Comments on: RFM12 Tutorial – Part2

By: chippchipp

chippchipp — Sun, 18 Dec 2011 11:07:23 +0000

hi,
The last time I contacted you was Dec 2010.
Now have my project working fully and I think I understand about 55% of the workings of the RFM12b.
The two modules communicate 100% no problems.
One thing I have notice.
I replaced my original Rfm 12b modules with two new rfm12b which I purchased in july 2011.
After power up i found problems with the first second and maybe third communication data packet occurs now and then but after say the fourth data packet the two modules will communicate continuously, not missing any data thereafter until I power off and power up or I move one of the modules out and then back in range.
I reverse fitted the new modules (swapped them round on my embedded application) and guess what.
I modules communicated perfectly from power up??
Have you seen this or have any ideas to what to change to debug or tune this out.
The two modules are embedded on exactly the same pcbs..
Just one module acts as the master and the other the slave.
I have increased the preambles.No change
Are there any parameters which you could point me to look at

Thanks
Chippchipp

By: Stephen Eaton

Stephen Eaton — Wed, 28 Sep 2011 01:43:51 +0000

@Amir I’ve not used the non-fifo mode but it appears in the documentation that you need to set ef=0 and use pin 7 to get access to the incoming data for Rx and for Tx you need to use pin 6 to send your data.

By: Amir

Amir — Tue, 27 Sep 2011 14:20:05 +0000

hi
how can I used Rfm12 In No fifo mode?
Iwant read data direct. no in fifo register

By: Scurvyrat — Reading the ARSSI pin on the Si4221/HopeRF 12B

Scurvyrat — Reading the ARSSI pin on the Si4221/HopeRF 12B — Tue, 14 Jun 2011 21:52:03 +0000

[...] has been a bunch written about this signal. You can read about it here (German, with photo), here and here. There is work to translate this signal to an OOK [...]

By: ulf_l

ulf_l — Thu, 30 Dec 2010 10:42:48 +0000

Hello

You wrote “nFFS – If pulled high then the FIFO is selected”. As I understood the datasheet the pin must be pulled low to select the FIFO.

Ulf

By: Stephen Eaton

Stephen Eaton — Fri, 10 Dec 2010 01:55:39 +0000

@chippchipp

Yes I can certainly appreciate what rfm12 newbies go through. the biggest problems is what comes first the chicken or the egg, e.g. is the problem in the Tx, or is it in the Rx side of things.

I certainly agree with you. I could not have got my original design working without an oscilloscope watching the CLK and the MOSI/MISO however this was a pain as I only have a two channel CRO, I’ve since treated myself to a logic analyser that can decode SPI and find this invaluable when I troubleshoot.

When I get around to finishing off the tutorials I’ll look at putting some timing diagrams on.

stephen…

By: chippchipp

chippchipp — Tue, 07 Dec 2010 14:49:04 +0000

Hi Stephen
I have been researching and developting an application using the RFM12B.The data on this module is not good,
What i have noticed is a Digital signal analyzer or scope is required becasue of the lacking data sheets as to correct program flow.
What would be a good start is if an experience rfm developer(yourself) could provide timing diagrams showing the state of lines
NSEL,SCK,SDI,SDO,nIRQ, and VDI in relationship to el,et,synthersizer/pa etc,etc when running a sample program.
Now i am using a scope things are becoming much easier to grasp
Chippchipp

By: realheaven

realheaven — Mon, 04 Oct 2010 16:14:33 +0000

@ geo 116

you may choose RFM12 instead of RFM12B because RFM12 can run well at 5V so there’s only one power supply for the two devices and to manipulate those RF is the same.

By: RFM12 Tutorial – Part1

RFM12 Tutorial – Part1 — Mon, 26 Jul 2010 14:00:04 +0000

[...] Next – Part 2 [...]

By: Stephen Eaton

Stephen Eaton — Thu, 22 Jul 2010 03:25:26 +0000

@geo

The RFM12B has 5V tolerant I/O, however in saying that I wouldn’t leave it running at 5V for an application as it may shorten it’s life. When I first started development I didn’t use shifters etc and all ran ok.