PC -> Serial commn on standalone arduino

Forum 2005-2010 (read only) Hardware Interfacing
1

I am working on a matlab script that sends data over Serial to an arduino-powered robot. I have an old Arduino NG (lowest option in the 'board' menu :P) and I tested the matlab function to send stuff to Serial port on it, and it was getting read properly with the Serial.read() function.

Now, I cannot keep the whole board on the bot, so I'm thinking of putting together a circuit with the bare necessities. I'd need the minimum atmega168 on breadboard, with the crystal, reset and caps.

Could u please suggest how and what more to put in the circuit to enable the chip to receive data over serial just like with the whole arduino board? Pl note that I use a USB-SERIAL cable from my comp to the board, and my arduino has a regular serial port, not a USB socket.

Thanks a lot in advance

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See "Cable for External Communication" thread.

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1294032124

3

That was very useful, thanks :slight_smile:

One more thing, please:
I have the connection as follows:
Computer -> usb socket -> USB to serial cable (which ends in the 9 pin male socket. I checked out the pinout of the serial male socket, http://techpubs.sgi.com/library/dynaweb_docs/hdwr/SGI_EndUser/books/Altix450_UG/sgi_html/figures/pinouts.serial.gif

So according to this, all I have to do is connect the cable to my PC usb socket, wire the TXD pin of serial socket to RX of arduino, and short both GNDs.. two connections that is. When I try to do a screen /dev/ttyUSB0 (it was working with the cable connected directly to the arduino earlier), it says 'device or resource busy... could not find a PTY'
Is ther something I've missed?

4

all I have to do is connect the cable to my PC usb socket, wire the TXD pin of serial socket to RX of arduino, and short both GNDs.

Programming the Arduino requires bi-directional communication. The TX pin of the Arduino needs to be connected to the RXD pin of the serial socket.

5

My bad. Forgot to mention, I had loaded a code to blink the led on 13 if a '1' was transmitted over serial. Which is why I thought only the TXD-tx connection was needed. Anyway, I've wired up gnd-gnd, txd(cable)-rx(arduino) and rxd-tx. Still not working :frowning:
When I'd connected the arduino the proper way, with the cable into the serial female socket on the board, the led did blink when a '1' was sent from screen