Hey guys, I’ve been trying to get my bluetooth module working with my ARC-32.
The module is an RN-42. I’ve tested it by connecting the TX and RX pins together; with echo turned on, I get repeated characters of what I type.
On the ARC-32, I did the same thing. It also works.
However, when I mix the rx and tx lines between both serial interfaces, I get nothing on either side.(I have tried flipping rx and tx for one of the sides just as an idiot test, and it didn’t do any better)
The devices both communicate with themselves fine, but not with each other. What am I doing wrong?
The baud rates are both 9600 as far as I can tell.
I checked out your website. There is very little technical information there. In order for us to be able to help you we will need to see images of your wiring, and power supplies.
Ah yes, I’ve started a new version which will hopefully remedy the issues with the last one.
I want bluetooth connectivity so I can try and do some cool more higher level control from my computer eventually. As I’m waiting for parts, I though I’d just try and actually connect the bluetooth module to the ARC32.
here is the main image with the RX and TX pins in question: i.imgur.com/BXTwi.jpg
(I didn’t use the image tag because I failed at resizing the images and it is way too huge)
Pin 1 is Tx on the RN-42
Pin 2 is Rx on the RN-42(I know I labeled it incorrectly on the actual device :p)
It works just as expected with the loopback test:
I have a computer connected to the module, and through PuTTY connected to COM4 I get back what I type whenever pins 1 and 2 are connected.
The same goes for 3 and 4.(These are connected to the [now removed] jumper positions for the FTDI chip on the ARC32, basically completely circumventing everything and just being serial pins to COM3 in the computer). I connect PuTTY to COM3, and I get back what I type whenever pins 3 and 4 are connected.
However, when I attempt to mix the two sets, I get nothing at all.
I believe I’ve tried every wiring combination (there are only 2) in addition to only trying 1 wire at a time(for which there are 4 possibilities).
I can never get input from COM3 to appear in the window for COM4 or the other way around.
Both PuTTY windows are set to a 9600 baud rate.
What am I missing?
As I typed that I believe I may have thought of my error…
The RN-42 chip operates at 3.3v, the ARC32 operates at 5v…
Is this the issue, and, if so, is there an easy way to rectify this…?
Thanks
I don’t have any input on the level shifting. I’m suspicious of the connection of a voltage regulator using a servo extender. Not sure of the part used but there needs to be capacitors connected as well. Not saying this is causing your problems, but I wanted to point out a source for potential issues.
The level shifting is definitely a problem. You’re going to either need to get a level shifting ic chip or build your own circuit. Sparkfun makes a lot of easy to use shifting boards. Here’s a cheap one that would do the job sparkfun.com/products/8745
EDIT: I forgot to mention that with any shifting circuit you’re still going to need to provide the 3.3v source. You’ll need to hook a vreg to do this.
I have never tried to hook up something to an ARC32 to replace the USB connection, Also I do not have any of the Rev3 Arc32 boards so can not help much there…e
However my quick look at the latest Arc32 data sheet, it appears to me like you are trying to hook up the BT module to the FTDI input/output pins of the ARC32, instead of the actual input/output pins that go to the RX/TX pins of the Arc32… Is this intentional? ie you are then trying to use the FTDI to talk back to your PC with the data from the BT? If not you may want to move your connection to the pins closer to the outside of the board…
Also do you have a test program your are trying this out with? If so you might want to post it…
Not sure of the part used but there needs to be capacitors connected as well. Not saying this is causing your problems, but I wanted to point out a source for potential issues.