Interfacing Arduino Micro with another digital device

Projects Programming
1

I have an Arduino Micro, and an RN-52 Bluetooth Audio module that I want to control from the Arduino.

The RN-52 is a 3.3V device, and can be controlled over a UART Interface when pin GPIO9 is pulled low.

It also has an 'event' signal on GPIO2. GPIO2 floats high (3.3V) and goes low for 100 ms when an event happens. At this point I'm supposed to enter terminal mode by pulling GPIO9 low, waiting for 'CMD', entering 'Q\r', and parsing the result. I think I know how I can do that with the Micro.

With that background, what would be the best way of working with GPIO2? Should I connect it to a digital pin and use an ISR? Or is the polling of the main loop fast enough that just doing a digital read would work?

Also, since the RN-52 is 3.3V and the Micro is 5V, can I use digital inputs at all, or should I be reading an analog line? I think digital state change means 3.0V -> 0, but I just want to be sure.

Thanks in advance for any help or advice.

3

I've already got a component from Sparkfun called a 'Bi-directional Logic Level Converter' to handle the connection for the UART. It's supposed to convert the 5V to 3.3 and vice-versa, depending on the direction.

I'll try the polling route; it does seem simpler than creating an ISR, even though I've done it before.

If I use another digital pin, set it to output, and connect it to GPIO9, I guess I need a voltage divider to make its HIGH 3.3, otherwise I'll be putting 5 V into the 3.3V pin and I would fry the Arduino? Is that right?