RF12Demo Help Needed! « Jee Labs Talk

Jee Labs Talk » How can I fix ... ?

RF12Demo Help Needed!

(4 posts) (3 voices)

Tags:

No tags yet.

tearabite
Member

Hi, I am having trouble getting my RFM12B modules working with the library. I am unsure whether the issue lies with an incorrect connection RFM12B -> Arduino or of I am using the code improperly.

When I load up the serial monitor, the help text displays. But any input is entirely ignored.

I have traced the problem down to a particular function call railing the uC. rf12_xfer() (specifically the calls in rf12_initialize()) are calling rf12_xfer(), but then rf12_xfer() goes into an infinite loop.

Is this an error that can be caused by improperly connecting the modules to the arduino?

Currently I have:
RFM12B connected to Arduino
------------------------------------------
nIRQ --> 2
SCK --> 10
SDI --> 11
SDO --> 12
SCK --> 13

That configuration was determined using the eagle diagram on the site in conjunction with the pin definitions in the RF12.h header file.

I am using these modules for a school project and would greatly appreciate any insight into this error.

Thanks so much!!!!

Posted 4 months ago #
gotcha
Member

Hi tearabite, on a Jnode the wiring is:

nIRQ --> PD2
SEL --> PB2
SDI --> PB3
SDO --> PB4
SCK --> PB5

And in the Duemillanove, you have:

PD2 --> I/O Port 2 (OK)
PB2 --> I/O Port 10 (OK)
PB3 --> I/O Port 11 (OK)
PB4 --> I/O Port 12 (OK)
PB5 --> I/O Port 13 (OK)

So it seems OK. Did you check Vcc? RFM12B maximum rating is 3.8V.

Here is a link you might like to check: http://talk.jeelabs.net/topic/71

Posted 4 months ago #
tearabite
Member

Thanks for the reply! I have Vcc connected to a regulated 3.3V source and GND of course connected to ground. All other pins on the RFM12B are left floating.

After tracing the crash further, I have found that it is possibly spi_initialize() that hangs. The first run through rf12_config() executes no problem. The second time through, the program hangs at spi_initialize() inside rf12_initialize().

I know the 168 has a 16MHz clock, so I even went as far as to remove the code in spi_initialize() that checks the clock speed to determine the correct divider for the SPI clock to no avail.

I am trying to trace where the problem is coming from, but am getting nowhere.

I am totally unfamiliar with hardware SPI especially on the arduino boards.

In the demo program, rf12_config() is executed twice. Once before the showHelpText() and once after. It is the call AFTER the showHelpText() call that hangs. It may benefit me to know what changes between those two calls?

Thanks again for your help!

For the record, I am using an Arduino Diecimila with an ATMega168.

Posted 4 months ago #
Jean-Claude
Key Master

It may not be enough to connect just VCC to 3.3V, all the I/O pins of an Arduino are also 5V levels, which can cause problems when connected directly to the RFM12B. One way to get around this is via some resistors - see an older post at http://news.jeelabs.org/2009/01/13/arduino-rfm12b-µsd/

Posted 4 months ago #

RSS feed for this topic

Reply

You must log in to post.