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Freebander
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Registered: 07-2009
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Re: Arduino project chat


Many thanks for the link, its cheap...

But I wont spend five euros here, and another five euros there... At the end it will be more expensive than ordering the Arduino board lol

The challenge is to build it from recicled parts not allways been the same specifications as the arduino board. I mean, "A poormans arduino board..."

Talking about this 18Mhz xtal instead of 16Mhz xtal as per arduinos board. Question, If you replace your 16Mhz xtal in your arduinos board by a 18Mhz xtal would the board still works?

If the answer is: "No, youll have to modify the bootloader..." Then Im getting in trouble...

73 de Juan
14/Jan/2011, 5:45 pm Link to this post Send Email to 30fb001   Send PM to 30fb001
 
26FB1981 Profile
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Re: Arduino project chat


Atmel devices are not the easieast things in the world to program, if you dont have the right software. I know,.......ive tried emoticon

TBH the best thing you can do is buy an Arduino. They can be bought quite cheaply ( far cheaper than trying to program something that will only talk to its own dedicated software)
I can see exactly where you are coming from with wanting to do your own, but at the end of the [sign in to see URL] it IS cheaper and a whole lot stressful just to buy the thing already built emoticon

Have a look at this

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See this too

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Last edited by 26FB1981, 14/Jan/2011, 9:19 pm
14/Jan/2011, 9:18 pm Link to this post Send Email to 26FB1981   Send PM to 26FB1981 Blog
 
30fb001 Profile
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Freebander
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Re: Arduino project chat


Si, youre right.

But, a week ago I didnt know what was the meaning of "Arduino". Today, Ive got some troubles to solve and a project to to finish. Im happy.

Perhaps, I hope so, this post could help somebody or clarify some concepts. I would be very happy to have a brand new KENWOOD TS-590 in my shack, but since a youngster I enjoy a lot much to solder a KIT...

So, just I begun to wire the breadboard.

From left to right: 7805 , MAX232 and NE555.
(NE555 could be an option to xtal, just as RC oscilator...)

The bad news are that my local shop wont have the ATmega available till next tuesday, the earlier...

73 de Juan (Did I told you that I was born under TAURUS???...)

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14/Jan/2011, 11:21 pm Link to this post Send Email to 30fb001   Send PM to 30fb001
 
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Freebander
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Re: Arduino project chat


Hmmm...

forget the 555, it`s only really stable up to about 500KHz, although they Can go up about 2MHz they suffer badly from thermal instability, 16MHz is Well beyond the range of the humble 555.
there Are boards that use a 20MHz crystal but I think the bootloader is a bit different to the 16MHz ones to compensate for the change in serial Baud rate, so if your is set up to work on a 16MHz clock, and you put an 18 on there, your 9600 baud will be 1/8`th faster than it should be, this can cause problems for some applications, also the Timers in there in Miliseconds will be running too fast, so "Delay 1000" will no longer be exactly 1 second, but Less than this.
look, I have an idea! wait until I get my crystals arrive, and I`ll happily post you a couple emoticon
I understand your motives and they are admirable, but you need to temper this Practicality as well emoticon

personally I plan on buying the Arduino Uno, and some ATmega 328 chips, I can then program them on the Uno, and them remove the chip and put it into my own cct board.
the Uno is great because the CPU is removable emoticon
so you can prototype all day long until you get it perfect, pop the chip out all ready and programed for your application, and put a brand new blank chip into the Uno again and start a new project.

the arduino s/ware even allows you to put the bootloader onto a Blank ATmega chip as well.
I did see a tutorial about doing exactly what you are trying to do, i`ll have a look around and see if I can find it again for you.


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Freebander
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Re: Arduino project chat


Many thanks.

The 555 has been removed. lol. My exeperience is very limited and your suggestions are very much wellcomed.

If the only problem would be the timer in some aplications Ill very very happy, just adjust [sign in to see URL] the timming factor.

"the arduino s/ware even allows you to put the bootloader onto a Blank ATmega chip as well."

This is my main affraid. I ordered an ATmega328 with bootloader. If the bootloader included its not compatible with my board, beacause the 16/18Mhz xtal,I wont be able to read/writte that chip, I wont be able to burn another bootloader.

Is this correct?

73 de Juan

15/Jan/2011, 7:58 pm Link to this post Send Email to 30fb001   Send PM to 30fb001
 
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Freebander
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Re: Arduino project chat


quote:

30fb001 wrote:

 I ordered an ATmega328 with bootloader. If the bootloader included its not compatible with my board, beacause the 16/18Mhz xtal,I wont be able to read/writte that chip, I wont be able to burn another bootloader.

Is this correct?

73 de Juan




I really don`t know in all honesty, this is uncharted territory for me, and I`m basing my worry on Logic, since all CPUs/MCUs base their timing on a reference clock of some description, then Changing this clock freq will by logical deduction change the entire thing, including it`s reference as to what 9600 baud is for instance.
I don`t know how "forgiving" the comms s/ware is, so I really cannot answer you definitively.
this truly is a "suck it and see" experiment emoticon
there Are many varieties of arduino boards however, and you can through the s/ware Set what board it is you want to write to, and so it`s Perfectly possible that there is a board that uses the same cpu at different clock speed.
having said that, the only other that I have encountered is a 20MHz version, so again, I really cannot say with any confidence that this will work either.

but of course, you Must Try! this is a great way to learn emoticon

remember, there is No Such Thing as a "Failed Experiment", only More Data!

all the best my friend emoticon




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Freebander
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Re: Arduino project chat


Its going to be a little more challenge.

The COM port (RS232) at my old laptop doesnt work. Its dead, kaput, nada, niente.

So, again looking in my junkbox I found an USB->RS232 adapter. (I dont know the chipset).

To interface my laptop to the ATmega chip Ill do it via the USB/RS232 adapter, then via the MAX232 chip to get the TTL signal needed for the ATmega.

Si, I know, Its going to be a miracle if it works...

73 de Juan


18/Jan/2011, 7:17 pm Link to this post Send Email to 30fb001   Send PM to 30fb001
 
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Freebander
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Re: Arduino project chat


Best to look up what lead it is you have, some output to TTL directly and don`t need the MAX232.
I have a couple here that do that, in fact, unless it`s a Large converter (physically), it`s unlikely to bring the USBs 5v up to the 12v serial potential anyway without a DC to DC converter.
so check it 1`st, it May save you a lot of work emoticon


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Freebander
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Re: Arduino project chat


I just did an experiment that may offer some encouragement for you, I have a USB to Serial lead thats used for my servo controler, it`s USB one side and a small 4 pin telephone plug on the other, with GND, +5, RX and TX, as the pins, it Also works well with the arduino s/ware, just remember what port it`s seen as by your computer and then select that in the arduino s/ware, it Will use it happily emoticon


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19/Jan/2011, 8:53 am Link to this post Send Email to YT2095   Send PM to YT2095 Blog
 
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Freebander
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Re: Arduino project chat


Hmm... found this:

"ATmega168 chips have an internal oscillator which can be enabled; it runs at about 8mHz, which is half the speed of most Arduino boards (with the exception of Lilypads). The internal oscillator is guaranteed to be calibrated to within 10% (which is not tight enough tolerance for guaranteed good serial communications). In my experience, the factory calibration at 5v has always been fine for uploading programs, but YMMV. I wouldn't use the internal oscillator for Important Things Which Need To Speak Serial, however. For blinkylights it should be just fine though.

Arduino chips with the bootloader pre-loaded that I've found always run at 16mHz, and these will require an external oscillator. If you don't have access to an AVR programmer, you will probably want to buy a pre-loaded Arduino chip. I highly suggest Ada Fruit Industries as a source. "

taken from: [sign in to see URL]


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