Using com port (usb adapter) as a means of sending arbitrary signals to pins, is it possible?

Question

linux

OS Ubuntu 13.10, usb->com adapter.
I would like to use the com port for flashing LEDs, reading analog data and other things. Is this possible, and if so, where to dig?

Answer 1

Hm. As far as I know, the situation is this: if you want to use some kind of passive design with a COM port over USB, this will not work. Modern usb-coms are most often built on usb-uart + uart-com, this is at best, so it is extremely unlikely that you can simply connect an LED with two legs to the port and apply power to it. Nothing will come of it with analog signals - well, there is no ADC on the serial port.
The most convenient option would be some simple MK or a debug board with it, like Arduino - from the cheapest you can try to take Arduino Serial - uses COM for firmware and communication, or take a normal one, more expensive, but with usb-uart and don't sweat it =)

Answer 2

You can try using a USB-UART like this or with bitbang . Examples below:
1
2
3

Answer 3

Please note that COM is a serial interface. Flash at most one LED. Most likely LPT will suit you.