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Author Topic: Using a cell phone cable as a cheap ($3) USB TTL  (Read 4393 times)
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Long story short, I used a cheap ($3 on ebay delivered) Nokia CA-42 cable knockoff as a USB to serial adapter for another project (adding a serial port to a Buffalo Linkstation Live Network attached storage LINK BELOW).

Would it be possible to do something similar for use with a boarduino?  Most of the cheap cables are based on a Prolific PL2303 (datasheet LINK BELOW) chipset which is supported under Windows and Linux.  

Seems like a great way to get a cheap USB to 3.3V TTL...

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Other project: http://buffalo.nas-central.org/wiki/Use_a_Nokia_Serial_Cable_on_an_ARM9_Linkstation

Datasheet http://www.prolific.com.tw/eng/downloads.asp?ID=23
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This sounds like a good idea. I bet the prices (on ebay) will jump very soon.

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It should be possible, although it looks like those are strictly 3-wire serial implementations.  That means that the auto-reset feature won't work, and you'll have to push the button just like in the good old days.
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If anyone is interested, I cut the end off of a CA-42 cable and discovered the following pinout:
yellow -> common
blue -> arduino TX
green -> arduino RX
red -> unknown

I downloaded the driver from Prolific's site mentioned earlier (2nd post). Version 1.0.2.5 worked for me in Vista x64. I was able to program my BBB freeduino and monitor returning serial data for debugging.

There are a couple disadvantages, the first being no 5V power to run the 'duino off of and second, you have to manually press the reset button. The second is actually a non-issue for myself as I don't like the auto-reset feature resetting my 'duino every time I start the Serial Monitor or plug in the USB cable or start the Arduino compiler. Then, there is the advantage of price, I paid just shy of $5 USD per cable shipped.

note: my cable runs at 0-3.3V on the TX line
« Last Edit: April 09, 2009, 09:33:28 pm by m_elias » Logged

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Nice - Just ordered one from Hong Kong - $3.24 shipped.
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Update: I found out that the usb end of my cable is not an injection molded plug, but with some prying I could pop it open. I then proceeded to solder the red wire to a +5V contact and behold, it now powers my Arduino too!! Now if only I could get the Arduino to bake me a cake....
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For those that want the 5V power or auto-reset, you may want to look into hacking one of these: http://www.dealextreme.com/details.dx/sku.2537
$6.68 shipped
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I apologize, again, for my newness.  I just read this thread (thanks westfw) and the linking pages: Does that mean I would just solder the appropriate ends of this cable to... a board...somewhere? I'm confused.

Backstory: I have an arduino project, that takes Pushbutton triggers, and sends data over the USB connection.  I'd like to make more, without buying separate arduinos for each ($30) or using boardino/BBB solutions with breakout USB ($20-$25)... if I can cut my Serial connectivity cost from $12-$15 to just $3, that's a big enough deal for me to do it, I just don't understand exactly what I would be connecting where...

Thanks guys,
Phil
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I soldered on an end that was compatible with most of the Arduino clones out there, a BBB in my case, also compatible with the FTDI cable pinouts. See the photos, the first one is the CA-42 stock, and the second is after I have modified it.

http://s655.photobucket.com/albums/uu280/m_elias_photos/?action=view&current=100_0643.jpg
http://s655.photobucket.com/albums/uu280/m_elias_photos/?action=view&current=100_0644.jpg
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when you say you soldered it to your BBB, where did you solder? I am a little lost there...
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Quote
I soldered on an end that was compatible...
See the photos, I did not solder the cable directly to my BBB, I soldered on a connector that plugs into the 6 pin header that most people would plug their FTDI USB to TTL cable or a USB BUB into.

example of FTDI cable: http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMtf8aSAtgR7DpPMdam/we00
USB BUB: http://moderndevice.com/connect.shtml
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Hi

I want to clarify something....

These USB-to-Serial cables, even if they have the PL2303 chip, are they TTL compatible?

I asked because I always thought serial port specifications are not TTL compatible...
so if it is a USB-to-Serial cable, can you just connect the serial side to the Arduino? Don't we need some form of level conversion like using MAX323?
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LiveRock, most of these cables (for example the one I linked in post #7) use the PL-2303 for USB , and a Maxim chip for the RS232 level conversion. The PL-2303 operates at logic levels that are compatible with the arduino pins. There is a datasheet here: http://user.chollian.net/~mines/pl2303.pdf
« Last Edit: May 27, 2009, 06:01:47 am by mem » Logged

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I wrote an article for uC Hobby with step by step instructions on how to
use one of the cables with an Arduino breadboard setup. I modified the
cable to provide USB power and auto-reset. Here's a link:
http://www.uchobby.com/index.php/2009/10/04/diy-usb-to-serial-cable-for-3/#more-492
« Last Edit: October 05, 2009, 12:24:42 am by yardleydobon » Logged

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