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Project Help and Ideas » FT232R USB for Nerdkit

April 21, 2011
by Noter
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I want to post this in case anyone else is interested in additional USB interfaces.

Today I have the FT232R USB chip working and it is about the easiest thing I've done so far. After wiring it up I connected to my PC using a regular USB cable and the new hardware found window opened up as it does with any other new usb device. Then after specifying the directory where I unzipped the free drivers, the installation completed and the chip was ready to use.

Absolutely no programming was needed. Just set the baud rate for the new COMn: device that installed for the FT232 and use it. And now I can use regular old USB cables which is my favorite part.

I've been running my latest nerdkit bootloader at 38400 baud on a serial port because after setting the Atmega to use the internal 8mhz clock, 115200 didn't work with my PC. Now with the FT232R I'm running the serial interface at 250k baud with the 8mhz internal clock and it's working great.

The hardest part of this project was soldering the chip onto the adapter board. The SSOP package pins are even closer than with the ATmega TQFP so it took a steady hand and lots of solder wick. I think I spent at least 20 minutes getting it soldered on the adapter but it was my first SSOP and with practice I hope to improve.

By the way, the SSOP adapter board was about $1 on ebay. Just had to wait a month for it to get here from China.

http://i.imgur.com/babBJ.jpg The yellow/green wires are the TX/RX signals between the ATmega and the FT232R. It looks wierd because the pinouts on the ATmega TQFP package are totally different than the 28 pin DIP we're used to. The switches are nerdkit standard, reset and program.

April 22, 2011
by Singlecoilx3
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Thanks for posting this info. I can see myself using this in a future project.

Singlecoilx3

April 22, 2011
by Ralphxyz
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Noter, do you have a schematic of your setup?

Ralph

April 22, 2011
by Noter
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Hi Ralph,

No, I didn't think of that. I'll make one and post it later today.

Thanks for the reminder.

April 22, 2011
by Ralphxyz
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Since you have Eagle figured out that really would be appreciated.

I can sorta see from your pictures something that I could maybe put together but having a schematic is just so much more reliable.

So thanks I'll appreciate having a schematic.

If you'd do a link to the .sch file that also would be great as the more I look at schematics in Eagle the better I learn how the heck to use it, which so far has escaped me. But I'll keep trying.

Ralph

April 22, 2011
by Noter
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Here's the schematic. As you can see it's very simple to hookup the FT232RL.

download eagle sch file

FT232RL circuit

April 22, 2011
by Ralphxyz
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Now that I understand, thanks Paul.

Ralph

April 23, 2011
by Rick_S
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Just in case you didn't know, an Arduino duemilanove has the FT232 chip onboard with a mega328p. They just use a 16Mhz crystal instad of the 14,745,600 crystal the NK uses. I built a "freeduino" from kit which has the FT232 soldered down, replaced the crystal and made a NK dev board shaped like an arduino. It works great and doesn't need the special USB cable. I just had to hook a switch up to PB0 for programming.

April 23, 2011
by bretm
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I'm not clear why you prefer this over the special nerdkit cable. I'm not saying it's not useful/fun, I'm just wondering why standard cable plus FT232R beats special cable with embedded PL2303 for only $10.

April 23, 2011
by Noter
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The nerdkit cable is fine for the breadboard but not so good for a final PCB. I guess the wires could be soldered to the PCB making it a permanent part of the finshed product but I wouldn't do that. Also, I have a pile of various USB cables collected over the years that I'd just as soon make use of.

Otherwise, like you say, it's just fun to learn how these things work.

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