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Topic: Flashing open-wrt onto ap121u (Read 747 times) previous topic - next topic

Davepheadrus

Hi guys, new here bought the UNO today and I'm a bit of a noob with it.

I needed to buy a uart cable but figured I'd buy the UNO because it would be something to play with after the flash..

But first things first I need to use it as a 3.3v uart cable but I didn't realise that it's default is 5v, as I said I'm a total newbie to this so please a little patience and detail.

The guide I'm reading (for use with uart) tells me not to connect the power but if I don't then will it not be 5v going through the tx & rx? I want to make sure I don't brick the router is all so any advice on this will help me tons.

Otherwise should I be connecting the VCC to the 3.3v?

Thanks!

Dave

Chagrin

If you dig around on Google for "logic level conversion" you'll get some help on this.

1) Plug in the router using its regular power and the Arduino via the USB cable.
2) Connect a wire between the router GND and the arduino GND. This ensures that both devices agree on what "zero volts" is.
3) Connect the TX from the router to the Arduino RX. The router transmitting 0-3.3V signals is OK for the Arduino, running between 0-5V, to read (anything over 0.6V is considered a logic "high").
4) Connect the TX from the arduino through a resistor divider to the router's RX. This reduces the peak 5V signals from the Arduino down to the maximum 3.3V that the router can handle.

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