Inverting RS232 ttl level logic

snow · Posted: Mon Jun 04, 2018 11:47 am Post subject: Inverting RS232 ttl level logic

Howdy all.
How do you invert RS232 TTL level logic. I'm doing a bit of a hack on a PTZ camera . Im modifying it as i don't need the camera only the motorized base.
I have found the Data line between the Camera webserver and Pan Tilt control board. It uses Pelco D protocol by the looks of the data i've sniffed off it.
My problem is the voltages are TTL level and i cant use the serialout or print statement to drive it as it doesnt work.
How would i convert RS232 ttl to toggling a pin for a data stream ??

Cheers
Snow

(BASCOM-AVR version : 2.0.7.8 , Latest : 2.0.8.1 )

EDC · Joined: 26 Mar 2014 Posts: 971

It is not clear, for me, what you want to achieve.
Inverting signals means that signal from positive will became negative and vice versa. For this you can simply use some Hex inverter like 74HC00...but you probably want to level converter or level shifter.
If this camera use RS-485 line then you can use MAX485 for 5V Atmega or MAX3485 for 3V Xmega...and read about "Config Print".

Evert :-) · Joined: 18 Feb 2005 Posts: 2156

The software uart supports inverted levels

snow · Posted: Tue Jun 05, 2018 11:24 am Post subject:

Thanks.
I have broken into the data line between the camera and the motor pan/tilt control board . Eventually i want to control the pan tilt motors directly and throw the camera away. I just need the motorized platform for a project.
The camera sends data to the board as an TTL data as a pelco d protocol. If i cut the data wire and read it with tx/rx on my UNO and send it back out it doesn't work as the voltages are inverted. eg idle 5v where the cameras data is idle 0v. I was thinking at inverting the comms data voltages to see if that works. It just seems funny i can read the data but cant send it to the motor board to get it to work.

Ill give the inverted command a try or am i missing somthing??

Cheers
Snow

six1 · Joined: 27 Feb 2009 Posts: 553

did you read EVERT's hint on INVERTED