Archive for the ‘Uncategorized’ Category

Dev snapshot build 0.4.dev-20120318

Sunday, March 18th, 2012

I just pushed an enormous changeset into github master.

This is very experimental and WILL change a lot in the future.

In addition to a crapload of smaller things, it implements this (except the crafting recipe stuff):
http://c55.me/minetest/wiki/doku.php?id=roadmap:digging_time_groups
and this:
http://c55.me/minetest/wiki/doku.php?id=roadmap:content_and_engine_separation

Mods are likely to require modification. Quick info to modders: You need to specify digging time by using item groups now. For example,
material = minetest.digprop_woodlike(1.0) turns to something like
groups = {choppy=2}. (see this for the specifics. You may want to leave the old lines in there for backwards compatibility.)

“Where do I put my mods now?”: They go in
user/server/addons/mesetint/mods.
If you install it on Linux, that is
~/.minetest/server/addons/mesetint/mods.
Create that yourself; the game will do that some day but not this time.

Hint: /time 18000 will give you a nice sunset.

Beware: There has not been much testing; it may work or might not, and might or might not delete all your files, or kill your cat.

Build for Windows:
https://github.com/downloads/celeron55/minetest/minetest-0.4.dev-20120318-win32.zip

Latest commit:
https://github.com/celeron55/minetest/commit/fb3ac49335496e3ebc4601a58d6afb356d7b42d2

Programming. How do you learn it?

Monday, February 20th, 2012

Here is something I got asked by somebody called Keith in a recent comment:

Thanks for making this code available. I am interested in taking a look for hobby purposes. I also have an engineering background, and when I was at University studying mechanical engineering most of the people in my class could not program to save themselves; I found I had a knack for it and now develop engineering software for a living. Where did you learn your programming skills if not in your current line of study?

I initially thought to reply in a private e-mail, but then I thought I’d post here, because I could think of somebody else asking the same thing. Here goes:

I have been programming a lot as a hobby, and for a bit professionally, since being 13 years old or something… and less since basically forever. I wrote a few lines of BASIC at the age of 9 or so I guess. At the age of 12 I made websites. They were ridiculous by (almost) any standards, but I learned a lot. Also I was having fun with CoolBasic shortly after.

Nobody really taught me, but there was a humble C++ course in secondary school and my family didn’t view the hobby as too bad a thing. More importantly I found some programming related communities and some programmer friends on the internet at that time.

Similarly I learned electronics. Found people and friends on IRC who are interested in that stuff and then designed and made stuff together.

  • “You think this’d be awesome?”
  • “Not sure if we’d be able to pull that off… but sure, let’s try it!”

That. Repeated so many times. Minetest isn’t much of an exception.

And I can program pretty much anything on any platform, unless the problem involves very complex math. Most things don’t.

Making Minetest really isn’t /hugely/ a matter of pure coding skill though; it’s mostly a matter of determination, and now as being largely a community project, it’s much about managing other people’s doings. Also a difficult thing is to take pauses in development of the correct length to not become bored while still keeping other people interested.

// c55

dcdrive2 phase voltage in oscilloscope

Sunday, February 19th, 2012

dcdrive2 is a BLDC(sensored/sensorless)/universal motor speed controller I made about two years ago. Mostly for fun, experience and for the possible uses in combat robots.

Here’s a random photo of dcdrive2 turning a BLDC motor at full speed I took today. It is a sensorless R/C car type motor. The waveform looks pretty much exactly like what a properly working BLDC controller should produce.

dcdrive2 phase voltage oscilloscope shot

Oscilloscope image of dcdrive2 doing it's work

The strict limits of this design is about 10 to 45V of operating voltage (depending on regulator, FET driver and capacitor configuration), and it can supply at least 45 amps (haven’t really been able to test more, after some recent modifications).

dcdrive2

dcdrive2

Here’s a schematic of a version of it, for those interested.

Basically there is an AT90PWM3B (an easily programmable AVR (just like any atmega, but with a capable 3-phase bridge PWM controller)), a 3-phase MOSFET driver (IR2136x family) and the MOSFETs (I’ve been using IRF1405N).

The initial prototype used two DIY PCBs, the other being the high-current board and the other one containing the logic. Here is a shot of a testing setup on an RC car, including 22.2V worth of batteries:

dcdrive2 prototype testing

dcdrive2 prototype testing

The final version uses a robust 4-layer PCB with thick copper layers and as good withstanding of high switching current as I could possibly come up with. I have a few boards laying around and could order more fairly cheaply, if somebody is interested.

I haven’t been able to accomplish proper load testing for it, because I don’t own large enough motors or vehicles or test benches that could stress it to the extent it should be able to withstand, but as for what I have been able to do, the power parts of it don’t seem to even know what failing means. 8)

Normally it is controlled using an RC servo PWM signal. I have also used it as the sole controller in a “melty brain” style fighting robot. This is pretty lightweight usage of it:

Also it is used for controlling the power in this one. Albeit not being brushless, this uses much of the voltage and current capacity of it. I think this was with a 45A current limit.

Dev snapshot build 0.4.dev-20120106-1

Friday, January 6th, 2012

Build for Windows:
https://github.com/downloads/celeron55/minetest/minetest-0.4.dev-20120106-1-win32.zip

Latest commit:
https://github.com/celeron55/minetest/commit/569156b01302ea4ba45d11ff5524b62dbc6a9aa0

Some random fixes and a few small additions to modding API.

Dev snapshot build 0.4.dev-20120102-1

Monday, January 2nd, 2012

Build for Windows:
https://github.com/downloads/celeron55/minetest/minetest-0.4.dev-20120102-1-win32.zip

Source / last commit:
https://github.com/celeron55/minetest/commit/48131bf988be2261d7abfab05ee4c41a3b002ad4

Mostly modding API and other under-the-hood stuff.