5v Serial-OUT to 3v Serial-IN - with simple resistor voltage divider?

I have a generic question.

I have a case in which I will be sending Serial data @9600 baud to an Arduino slave device.
And that slave device is a 3vdc device
The transmitting device will more than likely be a 5v device.

Is it really necessary to use a voltage converter for that?
I'm thinking a resistor divider might be fine?
Or even a series resistor?

I would appreciate any words of wisdom on that question?

A resistive divider is fine, maybe 10k for the bottom resistor and 5k for the top resistor. The junction goes to the Rx of the 3V3 device, the Tx of the 5V device goes to the top of the 5k resistor, with the bottom of the 10k resistor to ground.

Thanks I thought so! :-]

If you want reliability, use a level translator. The resistors may work but check the tolerances of all parts involved and how they stack up. With resistors you are at the edge!

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