WEEK 3 : Electronics Production Week

“Electronics is not for the Weak”

 

Electronics Production

 

This week we learn about designing, meticulously milling, soldering and later programming a circuit.

 

DAY 1

 

The first assignment was to make a FAB ISP. The FabISP is an in-system programmer for AVR microcontrollers, designed for production within a Fablab.

 

The design files are available for download in the Fab Academy page here(http://fabacademy.org/archives/2015/doc/electronics_production_FabISP.html)

 

We downloaded the following designs:

http://fab.cba.mit.edu/content/projects/fabisp/fabisp.png

http://fab.cba.mit.edu/content/projects/fabisp/fabispdim.png

 

 

 

NOTE : Always make sure the copper side of the board is not touched with the fingers, it might cause oxidization.

 

First place a copper board and stick it with double sided tape straight and strongly onto the milling board, this is the sacrificial layer. On top of this layer, stick the next layer that is to be milled.

 

After giving the command on Kokopelli (Traces) the circuit may be milled using the 1/32 cm size bit. Once milling is done, use the 1/62 cm bit to cut the circuit board out. Since the circuit board is stuck strongly due to the double-sided tape, it is good to use a thing strong object like steel measuring scale or a thin screwdriver. Then we moved on to my favorite part, soldering the circuit.

 

As a standard practice, Franc said while assembling the components before soldering, it is good to write the component name on a blank piece of paper, circle it and place the components on the respective circles.

 

Franc also explain when smart boys solder they:

·         Use eye loupes for better visibility

·         Have amazing lighting as if for a photo-shoot

·         Fixate the corner legs and then later the others

·         Hold the component still with one hand when soldering

 

 

 

NOTE :  Bubble free - And also, while placing the copper board, on has to make sure it is stuck with double sided tape properly onto the sacrificial layer. If there are any air bubbles on it, make sure it is pushed out or so, else the board would not be straight and milling will be distorted. This will cause in improper milling of the circuit and the bit might only scrape thru the top layer of the board.

 

Once the circuit is milled.

 

 

DAY 2

 

Franc started off the day us a basic walk thru about essential components and uses for anyone who intends to tinker with electronics. The following were discussed:

 

Switch

A switch responds to an external force to mechanically change an electric signal. Switches are used to turn electric circuits ON and OFF and to switch electric circuits. Basically what this means is that when you push down or flick a switch you are allowing current to flow through to the rest of the circuit.We have many different kinds of switches the most common are Toggle Switch, Push button Switch, Selector Switch

 

 

Diode

A diode is a specialized electronic component with two electrodes called the anode and the cathode. Most diodes are made with semiconductor materials such as silicon, germanium, or selenium. Some diodes are comprised of metal electrodes in a chamber evacuated or filled with a pure elemental gas at low pressure. Diodes can be used as rectifiers, signal limiters, voltage regulators, switches, signal modulators, signal mixers, signal demodulators, and oscillators.

Light Emitting Diode: The LED converts current into light. This type of diode is especially popular and is most commonly found in small electronics stop street lights and we may even see it finding its way into house lighting being cheaper and more Eco friendly.

 

Resistor

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. Resistors act to reduce current flow, and, at the same time, act to lower voltage levels within circuits.

 

Capacitor

A capacitor (originally known as a condenser) is a passive two-terminal electrical component used to store electrical energy temporarily in an electric field.

 

Transistor

A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit.

 

Potentiometer

A potentiometer, informally a pot, is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat.

 

Motors

An electric motor is an electrical machine that converts electrical energy into mechanical energy.

 

Microcontroller 

A microcontroller is a small computer (SoC) on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of Ferroelectric RAM, NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM

 

 

After this session, milling and soldering of FABISP was done.

 

 

 

DAY 3

 

Electronics design using Kokopelli

 

We learnt how to design our own circuits. Firstly we downloaded a standard circuit from the Fab Academy website and then further went on the modify it by varying and writing additional lines of code to further add 3 components:

 

·         LED

·          Resistor

·         Button switch

 

 

 

 

Modified Kokopelli Design -> Milled Board -> Final Board

 

Clean Up !!

Franc also asked me to clean up the Modela machine from all the wax milling that was being done. He also explained to us how we should collect, reuse and recycle the wax leftovers from milling the machinable wax. This machinable wax that was available here at the Fablab was dark blue in colour, and of a lower quality and might be prone to melting (while milling). In fact while melting and reusing the wax, to improve the quality, one can add HDPE, reusable polythene. HDPE is usually used in the plastic covers we get in stores.

 

Use fab modules to mill the board.

 

 

DAY 4

Embedded Programming

 

Today’s lesson is on Embedded programming. Embedded systems programming is the programming of an embedded system in some device using the permitted programming interfaces provided by that system. Embedded Java is an example of a development environment for programming embedded systems that will execute Java programs. Our tutor, Franc spoke to us about the different levels of programming languages : High level languages, Mid Level Languages (C, C++), Low level languages (Assembly language). C is the most commonly used language in programming and C also  remains a very popular language for micro-controller developers due to the code efficiency and reduced overhead and development time of the language. C offers low-level control and is considered more readable than assembly.

 

 

 

Programming Hello FTDI

 

We had already milled & soldered a Hello World board. Next step is to program the same. To program we require :

·         The Fab ISP

·         A mini USB cable

·         FTDI header cable &

·         Of course, our HELLO WORLD Circuit

Next step is to connect our laptop & the ISP using the mini USB cable and connect Hello World to our ISP(being wary of  the orientation). Next is to run Arduino as Root(sudo./arduino @ terminal), assuming the ATTiny libraries have already been adeed. Select Tools Menu Board->as ATTiny and Processor->ATTiny44 and Programmer->usbtinyisp.

 

Now to load the blink code to the board. All we need to do is set the LED pin as PIN 8 (since we have connected the LED there on the board and compile the program and upload : Voila : *blinks*

 

 

 

 

 

Serial communication (send something to computer, read something from computer)

 

In serial communication we use FTDI header to communicate with our Computer. The FTDI header have 6 Pins and the other end is USB with which we connect it to our Laptop.

 

Generally we use SoftwareSerial headers for serial communication. So we need to include the library in our program to enable serial communication. We wrote a program for turning on LED connected to pin 8 when we send character "c" from Laptop and send character "e" back when we press the button on the board.

 

 

Program code

 

Now connecting the board to FAB ISP and the FTDI header to the board and next connect the other end to Laptop. Burn the program to the board using ARDUINO. On completion, open the Serial monitor window and press the button in the board.

 

 

Serial monitor pic

 

 

 

DAY 5

Video Conferencing and Catching up