Stephen's Weblog

Around the middle of December I decided it was finally time to make this project actually work.

I took the one CNC board I had assembled, such a long time back, and subjected it to an initial smoke test (connecting the power, that is). There was smoke. Not discouraged by the loss of a chip or two, I took a further look. I found that the assembly of the first board had hit a number of major snags; The board was 2oz copper in order to be capable of routing large current loads to the motors – but the groundplane was exceptionally difficult to solder to, even though the pads have thermals. I found that one of the chips broke because a resistor intended to keep an “enable” signal low was not connected to the groundplane, and the other one, a FPGA, was installed backwards (these FPGAs have two circles on the top which could indicate pin 1; Unfortunately the wrong one was chosen and I didn’t check.)

Undeterred, I pressed forwards with getting this board to work. I replaced the FPGA and rotated the other one, doublechecked a lot of signals (there were still some components on the back side of the board that were not properly connected to ground). All the poor connections were on the back side of the board, the top side had been reflowed and the connections seemed uniformly good there.

After those fixes and some cleanup, ran the smoke test again – The board powered up without smoke! A first small victory down this path – But many more things remained.

So, let me tell you about JTAG. I made a post on jtag a long time ago, when I was first starting to mess with it; but for this project I decided to build my own JTAG tools to program the chips involved & for other nefarious purposes.

I have made a few starts  towards my own jtag stack over time, first was an AVR-based board intended to program all manner of things – This project ultimately stagnated as the jtag level shifting interfered with actually programming the AVR chip itself. Despite a fix, building out the stack was a big project and never was completed.

While I was designing the CNC board though, I had the idea for a more specific debugging helper tool geared for it, and not too long after designing the CNC board, I did build such a device based on a chip I had come to know and love (and built a USB stack for…) – this was the ucHelper, PCBs shown below.

ucHelper is really just a minimal JTAG and serial interface board – Being exactly what I needed for programming and debugging here though, I got started on writing the code for it.

(more in part 3)

It’s been just over a year since I decided to seriously pursue building my own 3D printer, and while it has been taking a back seat to a lot of other projects I’ve been doing, it’s looking like it will finally come together in the next few weeks!

The CNC Controller in the last two posts was my first big move towards realizing the idea; Being  a stubborn sort, I’ve wanted to build the entire thing entirely myself – Historically this has been both a good and a bad decision; I like owning the entire stack in a project, but it comes at a price – Actually building and completing the project takes a lot longer. The upside is I get a lot of experience from such projects, and learn a lot about a wide variety of things – this is ultimately the reason I do it so much.

I did finally concede to use an existing 3D Printer hardware design, and near the end of last year built a Prusa Mendel from a kit of printed parts & hardware (pic below)

However I am still quite determined to own the electronics. Around the very end of 2011 I finally decided to put the effort into making this project happen, and started to bring up the CNC board I had designed.

(More in part 2)

Ah, it’s been a while.

Since I opted to stop posting on a fixed schedule, that seems to have eliminated any hope of regular updates – oh well.

So, I have been largely tied up in a (Very big) project that’s still secret, I’m not saying much about it. But there have been a few bits of progress in other areas – Most notably, I finally got a CNC controller board populated!

Isn’t it lovely?  I certainly think so, after all the work that went into getting this far :)

Sadly, I won’t really get much further at the moment (need to get back to an all-consuming secret project), but this has marked a pretty big milestone in a few of my projects (the reflow controller also works pretty nicely!)

I’ll be sure to take some time and write up these when I make some more progress (or just get sick of working on the more important stuff again)

Progress! At long last!

Over the past month I have been designing a CNC controller for various small projects I’ve been kicking around (oh things like 3d printing, building a pick&place, and some other random thoughts)

Being the hopelessly stubborn sort that I am, I decided to build it from scratch. The design work for something like this is something I enjoy immensely, and while I don’t always get everything right the first time (There are a few inefficiencies, but nothing terrible), it’s been a lot of fun and a good learning experience.

Here’s an image of the final board design, and past the break is a very long thread of text and images showing the steps getting to this point:

(more…)

Well, when I initially pushed myself into writing on a schedule, I thought having to write about something periodically would be an interesting challenge; I’ve learned a few things since then, one of which is that when I don’t have anything specific to talk about, I don’t really have anything to say either; So I’m changing the format of this blog once again to just post about project completion & milestones when they happen, rather than on a fixed schedule. Looking back the updates I’ve made are interesting from the perspective of seeing how things were going over time, but I think it will be more interesting if I’m just writing about the stuff that excites me :)

With that said, there’s nothing to  show for this week besides minor progress on a few fronts; so here’s a picture of my desk as it stands pretty recently:

Ah! It’s been 2 weeks again already; Work speed for me always varies a lot, but I’ve been unlucky lately: I put in a lot of effort for one project and then it stalled right near the end. I’ll go back and finish it and write it up sometime soon though :)

In the meantime however, I have received the reflow controller PCBs I mentioned a month ago! Some pictures are up on flickr, one is below – I don’t have it working yet but that will become a priority pretty soon.

Coming next:  I’m currently working pretty hard on a CNC controller for stepper motors and some other things; As usual my ideal is to build my own solution instead of using any existing one, so I’m desiging my own now. I will post a full writeup on it once I have it completed, but don’t want to share any details at the moment.

Projects have been moving more slowly than I anticipated, and I don’t really have time to write much, so I’ll defer this update; Will post about what I’ve been doing in (just under) 2 weeks.

Happy new year, all.

Not a whole lot has happened since my last post; at least not a whole lot of projects that I’m talking about :)

I’ve been busy working on a Windows Phone 7 game, writing VHDL for one hardware project, thinking through a second hardware project, and will be working on yet another hardware project soon ;) These I will probably post about eventually, but not until they’re further along…

Some of these projects are explicitly going to have the first revision done in 2 weeks though, so I should have plenty to talk about then!

I have started getting set up to compile code for the LPC134x chips that I’m using in everything recently, as I will need to be able to program them shortly – I’ve got the devkitARM toolchain installed and am modifying the GBA compilation toolchain to be able to compile for these devices. Just started that earlier today and not quite done yet.

I’ve also designed circuit boards for a toaster oven reflow controller (including images below) – This is a two-board solution, one deals primarily with switching the high voltage using optoisolated triacs (thanks eagan for pointing me in this direction, I was originally thinking of relays) – The other board is another LPC1342 with a flash chip to store configuration and run data. It has some buttons and an LCD for user interface.

These will be in Laen’s Jan. 3rd order, and I will be trying oven reflow very shortly after they come back :) I also have come up with a few other interesting things to control with this, and will have to report back on my success with that at a later time…

Nothing really big to show off, but a few things are moving along:

First, I’ve started a Flickr page! Pictures I take (typically of stuff I’m working on or taking apart) will be auto-uploaded to http://www.flickr.com/photos/sgstair/

I don’t always update the descriptions but any questions posted in the comments will be answered :)

Second, there has been some progress on bitbox; After some early failures, I now have the bitbox_test board working! I misread the datasheet for the LPC134x chips initially – The USB bootloader requires an external crystal; I’m not quite sure why I thought otherwise. For the bitbox I am attempting to do USB without a crystal even though the internal RC OSC might be slightly out of spec. Maybe I’ll need to revise it.

Next I’ll be writing some initial firmware for this board and then all things bitbox should start to move along.

I also ordered some laser cut acrylic for the test fixture, and should get that back in a bit over a week – this test fixture has been interesting to design – it’s a little overengineered in hindsight, I’ve since designed another fixture (for another project) that’s far simpler. Below is my laser cutting pattern with a few designs:

I’m using Ponoko to have this produced – will have to talk more about it next time.

One big thing I’ve been working on lately is bitbox! Bitbox started as just a clever idea, but it was just so interesting that I had to make it :) Bitbox is essentially a tiny music player that will play 8-bit music – sorta like a boombox, but a bit smaller ;)

I still have some software work ahead of me, but here’s the (nearly) final circuit board:

(I say nearly final because I did go on to make some tweaks after taking this image)

Read on for a train of WIP images and more information… (more…)