I am wondering if I have the right idea. I need to connect my computer to my servers serial port for some debugging, I have no other computers that have serial ports but I have FTDI serial boards for programming some arduinos. If I connect the pins of the FTDI board to a DB-9 connector and Cross the Tx<->Rx will that work?
FTDI Chip to Serial port
computersftdiserial
Related Solutions
No firmware is needed. Copying the schematic will work.
We don't know if ATmega16U2 is damaged or not but assuming it isn't you can use it as a generic USB<->USB.
According to this FAQ
The Uno has changed that by exchanging the FT232RL chip with an atmega8u2 chip. There are a few things that are possible with this new chip but before we discuss that lets make it clear that by default, this chip acts identically to the FTDI chip that it replaces. It's just a USB-serial port!
One improvement in updating the chip is that, previously, Mac users needed to install FTDI drivers. The 8u2 imitates a 'generic' CDC serial device. So now, Mac users do not have to install a driver. Windows users still need to install the .INF file but luckily there are no drivers. This means there will be fewer problems with new versions of windows. There is no way to have a serial USB device that doesn't require an INF file in windows
So is will be enumerated as a virtual serial port, you just need to locate the port number in the hardware panel of the PC.
Also note that the Rx/Tx are connected to two pins of the header but at the same time are connected to the damaged MCU so maybe that will be a problem altough I doubt it.
(red/blue are the Rx/Tx lines)
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Best Answer
Beware that there are several versions of USB / SERIAL adapters. The standard type, and the kind you want for connection to your server's D-Sub 9 connector, will be one that comes already with its own D-Sub 9 connector. These have an internal FTDI chip that converts from USB to a serial logic level signal and then an RS232 transceiver part that converts the logic level serial over to the +/- bipolar signalling used by the standard serial port.
You will most likely need a null modem adapter between the USB/SERIAL adapter and the server computer serial port connector. A really convenient type of null modem adapter for this use looks like this:
The other type of FTDI USB to serial adapter is one that does not include the RS232 transceiver chip. These bring out the logic level serial lines so that they can be connected directly to a microcontroller or other circuit. It alleviates the need to put standard RS232 transceivers for a debug port or programming port on MCU hardware to save space and cost whilst at the same time when the usage model is for very short cabling lengths. One example of this type of FTDI adapter looks like this:
Note that is not possible to try to use a logic level serial adapter to "talk" to the standard RS232 port off your server. The voltage levels do not match and the logic level signals are logically inverted from standard RS232 signals. (i.e. the RS232 transceiver parts have a logical inversion through the part).