seeking for your wisdom regarding dev boards

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kjbaik
 
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seeking for your wisdom regarding dev boards

Post by kjbaik »

Hi,

I have a question about relatively cheap hobby dev boards out in the market. While Arduino is probably the cheapest one we can find, there's also higher end dev boards like, Make Controller and ROBOstix, for instance. The former uses an AT91SAM7X256 which is an ARM7 chip, and the latter uses an ATMEGA128.

So, if you look up the price of the chip on digikey, the chip itself doesn't cost a lot more than our little friend ATMEGA168 (less than double the price). However, the dev board costs 5+ times more than the arduino board. I would like to know if this is simply a supply-demand issue?

The expensive dev boards basically consist of voltage regulator, filter caps, a little bit more resistors... nothing new or remarkable.

what do you think, ladyada?

p.s. would you be interested in developing a UC3 dev platform? The chip is also from ATMEL which is as cheap as atmega328 but has 32bit capability with faster mips. I would be interested in using one in my control algorithm studies if you invent a dev board for us. ^^ I'm sure a lot of people hate to program kalman filters and state estimators in an 8 bit chip.

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westfw
 
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Re: seeking for your wisdom regarding dev boards

Post by westfw »

While Arduino is probably the cheapest one we can find, there's also higher end dev boards like, Make Controller and ROBOstix, for instance. The former uses an AT91SAM7X256 which is an ARM7 chip, and the latter uses an ATMEGA128.

So, if you look up the price of the chip on digikey, the chip itself doesn't cost a lot more than our little friend ATMEGA168 (less than double the price). However, the dev board costs 5+ times more than the arduino board. I would like to know if this is simply a supply-demand issue?
Huh? Arduino: $30. Maker Controller: $110. RoboStix: $50. I don't see any 5x differential?
The expensive dev boards basically consist of voltage regulator, filter caps, a little bit more resistors... nothing new or remarkable.
The Make Controller price includes the Applications Board as well, which has ethernet, motor drivers, and fancy connectors.
To some extent, you can estimate manufacturing costs by counting pins. Even though the ATMega128 is only $5 (say) more than the Arduino's atmega168, the greater number of pins needs a more complex and more expensive PCB (and the roboStix has several additional chips.) (And the Make Controller requires multiple power supplies and "other stuff", and is a two-board solution.) So it's more complicated than it seems. The last time I added up te features on a Make controller/app board compared to Arduino plus equivalent shields, the Make controller was not such a bad "value" at all (IF you need those particular features.) (overall cost wise, it's really difficult to sell a board in typical hobbyist quantity for $30. But on other forums I've heard the Arduino called "overpriced" based on the low feature count (compared (I think) to things like the Atmel Butterfly (which of course is subsidized by Atmel...))

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kjbaik
 
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Re: seeking for your wisdom regarding dev boards

Post by kjbaik »

Thanks for the reply. For the cost of the dev boards, I was comparing a Freeduino version of the Arduino which would cost around $20 or even less, with the others. But as you said the official Arduino will make the comparison different. I also noticed there were much more chips on the back side of the Make Controller's ARM breakout board, and now.. I can agree with the price of additional peripherals and extra PCB overhead.

Now that I can do almost whatever I want using the arduino platform with custom software (not the arduino sketch), I want to expand my area of interests from the good old main() & ISR() routine to preemptive real-time schedulers. I am looking forward for a larger platform that I could study Real-time OS. Any recommendations for the OS?

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ran talbott
 
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Re: seeking for your wisdom regarding dev boards

Post by ran talbott »

If your interest is more in learning the software than in building compact embedded systems with ease of connecting custom hardware, you could just fish an old PC out of the dumpster, and put Linux with some of the hard realtime kernel mods on it.

There are probably some teaching-oriented lightweight RTOSes that engineering and computer science profs have written for their students that you can download and run on a minimal desktop or laptop.

The QNX folks were making their "n-2" (or so) version available free for hobbyist use for a while. I'm not sure whether they're still doing it or not. It's a widely-used, well-respected RTOS used in many commercial products. You can dual-boot it on a PC. They were even doing a port to 2000-vintage IPaqs (not so hot for connecting custom hardware, but extremely compact for a full-featured system with a GUI). You can put Linux on an iPaq, too, but it's very PDA-oriented, and I'm not sure whether anyone has even ported the realtime patches to it.

uCOS is popular, free (for non-cmmercial use. Though I'm sure the develpers would appreciate it if yo bought one of their books about it :D ), and available for various platforms. The Netburner is built on it (plus a nice library of routines that make it easy to do Internet-based applications). Their $100 starter kit is not a whole lot more expensive than buying an assembled Arduino and Ethernet shield, but you get lots more CPU power and RAM. However, it doesn't have the same kind of I/O features (like A/D and I2C), so it's a complement to Arduinos, not a replacement.

Ran

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karlgg
 
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Re: seeking for your wisdom regarding dev boards

Post by karlgg »

QNX does indeed still have a free Neutrino license for non-commercial use, and apparently some bits have become open source (though I haven't rummaged deep enough to see what they are).

http://www.qnx.com/

Sadly, there's ARM and SH4 but no obvious AVR support. Yet! :)

kc4zvw
 
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Re: seeking for your wisdom regarding dev boards

Post by kc4zvw »

How about embedded Linux on AVR32 (AT32AP7000):

http://www.atmel.com/dyn/products/tools ... ol_id=4102

This board has plenty of I/O options and memory expansion.

regards,

David

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westfw
 
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Re: seeking for your wisdom regarding dev boards

Post by westfw »

There is also the "BeagleBoard" - a high end TI ARM-based system that runs linux (and presumably could run other things.)
But hacking a minimized linux on an old x86 PC begins to look pretty attractive, cost-wise. Or see some of the "run linux on your wireless router" projects (DDWRT, OPENWRT); these tend to focus on using linux to route packets, but they could do other things. These will all be a bit short of "real hardware" connectivity (motors, analog inputs, etc.)

"Serious" real-time systems (QNX) are overrated, IMO. You pay a high price in both performance and complexity to get those "guarantees" of response time...

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kjbaik
 
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Re: seeking for your wisdom regarding dev boards

Post by kjbaik »

Thank you for your replies!!

I went through all your advices and links proposed, which led to a conclusion that there seems to be no absolute choice when it comes to embedded systems. Using linux is all powerful but gives you a headache when it comes to device drivers, especially when you have to write your own, it complicates even rather simple tasks such as GPIO (PWM, digital high/low) connectivity, whereas using dirt cheap microcontrollers you can do it fairly easily. Maybe that's why LegoNXT uses an ARM chip w/ an AVR chip to create a level of hierarchy for different kind of jobs.

The beagle board seems to be more dedicated on BANNED tasks rather than on physical computing. The AVR32 is very tempting, but costly and the learning seems hard. I found that gumstix has a new product, OVERO, 600mhz SOC that also has on board adc and pwm that may meet my needs for a higher-end device. Of course MakeController seems good for me too.

Above all, QNX Neutrino seems interesting, especially in my case, because I have a flight simulator at my disposal for a summer project at the university I am attending to, and it is operating on QNX. In the meanwhile, I might postpone buying a new hardware and get started with QNX, and learn a bigger picture of embedded systems.

Thank you all for helping me out.

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