I don't quite remember how I came across Atmel AVR microntrollers. Pre AVR days consists of handyboard, then some PLC kits, then a Basic Stamp kit, a smudge of embedded Linux somewhere in between, and finally the AVR days arrived. The concept of automation was always in the back of my mind but all of above ventures ended up gathering dust somewhere. Running Linux made things a bit more challenging, often beyond my meager skills and my short 30 seconds.

This image pretty much shows my tortuous and slow progression through various AVR incarnations. I started with STK500, then the C Programming Book for Microcontroller base on the AVR Butterfly, then Sparkfun's tutorials using the ATMega16, then a one day affair with Arduino through The Public School's Practical Electro-Mechanical class. Finally, with reprap generation 3 motherboard powered by AVR, I am going through Sparkfun's tutorial again but this time kind using the less expensive ATTiny2313. It's the least expensive AVR microcontroller with the external oscillator capability. Looking back I wish I had discover AVR sooner. It seem to be the least expensive but most versatile option.

Hopefully all the puzzle pieces will converge one of these days. . . .

The laborious task of kitting together the Stepper Motor Driver V2.3 is done. Though I just discovered that Stepper Motor Drive V3.0 is in the works. It looks like the stepper motor driver IC will be changed from Allegro A3982 to A3977. I haven't progressed far enough in my microcontroller circuit building to understand the different but a quick search says something about A3977 gives a 25% increase in peak current. The cost for Stepper Motor Driver V2.3 is as follows.

Part Name	Qty	Vendor	Vendor Part No	Cost	Ext Cost
.156” 4 position housing	1	Mouser	538-09-50-3041	0.250	0.25
.156” crimp-on connector	4	Mouser	538-08-52-0072	0.080	0.32
.156 header	4	Mouser	538-26-48-1245	0.084	0.34
.22uF ceramic capacitor 1206	1	Digi-Key	339-1251-1-NDD	0.143	0.14
0.25 ohm resistor 2512	2	Digi-Key	CSRN20.25FICT-ND	0.608	1.22
10 pin IDC connector	2	Digi-Key	609-1839-ND	0.710	1.42
10 pin IDC header	1	Mouser	649-75869-101LF	1.030	1.03
100nF ceramic capacitor 1206	5	Mouser	80-C1206C104K5R	0.070	0.35
100uF electrolytic capacitor D55	2	Digi-Key	493-3209-1-ND	0.867	1.73
10k ohm resistor 1206	1	Mouser	290-10K-RC	0.050	0.05
10k trimpot	1	Mouser	72-T70YE-10K	0.740	0.74
1k ohm reistor 1206	4	Mouser	290-1.0K-RC	0.050	0.20
1nF ceramic capacitor 1206	1	Mouser	80-C1206C102K5R	0.090	0.09
2.2k ohm resistor 1206	1	Mouser	263-2.2K-RC	0.050	0.05
4 pin molex connector	1	Mouser	538-15-24-4745	0.840	0.84
7805DT	1	Mouser	863-MC7805CDTRKG	0.470	0.47
A9382	1	Digi-Key	620-1299-1-ND	5.810	5.81
Green LED 1206	1	Digi-Key	350-2053-1-ND	0.238	0.24
Red LED 1206	3	Mouser	645-598-8210-107F	0.100	0.30
RJ45 Jack	2	Mouser	571-5555164-1	0.740	1.48
Stepper Motor Drive V2.3 PCB	2	MakerBot	tv448	3.000	6.00
10 pin ribbon cable	1	Mouser	523-191-2801-110FT	0.470	0.47
				Subtotal:	23.54

Hackerspace documentation states:

"The rule of thumb is 2+2. You need a partner to get the initial idea kicked off, making two of you. You need two more people in order to get real work done. Don’t start before you are at least four people. From this point it’s easy to recruit more people. Aim for ten people for a start."

Anyone else interested in setting one up in the the Pasadena/Arcadia/El Monte area of Los Angeles, California, USA.

The hackerspace wiki space can be found here

Most of the parts for building the 3rd generation Reprap electronics have arrived and the cost of the mother board is listed below. Too bad Makerbot is out of stock on their motherboard kit because it took hours spanning several days to order, receive, sort, and group all the parts from three different vendors. . . . and this is just for the motherboard, I haven't even started kitting together the 3 stepper motor drive boards.

Part Name	Qty	Vendor	Vendor Part No	Cost	Ext Cost
.100 breakaway header	6	Mouser	571-9-146304-0	0.086	0.513
1.8K ohm resistor 1206	5	Mouser	263-1.8K-RC	0.050	0.250
10 pin female header	4	Digi-Key	S7008-ND	0.458	1.832
10 pin IDC header	4	Mouser	649-71600-010LF	0.800	3.200
100nf ceramic capacitor 1206	3	Mouser	80-C1206C104K5R	0.070	0.210
10K ohm resistor 1206	4	Mouser	290-10K-RC	0.050	0.200
10uF electrolytic capacitor D55	1	Mouser	647-UUT1H100MCL1GS	0.080	0.080
15pF ceramic capacitor 1206	2	Mouser	77-VJ12A100V150J	0.060	0.120
16Mhz crystal	1	Mouser	695-HC49US-16-U	0.580	0.580
180 ohm resistor 1206	1	Mouser	263-180-RC	0.050	0.050
1k ohm resistor 1206	2	Mouser	290-1.0K-RC	0.050	0.100
3.3k ohm resistor 1206	3	Mouser	263-3.3K-RC	0.050	0.150
30 ohm resistor 5W	1	Digi-Key	30W-5-ND	0.340	0.340
3M sd card socket	1	Mouser	57-SD-RSMT-2-MQ	1.300	1.300
4 pin female header	4	Digi-Key	S7037-ND	0.383	1.532
4.7k ohm resistor 1206	2	Mouser	263-4.7K-RC	0.050	0.100
6 pin IDC header	1	Mouser	649-75869-131LF	0.430	0.430
Atmega644P tqfp	1	Digi-Key	ATMEGA65P-20AU-ND	7.760	7.760
ATX Motherboard header	1	Mouser	538-39-29-3206	1.860	1.860
Green LED 1206	1	Digi-Key	350-2053-1-ND	0.238	0.238
Omron B3F-1000 Button	1	Mouser	653-B3F-1000	0.230	0.230
RED LED 1206	1	Mouser	645-598-8210-107F	0.100	0.100
RJ45 Jack	4	Mouser	571-5555164-1	0.740	2.960
SN75176A SOIC	1	Mouser	595-SN75176AD	0.880	0.880
SPDT switch	1	Mouser	10SP001	0.380	0.380
RepRap Motherboard V1.2 PCB	1	MakerBot	tv274	8.000	8.000
				Subtotal:	33.395

The GNU/Linux logo is a two color logo however the laser engraving is an monotone process. If a single power setting is used, the feet and mouth of the penguin will simple merge into one continuous blob. To achieve a gray tone effect, the laser power intensity can be adjusted as defined by the different color area of the logo. The logo is color separated into two separate colors. and different power settings are applied to each color. Also, because of the MDF substrate underneath the paper vaneer, the actual engraved surfaces are lighter in color. To enhance the logo detail a black color fill is applied to the engraved area after the engraving process. The finished product can be found on TheCuriousPenguin.com.

Taking the plunge head first into a shallow pool is the result of not reading through the reprap documentations more carefully.

I finally have the electronics portion of the extruder controller V2.2 assembled. . . I thought the initial reflow soldering was passable until I took some desoldering wicks to the SMT chips and took out almost half of the visible solders. Yicks!

Anyway so I have an assembled extruder controller V2.2 only to realize that the Arduino based reprap controller I was so fixated on is old gen2 technology. I've been itching to try out my Arduino board ever since I took the practical electro-mechanical class at ThePublicSchool. Unfortunately, the new gen3 electronics no longer uses Arduino as the main controller and instead uses Sanguino. Gen3 electronics is also "cleaner" looking with integrated power circuit from the main controller board to the peripheral boards such as as the extruder and stepper motor drive via RJ45 connectors.

Arduino, Sanguino what's the difference right? They're both AVR based with Sanguino having more I/O pins and memory. . . probably some other useful stuff as well but I'm still in the AVRTiny phase so that's as deep as my eyes can read and brain can absorb.

Going back to taking the plunge part. So I have the extruder controller with no way to test it. To get around that problem I ordered as many parts as I can to complete the electronics portion of the Repstrap build. Once all the components arrive I will give a cost summary for the electronics portion and start working on the Sanguino based motherboard.

It took a couple weeks to gather the parts and tools to assemble the Extruder Controller V2.2. The Extruder kit was ordered from makerbot.com. The Fisher Scientific isotemp hotplate was found on eBay and it has temperature graduation that seems accurate with an infrared thermometer. Reflow solder seems daunting at first, and I had a tendency to lay on too much soldering paste. I used the 22 gage 0.017" applicator tip and it still seems too big for the tine AVR ATMega168 TQFP chip. I worried about bridging with too much soldering past and ended up smearing the tiny pad with a q-tip in an attempt to clean up the soldering pad areas I also worried about the applying too much soldering paste for the two slight larger surface mount IC, however reflow soldering seems quite forgiving. There were a couple pins that bridged during the reflow process, but I was able to remove them using copper wicks. Visually, the result looks okay. Next are the through hole soldering. Images can be found in the image gallery.

Change of hosting service from HostingRails to bluehost with minor changes to the website update structure. HostingRails was easy to setup but just too slow.
Speed Test according to website speed test:

	Size	Load Time	Avg Speed/KB
HostingRails	1.63KB	5.18s	3.17s
bluehost	4.6KB	1.45s	0.32s

The boring details on the rails setup and the ActionMailer configuration is here.

Finding the parts for the laser cut acrylic RepStrap is proving to be quite challenging so the current plan is to build whatever component is available starting with the extruder while the rest of the components are located. It will be good exercise in SMT Soldering.

Details can be found in its project page.