Stephen's Weblog

This isn’t exactly what I had in mind with my last post (there’s another project coming up after this one), but it’ll do for now :)

I had an idea for a simple mechanical design for a quadrotor, and since I was already pretty interested in building one, that prompted me to go work on the design for it. Like with many things I do, I like to build the full stack in projects like these – so I’ve designed my own electronics for it as a first step. Some of the PCBs have come back from fabrication so I expect to make more progress with this pretty soon.

Some pictures from the PCB designs:

The three boards above are a speed controller to drive the motors, the main PCB that will collect sensor data and do control, and a plug-in module for the main PCB which has wireless (via Nordic RF chipset) and a flash chip for archiving sensor data / other general use.

For now, I’m just writing initial firmware and testing that things work, but once I confirm the design is viable I’m planning to release the design files for it.

Another interesting feature of this project is that I screen-recorded the PCB design process – I’m planning to edit the videos into timelapses and add some commentary on the thought process behind the design. I’ll post about these also once they’re released.

Armed with a blinking LED program, I set to work attempting to flesh out the rest of the software for the CNC board. I built and tested a nested vectored interrupt handler, and started trying to port my USB stack from another chip that has very similar USB hardware. As time went on though, the outlook became a bit bleak; A number of things did not appear to be working as intended on this chip, and the manufacturer’s example code included bizzare comments and workarounds for some pretty impactful bugs that weren’t otherwise documented. Not confident that I would be able to make this chip work the way that I wanted, and being less than thrilled with the ease of assembly and some of the design of the CNC Rev1 board, I decided to make a new CNC board.

My design goals would be:

• Ensure the design will work, by using chips I’m familiar with & already have code working on.
• Reduce complexity by only having one motor driving voltage, but still allow that voltage to be changed.
• Reduce the part count per motor, by consolidating components into fewer packages and taking a different design path driving the motors.

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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:

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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…

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…)

Hi again,

More projects are incoming – but I have got a few things partway done, here’s one of them:

This circuit board is  a very basic tool that I’m going to use to monitor the SMBUS data in a computer; I have some things I’d like to find in it, but I’m also curious as to what all traffic exists on this bus. I’ve already sent this board to be produced, so should have some results from it in the near future :)

I’ve also been doing some work on PC booting; I’ve written a boot sector that does some stupid stuff; still exploring this space, and I’ll talk more about it later.

Despite having 2 weeks for this, I haven’t actually completed anything notable; So I’m just going to post some WIP images of a PCB I’ve designed to do general purpose programming (Generally jtag, but also AVR)

I’ve been working out the concepts in software using the modified USB stick (as I mentioned previously) but just haven’t had enough time to allocate to it yet. Soon, though.

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