I have a Bluetooth module that needs 3.3 volt for transmit and recieve. My arduino is 5 volt. I want to power the arduino externally with no USB connected so the 3.3v out pin will not have any voltage due to no power coming in through the ftdi chip. The level converter I have from sparkfun needs a low and high voltage. Any suggestions on where to get the 3.3 volts?
Donny
no power coming in through the ftdi chip
Unless you using a Nano or Duemilanove, there is no FTDI; there is an onboard 3.3V regulator.
How are you powering the Arduino? 3xAA battery into 5V pin? 2x3.7V LiPo/Li Ion into the barrel jack?
Both will power the 3.3V regulator.
Does the Bluetooth need 3.3V max on its Rx line (so the Tx from the Arduino needs to be converted down, simple way with 2 resistors if speeds are not high).
Yes I am using a nano. Power is through a 12vdc lead acid battery. Power into vcc.
Application is a 3 axis camera slider ran from a android tablet. Jogging through the tablet. So I would think speed would be a concern. That's the reason I went with the level converter instead of resistors. The level converter is from Adafruit not sparkfun as I stated before.
The bluetooth is a hc6 version 1.05. It just says 3.3vdc for the rx and tx lines.
Do you think I can do the resistors given the application or do I need to add a separate voltage regulator?
Donny
FTDI chip is only good for 50mA. How much does the bluetooth need?
Resistors should be okay. You're not at MHz speeds on serial port. Go with 2.5K on Tx pin & 5K to Gnd, junction to the Rx on Bluetooth.
Hang on, you say:
DonnyM:
I have a Bluetooth module that needs 3.3 volt for transmit and receive.
If it "needs" 3.3V, then it must be running from 3.3V. Or at least part of it is running from 3.3V
So your source of 3.3V is whatever part of the Bluetooth module is operating at 3.3V. There will be a connection for it.
See, that was easy, wasn't it?
Not sure what the current draw of the TX and RX lines is. They are CMOS logic gates so very little. 20 to 40ma for the whole device at 3.6 to 6v.
Interesting idea to use the 3.3v on board. Now where to find that. I seen a sheet describing the board parts once a while back. I'll have to look that up.
Donny