Unused RS232 Pins for other connection

[Urahara]

Ok, I feel that I am going to ask a very stupid question. Don't flame me if you think it is.

Pins 2,3 and 5 of a DB9 connector is used to set up a serial port for firmware upgrading purposes via a bootloader.

The other pins (1,4,7-9 of the DB9) are unused. Can I use them, ie connect these unused pins directly to the pins of the microcontroller. That way, I can reduce the number of external connectors on the main board. I can use them to connect to light up external LEDs or even a few relays.

Of course, at any one time, I either use this DB9/RS232 connector as a real RS232 device or an external LED/Relay box.

Just a thought. Thks!

 

[Nigel Goodwin]

You can use them for anything you like, but it's generally a BAD idea to use a standard connector for this purpose - what happens when (not if) someone plugs it in an RS232 port?.

 

[3v0]

I agree with Nigel.

Some of these "unused pins" are used for various handshaking signals. At the PC connector they will carry + or - 12V.

Ok, I feel that I am going to ask a very stupid question. Don't flame me if you think it is.

Pins 2,3 and 5 of a DB9 connector is used to set up a serial port for firmware upgrading purposes via a bootloader.

The other pins (1,4,7-9 of the DB9) are unused. Can I use them, ie connect these unused pins directly to the pins of the microcontroller. That way, I can reduce the number of external connectors on the main board. I can use them to connect to light up external LEDs or even a few relays.

Of course, at any one time, I either use this DB9/RS232 connector as a real RS232 device or an external LED/Relay box.

Just a thought. Thks!

 

[Urahara]

ok, point noted.