I have a small device that has a 3.5 mm jack for the serial connection. The protocol is uses is known so I don't have to worry about figuring that out. What I am having trouble with is figuring out how to physically hook it up.

Is it as simple as:

Device TX ---> Arduino RX
Device RX ---> Arduino TX

The device runs on a small coin cell battery so am almost sure the voltage levels will be the same.

  • \$\begingroup\$ You could start telling us what is this protocol, so that we know if it's bus-like or master-slave, or so... \$\endgroup\$
    – clabacchio
    Feb 19 '12 at 17:57
  • \$\begingroup\$ It is a standalone device with no slaves. \$\endgroup\$ Feb 19 '12 at 18:00
  • \$\begingroup\$ You need to find out whether the device expects TTL levels or RS232 levels. Otherwise, you could damage it. \$\endgroup\$ Feb 20 '12 at 2:04

If, as you state, you now the protocol and have confirmed the voltage levels to be compatible, then yes, the hookup should be simple.

You will need one additional wire however, that is the ground wire. Presumably your 3.5 mm jack is a stereo jack (two signal wires plus ground).


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