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Author Topic: serial port via header?  (Read 4579 times)

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Offline JessXeTopic starter

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serial port via header?
« on: June 05, 2008, 09:44:07 AM »
Hello everyone.  My name is Jesse I'm a sophomore in college majoring in computer engineering and I'm new to the forum and to robot building but very excited to get started.  I'm starting off with the $50 robot project and have ordered my parts.  While waiting for the I'm trying to figure out what route to go to get a serial port for my computer.  I know two options are to get a USB adapter or add a card, but I believe my motherboard may have another option.  It has something called a "serial port via header".  An image from the board spec is included as an attachment. 

I think this means that I could just use some wires and pins or something and map my serial connection to this part on my board.  Am I right about this?

Thank you!

Offline Rebelgium

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Re: serial port via header?
« Reply #1 on: June 05, 2008, 02:26:18 PM »
yup, it looks like you're right.
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Offline pomprocker

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Re: serial port via header?
« Reply #2 on: June 05, 2008, 02:46:18 PM »
what does the manual for your mainboard say?

make sure it can handle +/-12vdc for rs232


Offline JessXeTopic starter

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Re: serial port via header?
« Reply #3 on: June 05, 2008, 05:39:44 PM »
for some reason my manual doesn't specify that.  It does say that it supports 115.2 kbits/sec though.   

Offline JesseWelling

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« Last Edit: June 06, 2008, 01:56:46 AM by JesseWelling »

Offline Admin

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Re: serial port via header?
« Reply #5 on: June 07, 2008, 05:52:01 PM »
Interesting . . . I'm fairly sure you can directly hook the Tx pin on your microcontroller directly to that Rx pin on your mother board, and vice-versa.

Check the datasheet to make sure it can handle TTL signals.

Offline JessXeTopic starter

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Re: serial port via header?
« Reply #6 on: June 08, 2008, 02:45:31 AM »
It worked!  I took a ribbon from an old harddrive to create a connector to the pins on my motherboard and just stuck them into the slots on my programmer, I was able to program the ATmega with no trouble.  I also didn't experience any delays with ponyprog.  Only issue I have now is that my LED doesn't light up, and that I need to rebuild the chassis.  Thanks for the advice everyone. 

Offline dunk

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Re: serial port via header?
« Reply #7 on: June 08, 2008, 03:44:33 AM »
yup.
all you need to make these headers on PC motherboards is the correct cable with the header plug at one end and the serial DB9 connector at the other end.

a few years ago all new PCs would come with this cable preinstalled but these days so few people have need of the serial port that it is often skipped.
you can still buy the completed cable in most shops that sell computer parts.

Quote
Interesting . . . I'm fairly sure you can directly hook the Tx pin on your microcontroller directly to that Rx pin on your mother board, and vice-versa.
nope. i'm afraid not.
the serial header pins on the motherboard are full spec RS232 so are correct for connecting to devices designed to plug into PC serial ports (like your AVR programmer)
not TTL UART devices (like the UART on an AVR).


dunk.

 


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