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Author Topic: Arduino serial with MAX232 or equivalent?  (Read 6615 times)
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Has someone done an Arduino serial board design that uses a true rs232 transceiver (e.g. MAX232) instead of transistors/capacitors/diodes?  I'd prefer a "single sided" design, to facilitate etching at home.

I've had trouble with circuits that use the transistor trick in the past, and prefer to avoid such circuits if possible.

-j

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I started doing a version with max232 three weeks ago, based on S3v3 version, but stoped. If you want one, I think I can restart it. In a preliminary view, it will be a little bigger than S3v3 (less than 1cm.).
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Has the s3v3 been posted somewhere?  A quick google didn't return anything useful.

I'm not opposed to doing the work myself, but I prefer not to reinvent the wheel.  smiley

-j

« Last Edit: March 05, 2008, 12:32:21 pm by kg4wsv » Logged

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It just went up here: http://www.arduino.cc/en/Main/ArduinoBoardSerialSingleSided3
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I've had a max232 based design sitting in the wings for a while (it's double sided though). Anyhow, relevant details are here.
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iDuino - MaxSerial - [url=http://spi

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Nice.  Any plans to make boards or kits available?

-j

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There can always be kits smiley Back of the napkin says they'd run about $15-$20.

If anyones interested I can try to sneak a few onto next week's panel.
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I'd take a couple of bare boards, or one kit.  I've already got components (except for the regulators and the short 47uF caps), so bare boards would work fine for me (I realize probably not for most folks, though).

-j

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I am moving to the MAX232 for the Freeduino Serial V2.0

I prototyped it and it works great... 100% reliable uploading sketches.  I can share the schematics and eagle files, if anyone is interested.  The signals (RX, TX, DTR) behave a little different from the USB based Arduino signals, but it is consistent to any other MAX232 based board.
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After finalizing the BOM, these are just waiting to join a panel. (Now I need to do real work so I have something justifying a panel smiley-sad) The only strange component left is the 3.3V regulator (78L33) and the short caps.

Expect boards whenever they come back from the fab-house, and kits whenever the parts come in.

Actually, is there anyone who'd prefer I didn't use "Freeduino Serial"? There could be confusion with the existing (transistor or otherwise) Freeduino Serial boards.
« Last Edit: March 10, 2008, 11:46:59 pm by spiffed » Logged

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I think Freeduino Serial is fine.  The version number should be V2.0 or superior, as the changes from V1.0 justifies the new version number and leave V1.x for enhancements to the transistorized boards.  I am working on my serial board based on MAX232 and I am calling it Freeduino serial V2.0, which I almost finished last week... but I think I will also add the 3.3V regulator, if you don't mind sharing the idea.

BTW, what PCB design software do you use to make those nice looking 3D images of the board?
Edited: Never mind... it is Eagle3D.  I tried it and it works great!
« Last Edit: March 11, 2008, 12:38:17 am by nkcelectronics » Logged

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The version number should be V2.0 or superior, as the changes from V1.0 justifies the new version number
I think you're right, 2.x makes sense.

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what PCB design software do you use to make those nice looking 3D images of the board
I use Eagle. The 3D mock-ups come from the Eagle3D ulp and POVRay. It can take some futzing to generate exactly what you're after, but it works. I find it most useful to uncheck "parts" in the Eagle3D dialogue and use it to generate PCB only renderings like these. I know there's a Protel/Altium tool to do the same.

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I think I will also add the 3.3V regulator
I used a 78L33, simply because I have them in inventory. Sadly there doesn't seem to be a standard for 3.3V regulators, the 78L33 is only made by ST. Other manufacturers make other regulators, and you may find a better choice for you; I found most to be pricier and require larger stabilizing caps. A different regulator may have a low enough drop out to run from the 5V rail though instead of Vin.
« Last Edit: March 10, 2008, 11:49:54 pm by spiffed » Logged

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The version number should be V2.0 or superior, as the changes from V1.0 justifies the new version number
I think you're right, 2.x makes sense.
With Freeduino, it is important to add the name of the person / company making the enhancements to the board, so if two or more at the same time name a board "Freeduino serial v2.0", then the only way to distinguish one of the other is by the name (Fundamental Logic in your case).

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I think I will also add the 3.3V regulator
I used a 78L33, simply because I have them in inventory. Sadly there doesn't seem to be a standard for 3.3V regulators, the 78L33 is only made by ST. Other manufacturers make other regulators, and you may find a better choice for you; I found most to be pricier and require larger stabilizing caps. A different regulator may have a low enough drop out to run from the 5V rail though instead of Vin.
I added a 78L33 and a cap to supply 3.3V to the header, but I will leave it as an option when I sell the kits, as not everybody needs the 3.3V.  I run it from the 5V rail, as the drop out is 1.7V for 78L33...
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hey

I would even suggest something more specific, like "Freeduino Fundamental V2" or something like that.....
That way there can be  multiple serial boards, with less confusion. as we're basically talking about boutique versions, it makes sense to highlight the manufacturer name in the design.

D
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After much deliberation, these will be silkscreened as "Freeduino MaxSerial".
I've noticed most people seem to regard the NKC Electronics boards as the unofficial official Freeduinos.
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