Question About Voltage Dividers

I'm relatively new to building Arduino devices, so I wasn't sure if this would belong in this thread or the thread corresponding to powering larger devices. I'm in the process of building a device that will use a HC-05 Bluetooth Module to control a couple of servos. I've read the documentation on the HC-05 Bluetooth Module and it states that you must connect the +5V pin to +5V pin, GND to the GND pin, TXD to the RXD pin, and RXD to the TXD pin. All of the pins on the Bluetooth Module seem to be tolerant of input as high as 5V (because of breakout boards within the Module), with exception of the RXD and TXD pins which at most accept voltage input of 3.3V. Would it be better to use a voltage divider, consisting of a 1K resistor and 2.2K resistor, or would it be possible to power these pins using the 3.3V pin on the Arduino?

What HC-05 circuit do You refer to? You are correct that a +5 volt controller uses 5 volt level on Tx and Rx as faar as I know.
Level shifters interfaces those different logic levels but it is much more convienent if they don't need to be used. Choose Your Circuits, using the 5 volt tolerant items I would say.

The integrated circuit I chose is HC-05 Bluetooth Module VMA302 (documentation at, which I chose because it widely supported for establishing Bluetooth serial connection with Arduino hardware. I understand why you suggest choosing a circuit that is tolerant of 5V to simplify connections, but unfortunately this device is for a school project so much of my parts and software requirements are solidified and I'm concerned that if I were to order additional parts, that I wouldn't receive them in time to complete my project by the deadline.

Which Arduino board are you using? What is the baud rate between the HC05 and the Arduino? Are you going to use hardware serial for the HC05 or software serial?

Either You order ready level converters or build them Yourself.
Here is a link to that. GY-BMP280-3.3 Pressure Sensor Module Arduino Tutorial

I apologize for not clarifying, I probably should have included that in my original description. The board I am using is an Arduino UNO REV3. I am going to use software serial connection with a baud rate of 38400 between the HC-05 and the Arduino board.

The pdf that you linked shows the HC05 TX and RX connectec directly to the Uno TX and RX so i don't see the need for level shifters or voltage divider. Software serial is usually OK at 38400 but will definitely not be reliable at any faster speed.

Nearly all Bluetooth modules clearly state the connection voltages. Unfortunately yours doesn't.

Power is 3.6>6v, signals 3.3v.

This means 3.3v is not enough to power it, so don't do it, or you will deserve any strife you get. This is because Bluetooth will be running on about 3.0v.

The picture shows the Arduino Tx signal without a voltage divider but you can bet this is because the sellers don't know what they are doing, and you don't assume anything. About half the pictures on google miss the divider, but that does not alter the fact the Bluetooth signals are 3.3v. It does imply that you might get away without level shifting but, now that you know what needs to be done, there is no need to be the first idiot who gets caught out by not doing it.

All questions about type of Arduino, baud rate, and type of serial are irrelevant. You would have to be pretty desperate to buy a divider. A 1k/2k resistor pair is quite sufficient.

You might find the following background notes useful.

Sellers info info is sometimes wrong concerning the 5 versus 3.3 volt. Even projects suppported by various sights violates absolute maximum ratings. One project leader claimed that some disturbance "forced" him, but the project continued on that sight.
The only reliable data is the data from the manufactorer. Follow them and nothing will burn.