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Support Forum » Not just any cable

March 02, 2010
by treymd
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I ran out and grabbed a USB to Serial cable and I'm getting garbage from the MCU, I've been reading as much as I can, and it seems that I may have made a hasty purchase. It not only must do USB to serial but it must then convert the RS-232 voltages to the MCU safe TTL levels?

Am I getting this right?

March 02, 2010
by mongo
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There is a converter necessary to go to the USB levels and RS-232 levels.

The NK comes with a converter from USB to TTL levels. The older ones did a double conversion from USB to RS-232 and then to TTL.

I recently bought a couple of USB/TTL converters online and they work nicely. I'll dig up a pic and the info what I log in later tonight. (at work right now)

March 02, 2010
by mongo
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Here is the current link to the same converters I use...

USB converter

March 04, 2010
by BobaMosfet
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You could make your own-- it is very straightforward and is a GREAT learning exercise.

BM

March 04, 2010
by treymd
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I considered that boba, but the ICs seem to all be surface mount, and right now that scares me a little. From what I see though, you need 2 ICs, a USB to rs-232 IC and something like the max-232 I think? to convert the logic levels to TTL. The rest appears fairly simple if you can nail down a good PCB fabrication process. What process do you use? I was thinking of getting the negative resist type solution and Developer and printing out transparencies on my laser printer.

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