TTL Output on CMU Board

[Tom Bottiglieri]

I see here (http://kevin.org/frc/CMUcam2_workbook.pdf) there is a TTL port right on the CMU board.

Does anyone know why we get have to convert RS232 to TTL?

I have 2 theories, can anyone back these up with some facts?

A) The cmu board speaks RS232 natively, and the onboard conversion process is slower than the other converter chip (supplied to us by IFI)

B) It costs less to get 1200 RS232->TTL converter boards than 1200 4 pin female to female cables.

[Alan Anderson]

Can you be more specific about where on the camera you found a TTL port described? The workbook you linked to doesn't seem to mention it.

[Joel J]

I saw that also. It was on page 17.

[Tom Bottiglieri]

Can you be more specific about where on the camera you found a TTL port described? The workbook you linked to doesn't seem to mention it.
Sorry about that. As Joel said, its in the diagram on page 17.

[Joe Hershberger]

Sorry about that. As Joel said, its in the diagram on page 17.
You can use it to talk directly to the RC without the TTL converter. See page 19 of the same manual. Just make sure you get the pinout right on the port.

Cheers!
-Joe

[Tom Bottiglieri]

You can use it to talk directly to the RC without the TTL converter. See page 19 of the same manual. Just make sure you get the pinout right on the port.

Cheers!
-Joe
Yeah, I thought you would be able to do that. Thanks for the cite.

But, I was wondering if anyone knew the direct reason for teams getting the TTL converter board and not just a straight patch cable?

[Phalanx]

As I understand the specifications on the camera, when using the TTL interface on the camera board itself, it's speed is limited to 9600bps. When using the serial adapter your speed is 115k bps. As far as I can tell, that is the only difference.