraving while still maintaining fine details. The 0.4mm bit, at the top, was the most robust but resulted in wider traces, which may not be ideal for compact circuits but is useful for faster milling and larger traces. This test helped us determine the appropriate bit size based on the required level of detail and durability considerations for milling PCBs effectively.

Exploring: PCB Laser Engraving

For this test, we used a ComMarker B4 60W MOPA Fiber Laser to engrave a PCB instead of milling. We opted for engraving only since laser cutting the board leaves undesirable burns and discoloration. The goal was to test how different power settings and number of passes affected the engraving quality and depth.

• Preparing the File:We converted the PCB design into an SVG file for compatibility with the laser software. This with Inkscape using the option trace.
• Laser Parameters: Engraving Speed to adjusted to prevent overburning. The number of passes, we tested multi-pass engraving to determine the ideal depth. As well the engraving direction, the machine performed horizontal and vertical passes for even copper removal.

Top sample (2 passes, 90% power): Produced a dark, well-defined engraving, with strong contrast against the copper surface. However, the material removal was limited, leaving a slight texture.
Middle sample (4 passes, 90% power): Increased the engraving depth while keeping clear and legible details. The copper was effectively removed, revealing a more uniform and matte finish.
Bottom sample (6 passes, 30% power): Despite more passes, the lower power setting removed less copper, resulting in a subtle and less contrasting engraving. The details are still visible but not as deep or pronounced as the 90% power tests.

For the laser parameters we chose: Speed of 1500 mm/sec, a Maximum Power 90%, a Pulse width of 250ns, and a frequency of 30Khz

Key Learnings

This week’s exploration of PCB manufacturing techniques gave a better understanding of the trade-offs between milling and laser engraving. The milling tests showed how bit size affects precision, and the importance of settings like depth, feed rate, and toolpath optimization. Using Mods for file preparation allowed us to refine the process for different bit sizes, ensuring better control over the cut. The height map calibration in Candle also proved essential for maintaining accuracy, especially when switching between tools.

Group Task Distribution

For this week’s Input Devices assignment, we explored both analog and digital input signals through simulation and real-world testing. We began by simulating a potentiometer in Tinkercad.

Analog Input - Accelerometer / Potentiometer

To explore input devices, we worked with both analog and digital sensors using simulation tools and real hardware. I started with an analog input test using Tinkercad, where I connected a potentiometer to an Arduino UNO. In the simulation, the potentiometer was wired with one side to 5V, the other to GND, and the center pin connected to analog input A0. I used a simple Arduino sketch to read and display the analog values via the Serial Monitor, which helped visualize the range of values as I turned the knob. The code used for this simulation is shown below:

int sensorValue = 0;

void setup()
{
  pinMode(A0, INPUT);
  Serial.begin(9600);
}

void loop()
{
  sensorValue = analogRead(A0);
  Serial.println(sensorValue);
  delay(10);
}

This program prints the analog signal from the potentiometer every 10 milliseconds, allowing me to see a smooth transition of values on the Serial Plotter. It helped me understand how analog signals behave and how sensors can reflect continuous variation based on physical input. You can view and interact with the simulation here by opening the shared project.
Later, I recreated this analog test physically by connecting a real potentiometer to an Arduino UNO, then used a multimeter and an oscilloscope to observe the voltage changes on the analog output pin.

For the multimeter test, I didn’t need to connect the Arduino to read values. Instead, I connected one outer leg of the potentiometer to GND, the other outer leg to 5V, and then placed the positive (red) probe of the multimeter on the middle pin of the potentiometer (the wiper), and the negative (black) probe on GND. As I turned the knob, I observed a smooth change in voltage from 0V up to nearly 5V, confirming how the potentiometer acts as a voltage divider. This method provided a quick and direct way to verify that the component was working correctly without involving any programming or microcontroller.

Next, I tested the same potentiometer using an oscilloscope. Similar to the multimeter, I connected one probe tip to the center pin (wiper) and the ground clip to GND. The oscilloscope allowed me to see a real-time waveform that changed dynamically as I rotated the knob. This gave me a visual representation of how the voltage responded over time

Although both tools measured the same voltage range, the multimeter showed stable, precise values, while the oscilloscope provided a detailed, time-based view of the signal. These two tools together gave me a deeper understanding of how analog signals behave and how input devices like potentiometers can be tested from both static and dynamic perspectives.

Digital input - button

To explore digital input behavior, I created a simple simulation in Tinkercad using an Arduino Uno and a push button connected to digital pin 2. In the circuit, I connected one side of the button to 5V, and the other side to digital pin 2, with a 10kΩ pull-down resistor connected from pin 2 to GND. This resistor ensures that the signal reads LOW (0) when the button is not pressed, avoiding floating values. I uploaded the following code to read the state of the button

int buttonState = 0;

void setup()
{
  pinMode(2, INPUT);
  Serial.begin(9600);
}

void loop()
{
  buttonState = digitalRead(2);
  Serial.println(buttonState);
}

Once the simulation was running, I opened the Serial Monitor and observed the output values. When the button was not pressed, the serial output printed 0, and when I pressed the button, it changed to 1. This binary behavior clearly demonstrates the concept of digital input: it only has two states — HIGH and LOW. This activity helped reinforce how buttons can be used as inputs to trigger events or control behavior in physical computing projects.
You can view and interact with the simulation here by opening the shared project.

Group Task Distribution

For this week’s assignment, we measured a LED and a DC motor. We used a power supply station where the voltage can be set to a specific value and the amperage can be limited to a maximum. This power supply displays the current being used as well as the total power consumption in watts.

Before proceeding, we define power as:

P=IxV

where is current (in amperes) and is voltage (in volts). Power is typically measured in watts and can be estimated as a function of time, e.g., watt-hours.

Group Task Distribution

Arduino Serial Communication (RT/TX)

For the group assignment, we explored the basics of serial communication using several Arduino Uno boards. The goal was to simulate a basic network where one Arduino acts as the transmitter and the others act as receivers. We used Serial communication (RT/TX) and tested this through the Arduino IDE and a breadboard setup. We first connected two receivers and then added a third one to test multiple nodes reacting independently to a single transmitter.

Wiring and Connections

We used the following color-coded jumper wires to make our setup easy to understand and debug:

• Red: RX (Receiver)
• Blue: TX (Transmitter)
• Black: GND (Ground)
• Yellow: 3.3V Power

All the Arduinos shared the same ground (GND) and were connected via the TX pin of the transmitter to the RX pins of the receivers through a breadboard.

Code – Master (Transmitter)

void setup() {
  Serial.begin(9600);
}

void loop() {
  Serial.write('a');
  delay(100);
  Serial.write('b');
  delay(100);
  Serial.write('c');
  delay(100);
}

The transmitter sends a sequence of characters via Serial.write():
Each character corresponds to a specific node that listens for it. The delay(100) helps give time between messages so that each receiver can read and respond without conflict.

Code – Receiver (Node)

void setup() {
	Serial.begin(9600);
	pinMode(13, OUTPUT);
}
	  
	void loop() {
	if (Serial.read() == nodo) {
		digitalWrite(13, HIGH);
		delay(50);
		Serial.println("in loop");
	} else {
		digitalWrite(13, LOW);
	}
}

Each receiver is programmed to listen for a specific letter. When the correct letter is received, it turns on the built-in LED:
The variable nodo defines the unique address of each node. By changing this letter, each receiver only responds to its assigned message.

What We Observed

When we ran the code, each receiver board successfully detected its assigned character and responded by turning on its LED. For example, the board listening for 'a' only activated its LED when that specific character was sent by the transmitter.
The LEDs would flash in a pattern based on the order and delay of the characters being transmitted, giving us visible confirmation that the communication was working correctly.
Our basic multi-node serial communication system was functioning as intended!!

Adding a third receiver was quite straightforward, showing how this method can scale easily. This experience gave us a better understanding of how microcontrollers can communicate with each other in a simple but structured network.

Group Task Distribution

Text

This is bold and this is strong. This is italic and this is emphasized. This is ^superscript text and this is _subscript text. This is underlined and this is code: for (;;) { ... }. Finally, this is a link.

List Unordered

• Dolor pulvinar etiam.
• Sagittis lorem eleifend.
• Felis feugiat dolore viverra.
• Dolor pulvinar etiam.

Buttons

• Primary
• Default

• Large
• Default
• Small

• Fit
• Fit

Preformatted

i = 0;

while (!deck.isInOrder()) {
print 'Iteration ' + i;
deck.shuffle();
i++;
}

print 'It took ' + i + ' iterations to sort the deck.';

Group Task Distribution

Text

This is bold and this is strong. This is italic and this is emphasized. This is ^superscript text and this is _subscript text. This is underlined and this is code: for (;;) { ... }. Finally, this is a link.

List Unordered

• Dolor pulvinar etiam.
• Sagittis lorem eleifend.
• Felis feugiat dolore viverra.
• Dolor pulvinar etiam.

Buttons

• Primary
• Default

• Large
• Default
• Small

• Fit
• Fit

Preformatted

i = 0;

while (!deck.isInOrder()) {
print 'Iteration ' + i;
deck.shuffle();
i++;
}

print 'It took ' + i + ' iterations to sort the deck.';

Group Task Distribution

Text

This is bold and this is strong. This is italic and this is emphasized. This is ^superscript text and this is _subscript text. This is underlined and this is code: for (;;) { ... }. Finally, this is a link.

List Unordered

• Dolor pulvinar etiam.
• Sagittis lorem eleifend.
• Felis feugiat dolore viverra.
• Dolor pulvinar etiam.

Buttons

• Primary
• Default

• Large
• Default
• Small

• Fit
• Fit

Preformatted

i = 0;

while (!deck.isInOrder()) {
print 'Iteration ' + i;
deck.shuffle();
i++;
}

print 'It took ' + i + ' iterations to sort the deck.';

Group Task Distribution

Text

This is bold and this is strong. This is italic and this is emphasized. This is ^superscript text and this is _subscript text. This is underlined and this is code: for (;;) { ... }. Finally, this is a link.

List Unordered

• Dolor pulvinar etiam.
• Sagittis lorem eleifend.
• Felis feugiat dolore viverra.
• Dolor pulvinar etiam.

Buttons

• Primary
• Default

• Large
• Default
• Small

• Fit
• Fit

Preformatted

i = 0;

while (!deck.isInOrder()) {
print 'Iteration ' + i;
deck.shuffle();
i++;
}

print 'It took ' + i + ' iterations to sort the deck.';