Dry Etch

Fenadora International Pizza Scale

noreply@blogger.com (Hugo Santos) — Sun, 19 Apr 2026 06:54:00 +0000

I think we can all agree that modern engineering is powered by two fundamental elements: a) coffee and b) pizza.

On a family trip to Italy, we came across a difficult question: "How do you compare and evaluate pizza?"

To answer it, we came up with a brilliant solution: the Fenadora International Pizza Scale.

La Fenadora

La Fenadora is a pizzeria in the province of Belluno, Italy. Established in 1997, it serves fantastic wood-fired pizza.

As soon as you arrive at the car park, you're surrounded by mountains, and you immediately get the feeling that you are in a special place.

Therefore, the perfect name for our pizza scale.

How It Works

The scale is simple.

A pizza from La Fenadora sets the baseline. All other pizzas are compared against it using an integer scale from 0 to 10.

Evaluation Criteria

So, what do we look for?

Is the pizza properly cooked? (burnt or undercooked?)
Is it tasty?
Would you come back for it anytime soon?

Based on these highly scientific criteria, assign a score from 0 to 10.

... And that's it.

Self Balancing Robot

noreply@blogger.com (Hugo Santos) — Sun, 31 May 2015 12:54:00 +0000

Since I know the digital gyroscope I have a particular interest by this component, due the fact of being used in a lot of modern systems, like smartphones or aircraft industries.

To participate on Lisbon Maker Faire I built a project that used this amazing component, called Self Balancing Robot [SBR].

The SBR helps to understand the principles behind the Segway vehicles. The robot stands in two wheels using the gyroscope inclination readings to position the mass center of the robot in vertical.

Bill of Materials

1-Arduino Nano V3.0 ATmega328P 5V Board
2-MPU-6050 3 Axis Accelerometer Gyroscope Module
3-DC Gear Motor With Wheel
4-Battery Rhino 610mAh 2S 7.4v 20C Lipoly Pack
5-Battery Charger HobbyKing™ E4 Balance Charger
6-Motor Driver L293D - Quadruple Half-H Driver
7-PCB 33x70 mm Single Side Copper + Silkscreen by: eLab
8-Acrylic 100x90x4,74
9-Screws/Bolts/Metals

L293D - QUADRUPLE HALF-H DRIVERS

The L293D is designed to provide bidirectional drive current of up to 600mA (1.2A peak) at voltages from 4.5V to 36V. Its designed to drive inductive loads such as relays, solenoids, dc and bipolar stepping motors, as well as other high-current/high-voltage loads in positive-supply applications.

All inputs are TTL compatible. Each output is a complete totem-pole drive circuit, with a Darlington

transistor sink and a pseudo-Darlington source.

Drivers are enabled in pairs, with drivers 1 and 2 enabled by 1,2EN and drivers 3 and 4 enabled by 3,4EN. When an enable input is high, the associated drivers are enabled, and their outputs are active and in phase with their inputs. When the enable input is low, those drivers are disabled, and their outputs are off and in the high-impedance state. The next image shows the block diagram.

Battery Rhino 610mAh 2S 7.4v 20C Lipoly Pack

Purchased on HobbyKing.com, this 7.4V battery can provide 610mAh (capacity) and contains two cells of 3.7V each connected in series (2S). The discharge rate (20C) means this battery can discharge safely 20 times more than the capacity of the pack.

So far the autonomy was between 3 to 4 hours and the charge took 30 to 50 minutes.

Gyroscope + Accelerometer MPU6050

The MPU-6050 is an integrated 6-axis MotionTracking device that combines a 3-axis gyroscope, 3-axis accelerometer, and a Digital Motion Processor™ (DMP). It features three 16-bit analog-to-digital converters (ADCs) for digitizing the gyroscope outputs and three 16-bit ADCs for digitizing the accelerometer outputs.

The triple-axis MEMS gyroscope in the MPU-6050 includes Digital-output X, Y, and Z Axis angular rate sensors (gyroscopes) with a user-programmable full-scale range of ±250, ±500, ±1000, and ±2000°/sec and the triple-axis MEMS accelerometer includes Digital-output triple-axis accelerometer with a programmable full scale range of ±2g, ±4g, ±8g and ±16g.

Communication with all registers of the device is performed using I2C at 400kHz. I2C is a two-wire interface comprised by the signals serial data (SDA) and serial clock (SCL). In general, the lines are open-drain and bi-directional. In a generalized I2C interface implementation, attached devices can be a master or a slave, the master device puts the slave address on the bus, and the slave device with the matching address acknowledges the master. The MPU-6050 always operates as a slave device when communicating to the system processor, which thus acts as the master.

The slave address of the MPU-6050 is b110100X which is 7 bits long. The LSB bit of the 7 bit address is determined by the logic level on pin AD0. This allows two MPU-6050s to be connected to the same I2C bus.

Additional features include an embedded temperature sensor and an on-chip oscillator with ±1% variation over the operating temperature range.

The MPU-6050 is built using three independent vibratory gyroscope MEMS , which detect rotation in the X, Y, and Z Axis. When the gyros are rotated about any of the sense axis, the Coriolis Effect causes a vibration that is detected by a capacitive pickoff. The resulting signal is amplified, demodulated, and filtered to produce a voltage that is proportional to the angular rate. This voltage is digitized using individual on-chip 16-bit Analog-to-Digital Converter (ADCs) to sample each axis.

The accelerometer uses separate proof masses for each axis. Acceleration along a particular axis induces displacement on the corresponding proof mass, and capacitive sensors detect the displacement differentially. The MPU-6050 architecture reduces the accelerometer susceptibility to fabrication variations as well as to thermal drift. When the device is placed on a flat surface, it will measure 0g on the X and Y axis and +1g on the Z-axis. The accelerometer scale factor is calibrated at the factory and is nominally independent of supply voltage. Each sensor has a dedicated sigma-delta ADC for providing digital outputs. The full scale range of the digital output can be adjusted to ±2g, ±4g, ±8g, or ±16g.

Printed Circuit Board and Schematics

The printed circuit board was made in KiCad version 2013-07-07 BZR 4022 Stable. Some components were custom made and some from specific libraries including the 3D models. The next image shows the schematic.

On the next images is shown the Printed Circuit Board and its 3D model ready to print and start the fabrication.

The next image shows some steps to fabricate the PCB. In general steps it was used the toner method and etching with muriatic acid and hydrogen peroxide.

The next image shows the components in place and the PCB mounted on the acrylic.

Algorithm

The Arduino Nano receives the gyroscope readings by I2C. Due the noise introduced into the circuit by motors, the readings floated a lot. To compensate this fact it was used a Kalman filter, to filter those nasty peak readings keeping values in a steady level.

The gyro offset was adjusted to 0 degrees on robot mass center. The gyro took readings on y axis tilt. Between 18 to -15 degrees it was defined the main operation area for the robot and in this area the microcontroller will send 5ms pulses to the wheels, and if the structure was perfectly aligned in 0 degrees the wheels totally stopped.

The second defined operation area was defined to 50 degrees, with 10ms pulses to the wheels. These stronger pulses permitted to align the mass center faster, to don’t let the block misalign to a danger area, never recover and fall to the floor.

The third defined region was a safety feature. When the robot is horizontally aligned the wheels are disconnected to guarantee that the robot do not run away. The code is available in my Github.

Final

The SBR was ready to the Lisbon Maker Faire. The feedback of the visitors was positive and I also received improvement suggestions like Bluetooth control with a mobile app. It was a fantastic opportunity to build something and see people's reaction in first place!

The next photos and videos show the final results :)

Special thanks to the eLab team for the motivation and final adjustments :)

Codebits 2014

noreply@blogger.com (Hugo Santos) — Fri, 02 Jan 2015 15:34:00 +0000

Since long time ago i dreamed about participate on Codebits, a programming event that puts together computer programmers and enthusiasts, during 3 days in Meo Arena, Lisbon (10-12 April).

The access for this event is exclusive and from thousands of candidates only 800 were selected and i was one of them. The best part is some friends applied being selected to.

The format of the event is amazing, because it encourages the direct contact between programmers and also with all workshop speakers, some of them working in very iconic places like Christian Heilmann from Firefox or Tor Björn Minde from Ericsson.

The workshops contents were vast starting by web development, to telecom, embedded systems, electronics, algorithms, human interfaces, 3d printing, product developments by enterprises, and so on.

Because we put together a good team we applied to build a project in 48 hour competition. [Missing Luís Carlos on the photo]

The project was called - Game of Drones. Quoting our registration pitch: " Game of Drones will bring an amazing augmented reality experience as never seen before! This will be a multi-player game using low-cost quadcopters and computer vision technology. Players will be able to play an impressive death-match battle against each others. The drones are coming ... only the strongest will survive !!! "

The game philosophy is aim & shoot multiplayer death match and the player controls the quadcopter, by computer. The augmented reality interface shows real time image with the aim and score.

The quadcopter integrates a small usb webcam connected to a TP-Link WR703N Wi-Fi router, running Linux OpenWrt OS, to stream the video to the computer.

The computer is running a Python application, to receive the video streaming and apply a computer vision algorithm, to track the opponents and add visual effects.
The quadcopter control is made by a mechanical overengineering, tha actuates over the original RF remote control, using a arduino uno and a servo motor, keeping the remote untouched.

We split in two teams, one working on quadcopter control and another working on communications and augmented reality interface.
Me and my team we start working and we name it - Control Inception. The first challenge was construction of console to accommodate the RF control and something capable so move the joysticks with 360 degrees of freedom.
We became with the firs prototype, with two PVC arms, small bearings and a bracket made of Polystyrene, for servo motors.

Check the movements in this video.

After test this small structure with success, we used transparent acrylic for the final console. Starting by a big sheet, we cut and finish by hand the forms of frontal panel.

After cutting all holes we put servos in place and the result is the follow.

The next step was cutting the mini arms, make the holes for bearings, connect the to servos, and let ready the holes for remote. Because we had free clouds of cotton candy, we used the as stress test to see if all the controls were precise.

Check the prototype in action.

After all things tested, we connected all pieces, and the result was this:

Project finished it was time to hurry up and submit the presentation video to jury :)

Node School

noreply@blogger.com (Hugo Santos) — Fri, 14 Nov 2014 00:02:00 +0000

At 2 of August me and my colleges went to a fantastic node.js event called Node School, co-organized by Nelson Neves, during a Geek Session at Faro Co-Working Space.

The event had 13 node.js challenges and the code was submitted and verified by a platform called learnyounode.

To make this workshop, it was needed to install node.js, npm and learnyounode:

$ sudo apt-get install nodejs

$ sudo apt-get install npm

To run node.js recent versions in command line, instead of: $ node <program_name> the command is $ nodejs <program_name> .

To fix this it was needed to create a symbolic link:

$ sudo ln -s /usr/bin/nodejs /usr/bin/node

After this initial steps, just run:

$ learnyounode

To verify the code of each exercise:

$ learnyounode verify <program_name.js>

After all exercises completed we received a: Much Win.

Check all solutions on my GitHub repository.

Lisbon Mini Maker Faire

noreply@blogger.com (Hugo Santos) — Sun, 09 Nov 2014 23:12:00 +0000

During the days of 19, 20 and 21 of September me and my colleagues from eLab Hackerspace, had the amazing opportunity to participate on the first Maker Faire in Portugal.

The event hosted 100 maker projects and 10.000 visitors on "Pavilhão do Conhecimento". Organized by Make magazine, Sapo another tech partners, we submited our projects to the ultimate stress test - The People's Judgement! It was interesting receive feedback from the public about our projects, in major part very good comments and also improvement suggestions, in some cases possible deal offers.

The climate between makers was awesome and it was nice environment to learn new things, some of them cutting edge technologies and some of our projects were awarded.

In the event me and my great friend João Duarte presented a workshop about Kicad - Printed Circuit Design Software, where we explained and demonstrate in exactly 1 hour, the steps to design a simple PCB in Kicad.

Let's check some of eLab's projects.

This is my personal project called Self Balancing Robot and equilibrates in two wheels with the help of an accelerometer + gyroscope by the same principles of a segway [Cover in another post].

The next project build by João Duarte is the awarded and sensation project from the Maker Faire - Tesla Coil.

Impressive by noise and sparks, its impossible not stop and look for this master piece, made with a corona beer capacitor, cooper wires and tubes, and high voltage transformer.

The next friend, Mário Saleiro was awarded by the number of projects taken to the Maker Faire. Mario was the first true maker in my EE course showing everybody how to break the boundary between theory and real creations. One project build by Mario and Bruna Carmo is Infantes and is a revolutionary approach for teaching children about programming and general knowledge games.

As a maker, Mário built his own CNC milling machine and the construction details are fantastic.

This is Miro a computer vision investigation bot.

Here we can see this custom made mechanical keyboard, with usb ports and internal memory.

This project made by top Engineer Nelson Neves present us a home automation feature - Intel Window. This window is controlled by a intuitive web interface controls a servo motor with gears brackets and box printed in 3D tech.

The next project made by Gonçalo Pereira, finished and presented by Álvaro is - The Spot Welder.

Made with a microwave transformer, this project welds together 2 pieces of metal as we can see in the next image.

The next project built by the RF expert Emído is - The Optical Communicator, and modulates and transmits data by led.

To finish here is a photo of eLab Hackerspace team at the Faire.

Test 101

noreply@blogger.com (Hugo Santos) — Sun, 02 Nov 2014 17:58:00 +0000

Hi there,

This is the Hello World of the Dry Etch blog. Dry Etch will be my personal micro-blog and will show some of my works as a Maker and Electronics student.

Why the name Dry Etch?

Dry Etch or more precisely Dry Etching, is one of the most widely used processes in semiconductor manufacturing. Dry etching uses plasma generated free radicals to remove material only from the area dictated by a photoresist pattern created during the photolithography step.

The following image shows an etched silicon template for micro gears.

This blog will support me by providing a faster way to find documentation about my works and help another makers like me.