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Project Help and Ideas » Any circuits for a USB to Serial TTL converter?

August 10, 2013
by Pew446
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Hi all. Does anyone know of a circuit I could build to convert USB into Serial TTL for communication with my NerdKit? It'd be handy to be able to make a couple converters for my projects. Sure it'd be easier to just get on Ebay and buy some converters, but wheres the fun in that? :P Thanks!

August 10, 2013
by Noter
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USB is not a simple conversion to Serial TTL. Best to use a chip like the FT232R.

August 10, 2013
by Pew446
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Is this the same chip they would use in things like phones? Thanks for the info :)

August 10, 2013
by Noter
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I don't think so. Phone chips probably have built-in USB support like the AT90USB162. The FT232R is similar to the pl2303 used in the nerdkit cable but with some different features. I prefer the FT232R over the pl2303 but a chip like the AT90USB162 is pretty cool too.

August 11, 2013
by Ralphxyz
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I wonder if the AT90USB162 has a USB2 or USB3 Transcevier?

That would be fun to play with.

Ralph

August 11, 2013
by JimFrederickson
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USB is a standardized combination of Hardware and Software.

There is NOT, technically, just a circuit that can be made to convert USB to Serial TTL.

Since you are looking for the "fun of it"...

What you could do is to use your AVR Microcontroller as heart of your "USB TO Serial TTL" converter instead of purchasing a chip that is designed specifically and solely for that purpose...

If you go that approach the best place to start is here:

V-USB

This is software to enable an AVR to be a USB Device. This implementation is "specifically software based" so it can be used with almost any AVR. (The AT90USB162 from Atmel is specifically designed as USB Device and contains built-in hardware/software to enable USB Functionality.)

As far as the electrical/circuit side goes...

Circuit wise it doesn't take much to adapt a Microcontroller to become a USB Device. It is only 6-8 parts to interface an AVR to USB. (Check the links on the aforementioned site. Many of them have Schematics.)

Lots of possibilities...

This project is also very interesting for the USB Interface part as well as for it's interesting UI. (Plus there's a kit so you could start with something that is known-to-work...)

Stand-alone USB Logger

NOTE: I would GREATLY recommend that you attach your "USB Probject" to your computer through a Powered USB Hub...

That way if you do something wrong you will, potentially, blow a port on a USB
Hub rather than your Computer Motherboard...

August 11, 2013
by Pew446
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Thanks Jim! I'm going to play with this and see what I can come up with. Also, good tip on the USB hub.. Knowing my luck, I probably will blow a port in my adventures.

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