• Welcome to Computer Association of SIUE - Forums.
 

Arduino Dev Board (AVR-based MCU)

Started by William Grim, 2008-08-19T00:11:08-05:00 (Tuesday)

Previous topic - Next topic

William Grim

Hey, peeps.

I recently got an Arduino development board to test some circuit designs for some robotics work I'm doing, such as a Cuddlotron 3000 (for the girlfriend) and a helicopter stabilizing control system, amongst other nifty things.  I thought I'd share my experiences with it thus far and maybe get someone else interested in it.

For starters, it's a 20 MHz, 8-bit RISC-based MCU with 16 KB of flash, 1 KB of RAM, 512 B of EEPROM, and 23 GPIOs.  The dev board with the MCU in it costs $50, but a dev board with a bigger MCU (64 KB flash, 4 KB RAM, and 32 GPIOs) that is also cheaper is the Sanguino ($25 + $20 for a TTL-to-USB cable (unless you build your own)).

I know the specs don't sound like something overly impressive, but it is much more powerful than you think.  First, all the pins are bi-directional, but, depending on how you use them, not all may be available for general tasks.  The board itself sports a USB-to-RS232 converter to make programming the MCU easy, and it has pin-outs for in-system programming (ISP) hardware and serial-peripheral interfacing (SPI).  The MCU also supports a bit of 16-bit arithmetic natively, and It also supports analog-to-digital conversion, an analog comparator, and several clocks.

The SPI (whose bus speed is limited by the lower of the CPU's CLK or slave device's maximum frequency) is one of the most interesting aspects (and a lot of good MCUs support SPI).  Here's an example of how it works: while most of the MCU itself is 8-bit you can easily attach a 32-bit FPU co-processor on the bus and ship big things like FFT and trig functions to a FPU that even supports code execution and branching logic.  If you need more memory, you could also attach that to the SPI.

So, the MCU may be small, but it's powerful enough for many robotics applications.  Combined with the SPI, you can do advanced math and even image processing with a directly attached camera and a bit of clever code.  Not only this, but the AVR architecture is well supported by GCC and friends.

I'd like to continue talking about it some more, but it's late and this post is already long.  I do recommend checking it out if you want a cheap MCU to get started with personal robotics or DIY projects such as controlling your home appliances, RF controllers, etc.

Oh, and for a quick demo of how to use GCC and avrdude (the binary image uploader) to write some C code and get it on your Arduino from FreeBSD, check http://www.arduino.cc/playground/FreeBSD/CLI.  Those instructions should be easily transferrable to a Linux machine, with the output device in avrdude going from /dev/cuaUX to one of the tty USB devices in your /dev.

If you have any specific questions, post them, and I'll do my best to answer them.  If I fail, you can always post in the Arduino forums.  And no, I'm not paid by them; I have just found it to be a useful tool.
William Grim
IT Associate, Morgan Stanley

GeratorZer

    I think the information that I got in this discussion will be a big to my problem.,


________________
Refrigerator water filter

William Grim

Yeah, it will be a big to the problem.  I'm glad I solution help.

If you ask me, I think that SMF itself is being exploited.  Maybe we should upgrade or drop SMF and move to something else?  Xoops didn't seem to have this many issues.
William Grim
IT Associate, Morgan Stanley

Shaun Martin

At least now I know where to look when I need refrigerator water filters.
Shaun Martin
SIUE Alumni
Associate IT Analyst, AT&T Services, Inc. St. Louis, MO.

raptor

User deleted... but I'm leaving this conversation just for the humor.  I think I may research some better security measures, this is ridiculous.
President of CAOS
Software Engineer NASA Nspires/Roses Grant

William Grim

I think SMF is probably the problem.  I would research issues in SMF exploits and see if a lot of them are being reported.  If that's the case, maybe we should go back to Xoops?
William Grim
IT Associate, Morgan Stanley

raptor

#6
I am actually extremely familiar with internal workings of SMF, and I'm thinking I may be able to implement some sort of increased security method.  I'm just not sure if these are bot attacks though.  It seems like people with ads in their sigs are adding accounts and posting one or two semi-intelligent responses, just in broken English.   :lame:

They appear to all be from Pakistan and the Philippines etc.  I thought about making an ip check part of the account creation process, but I fear we could block valid users. This of course doesn't stop them from using a proxy. Maybe we could add an extra step for people from far away, including an administrator/moderator accepting them first.

Thougths?
President of CAOS
Software Engineer NASA Nspires/Roses Grant

Gregory Bartholomew

I think these attacks are just on the rise in recent years.  Xoops was having these problems as well; though not as bad but again, I think that is just a matter of the times more than the software.  I was turned off to Xoops when they hadn't released an update for a span of about four years.  It looks like they have finally released one though (I was starting to think the project was dead) so I guess going back to them is a possibility (a lot of work though).  It may be that SMF is being targeted simply because it is popular.  I think I will try to make some small change to the captcha code and see if that cuts down on the problems.

gb
......

raptor

I'm with you Greg,

I don't think the change is worth the effort.  If there was a gain it would be minimal and not worth the effort on both your part or the users. 

In regards to captcha's.  Based on the nature of these "attacks" I'm not sure they are bots.  I.E.  captcha difficulty may not help.  Thoughts?

Scott
President of CAOS
Software Engineer NASA Nspires/Roses Grant

Gregory Bartholomew

#9
How about a short English grammar exam on the registration page.  :lol:

There is a small possibility that some of them are actually bots.  There was a lot of news recently about bots getting better at breaking captchas.  They were targeting Google at one point and generating massive numbers of spam email accounts.  They go for whatever they can that will give them the most bang for their buck so to speak.  Because SMF is so popular, there may be a group out there that specializes in writing bots that can beat SMF's captcha.  If this is the case, all we need to do is make a trivial change to our captcha so that it is different enough from the standard that the specialized bots will not be able to figure it out.  What I really want to do is change the fonts that are used.  If you want to help, see if you can find some free, heavily styled font and convert it to the "gdf" type such that I can put it in CAOS's fonts directory (I'll need the individual letter gifs as well).  If you do convert some obscure font, email it to me (I don't want some would-be hacker to download the zip from our site and add it to their arsenal).
......

raptor

Different fonts would help against bots.  But again, I'm not sure these are bots.  Marks Sands also suggested to me some further method of an "intelligence test," though didn't have any particular ideas off the top of his head.  I will say this much.  I will hand out a FREE caos binary tree T-Shirt to anyone who finds and interesting and working solution to this little nuisance.

Scott
President of CAOS
Software Engineer NASA Nspires/Roses Grant

raptor

I'll Move this convo to a PROPER thread :)
President of CAOS
Software Engineer NASA Nspires/Roses Grant

raptor

Normally would delete this, but I think it might be relevant enough.

Scott
President of CAOS
Software Engineer NASA Nspires/Roses Grant