How to isolate FTDI chip from arduino hardware TTL serial?

In a project I would like to use arduino's hardware TTL serial to connect to a TTL serial device, both RX and TX. Since the RX is controlled by the FTDI chip on my arduino 2009, I am a bit hesitant to just make a direct connection between arduino RX and the device's TX. So if I want to do this, how do I isolate the FTDI chip from it so the chip won't be damaged? Thanks.

KE7GKP,

Thanks. I will keep my fingers crossed :)

The standard arduino design has 1k resistors between the FTDI and pins 0/1 to prevent any such issues.

Double check the schematic for your device; if they're there, just hook your device up and go.

-j

Great! I will run some test with two arduino then. Thanks!

Well I can think of two simple methods of completely isolating the 328p from the serial converter chip for use externally of the serial channel. Remove the 328p chip from it's socket if its not a SMD, or just jumper a wire from the reset pin to ground pin. That would force the 328p into hard reset with all it's I/O pins in input high impedance mode.

Lefty

Do I understand correctly? You have some device (other than your PC) that sends/ receives serial data, and you want to connect that to your Arduino?

There are safe, no "fingers crossed" answers. Simple answers. Not expensive answers.

Details at...

http://sheepdogguides.com/arduino/art4SeIntro.htm

tkbyd: Do I understand correctly? You have some device (other than your PC) that sends/ receives serial data, and you want to connect that to your Arduino?

There are safe, no "fingers crossed" answers. Simple answers. Not expensive answers.

Details at...

http://sheepdogguides.com/arduino/art4SeIntro.htm

Exactly! I have a panel (will have it after I get the custom PCB and assemble it) that talks serial. I want arduino to link to it to write messages to it and read key presses from it via the atmega hardware serial, because it'll make examples easiest to understand by newbies and also speed can go up to 115200.

Now I have almost completed the manual of the panel and most of the programming. I will post some results once I'm done.