Hi, I have got this: http://arduino.cc/it/Guide/ArduinoPro
Can I connect an Arduino Pro board tx & rx pins on a RS232 serial port?
I haven't a FTDI Basic Breakout Board.
I have taken the vcc and gnd pins from usb connection on main board, but I can't connect the tx and rx pins on serial port.
I cannot solve this problem.
Can you help me?
Thanks
The Arduino serial is directly connected to the processor and therefore uses 0-5V TTL serial signals. Your computer port's RS-232 Serial typically uses a swing from +12V to -12V. You will need something to convert RS-232 serial to TTL 5V serial.
RS-232 Serial Communications.Mixed-signal and digital signal processing ICs | Analog Devices
You will need a circuit with something like a Maxim 232 or 233 serial driver chip in it to do this voltage conversion. http://en.wikibooks.org/wiki/Serial_Programming/MAX232_Driver_Receiver explains the function of the MAX232 chip.
Figure 5 on this data sheet http://pdfserv.maxim-ic.com/en/ds/MAX220-MAX249.pdf gives you the schematic, you only need the MAX232 and (5) 1.0uF capacitors to implement this ciruit. Then you can hook your computer RS-232 port to your Arduino.
The Arduino Severino uses components to do the voltage conversion. Look at the section that shows the DSub-9 connector. That is your RS-232 coming from the computer. You could lift this section and build your own RS-232 To TTL converter if the afore mentioned MAX-232 isn't possible. Here's the Schematic referenced: http://arduino.cc/en/uploads/Main/ArduinoSeverinoSchematic.png
The manual has the component list: http://arduino.cc/en/uploads/Main/ArduinoSeverinoManual2.pdf
