Go Down

Topic: RN-41 bluetooth with an arduino (Read 2551 times) previous topic - next topic

SouthernAtHeart

Is there a tutorial or guide to using the RN-41 (http://www.sparkfun.com/products/8497)with an Uno or other arduino?
The RN-41 only costs $25 at Sparkfun, but the Bluetooth Mate Gold costs $65...  If is just a few components different and the knowhow to hook it up, I can supply the first, but the knowhow?  I've searched quite a bit, but there's just not much out there.  There must be more to it that I don't understand?

frank26080115

RN-41 are easy to use, there's no configuration involved. Just install the drivers, power it up, and it should let you pair with your computer without you actually doing anything to it. Then just wire it up to your Arduino's RX and TX and you are done.
Freelance engineer, consultant, contractor. Graduated from UW in 2013.

SouthernAtHeart

How do you wire it up?  Isn't it 3.3v, and the Uno 5v?  I thought you'd need at least a step up/down regulator.
Here's the schematic off the datasheet.  Could someone post a schematic of the minimum/simplest way to connect this to an Uno? 

frank26080115

Just copy the schematic of the Bluetooth Mate Gold if you need level conversion, or run the Arduino at 3.3V
Freelance engineer, consultant, contractor. Graduated from UW in 2013.

SouthernAtHeart

Trying to understand the schematic, and make the Rn41 work with the Uno.
  In the schematic I've attached from Sparkfun:
The part I've highlighted in BL:  Could that be replaced with the Logic Level Converter from SparkFun (http://www.sparkfun.com/products/8745)

The part highlighted in RD: Is that just a 3.3 volt power supply?  So the Uno has a 3.3 v pin, I could use, correct?

This is starting to all look pretty easy.

...what is the part I've highlight in GR? 

And lastly, There are 4 pins being connected, but I thought I'd just need Rx and Tx for a general purpose 'serial pipeline'?  Do I need rts & cts?

frank26080115

SJ is solder jumper

You don't need RTS or CTS

The 3.3V pin on the Uno can be used instead of a dedicated power supply circuit (I think... Only if RN-41 use less than 50 mA), but any version before Uno has a baaaad 3.3V supply from the FTDI chip and I would never use it.

You know what, I'm at work right now, but I have a way simpler way of doing level conversion than SparkFun. Level conversion can be done with a diode and a resistor, instead of the whole mosfet thing they have.

Code: [Select]


                           ^ 3.3V
                           |
                           |
                           >
                           > 10K resistor
                           >
                 diode     |
(Arduino's TX) -----|<|-----+---------- (RN-41's RX)

(Arduino's RX) ------------------------ (RN-41's TX)



use a high speed diode
Freelance engineer, consultant, contractor. Graduated from UW in 2013.

SouthernAtHeart

Thanks, to make sure I got the diode right, I drew up a quick schematic: 

Do I need to ground RTS or CTS? or just leave un connected?

frank26080115

Your diagram looks right

The diode should ideally have a low voltage drop, I forgot to mention that, get a Schottky diode

Leave RTS and CTS unconnected
Freelance engineer, consultant, contractor. Graduated from UW in 2013.

SouthernAtHeart

Thanks,
the 1N5819 is a Schottky diode, I thought?  I hope so, I've ordered some to use as motor pike shunts on my H bridge.

SouthernAtHeart

What do these numbers mean?  will the RN41 run off the Uno's 3.3 supply?

frank26080115

I actually don't know what the RX and TX supply current actually means, sorry.

The regulator that comes with USnooBie (see my signature below) is the TC1262 and can supply 500 mA worth of 3.3V
Freelance engineer, consultant, contractor. Graduated from UW in 2013.

SouthernAtHeart

Anyone else know if you can use the Uno's 3.3 v to power the Rn-41; the specs (see my previous post) kinda say 2 different things...

SouthernAtHeart


SJ is solder jumper

You don't need RTS or CTS

The 3.3V pin on the Uno can be used instead of a dedicated power supply circuit (I think... Only if RN-41 use less than 50 mA), but any version before Uno has a baaaad 3.3V supply from the FTDI chip and I would never use it.

You know what, I'm at work right now, but I have a way simpler way of doing level conversion than SparkFun. Level conversion can be done with a diode and a resistor, instead of the whole mosfet thing they have.

Code: [Select]


                            ^ 3.3V
                            |
                            |
                            >
                            > 10K resistor
                            >
                  diode     |
(Arduino's TX) -----|<|-----+---------- (RN-41's RX)

(Arduino's RX) ------------------------ (RN-41's TX)



use a high speed diode


Can I do a similar thing to use the 5V FTDI cable from sparkfun to upload sketch to a 3.3Volt pro mini?
Here's a schematic I drew up:

frank26080115


Can I do a similar thing to use the 5V FTDI cable from sparkfun to upload sketch to a 3.3Volt pro mini?


from http://www.sparkfun.com/products/9716

Quote
This board ship default to 5V, but you can cut the default trace and add a solder jumper if you need to switch to 3.3V.
Freelance engineer, consultant, contractor. Graduated from UW in 2013.

Go Up