header
// 1-Principles and proyect management   // 2-Computer-aided design // 3-computer-controlled cutting
// 4-electronics production // 5-3D scanning and printing // 6-electronics design // 7-molding and casting
// 8-embedded programming // 9-computer-controlled machining // 10-input devices // 11-composites  
// 12-interface & application programming // 13-output devices // 14-networking & communications
// 15-mechanical design, machine design // 16-appplications and implications
// 17-invention, intellectual property and income // 18-project development
// FinalProject // 


Week4: Electronics Production

This week we learn the the different ways and materials to make a PCB with components inside. At the end of the week we must build the FabISP.

Working with the Modela


The first thing we must do is to cut in a rigid PCB, with the Modela, the diagram of the FabISP circuit. I choose the Hello.ISP.44.cad board, because seems to be easier for my first PCB.

I downloaded the traces file and the interior file from the Fab Academy web page.

Download traces of Hello.ISP.44

Download interior of Hello.ISP.44

This was my first time working with the Modela, and it seems to be a machine with a lot of precision. Here in the Fab Lab Leon we had a great workflow to work with the modela. The 1/64 endmill seems a really small thing. First thing I need to do is practice with placing the Z axis in the correct position. ¿Why this machine doesnt have a Z-cero caliber, as the CNC? The way i must put the enmill touching the PCB is highly stressful ! :)

After some testing finally started to mill the PCB with the circuit. This was the parameters in fab modules.

Parameters with modela

The PCB seems not well attached to the base, so in half of the PCB the mill do his job, but at the other half dont mill enough. To correct this i made other pass , adjusting the Z a little bit down, as you can see in the parameters. The first pass was with 2Dz at -0,1mm and the second pass was with 2Dz at -0,15mm.

This seems to be enough to make a nice cut with the 1/64 endmill.

using the Modela

Finally I cut the margin with the 1/32 endmill with the following parameters:

interior cut






Assembly components


Now we must fill the PCB with the components required. This is the list and the diagram:

RESISTANCES: R1 1K // R2 499 // R3 100 // R4 100 // R5 10k

CAPACITORS: C1 1uF // C2 10pF // C3 10pF

DIODERS:  D1 3,3v // D2 3,3v

An ATTINY 44 microcontroller

A 20Mhz Cristal

Mini USB conector

J1 ISP connector

DIAGRAM: CLICK HERE


Then i solder the components on the PCB as seen on the diagram. Thanks to Ruben Ferrero that teach me the basis of soldering with tin, my first time soldering wasnt a nightmare. First i must heat the pad, then put a little cuantity of tin, and then heat the pin of the component and the pad at the same time. Finally we add a bit mor tin to cover the pin.

all components solder

After some practice, i get all the resistances, capacitors, dioders and the ATTINY44 micro solder to the PCB. Then i must put the 0 resistances in their position. A teammate in the fab lab, Alejandro, suggest me to put a pair of jumpers in the 0 resistances position. So if  in the future if i need to reprogram the PCB, i just need to put the jumper. If the software is ok ,i must remove the jumpers to avoid it to delete the firmware.

So here are my tho jumpers in the PCB:

jumpers in the pcb



Yes, i know, i must improve my skills in soldering :)

Finally we add the J2 and J1 connectors and the Mini USB.


pcb finish

After this, the multimeter says that some pins of the Mini USB arent well solder. So i spend a hole morning trying to solve it. After check that all the paths goes individually, i can finally program de FabISP.


Programming the FabISP

To program it we use another valid FabISP in Fab Lab Leon. Connect the two USB of the two PCB to a MAC computer, and then make a 6 pin cable to attach at the J1 connector. Be sure the red cable are at the same position in both PCB.

After this, make all the process:


nano Makefile (here we change the option to use MiniUSB 

make clean

make hex

(sudo) make fuse (check programmer in Makefile, may need to repeat)

(sudo) make program
Everything goes fine, and all the process completed with an OK. Then un plug the PCB and try that a Windows computer recognice it as a FabISP....without luck.


After spending couple of hours inspection it and re-do all the process, my instructor Nuria Robles realized that the V pin of the MiniUSB got out of the housing, and that was the problem.

So i must start all the process again, to get a shiny new FabISP Programmer.


! electronic are really hard job !


UPDATE: finally i review all the pcb and find some traces that arent well connected, and at the end i could program the FabISP and it can program other boards....!great!

Starting with the Andy FABIsp


After realize that the mini USB connector is a nightmare to a new-born in soldering like me, i try the Andy FabISP, which has a built in USB connector in his copper layer. So no more small pads to solder the miniUSB... yahooo!!!

Here you can see the Andy FabISP: http://fab.cba.mit.edu/content/projects/fabispkey/index.html


I download the routes and the interior, milled in the Roland modela and solder the components on it. The schema isnt really self-explaining, because the ground are all around the programmer, so its hard to see clear which pads are for which component.

After guess the components i solder all the stuff in the pcb, and got a FabISP.

fabisp andy with some fix

Unfortunately this fabISP isnt working no more. My skill in solder wasnt good enogh for this programmer, and i finish burning the traces.

Later in time i try to fix this board, and finally got a FabISP with USB incorporated...nice and small.


If you cant build a FabISP and has an AVR programmer, you can use it to program the nex boards in the Fab Academy.
Installing the programmer AVR in Windows 7 64 bits:


Download WinAVR from here: http://sourceforge.net/projects/winavr/files/