1) Wiring or schematic and/or code?
2) Are you using a Moteino or RFM69 library?
3) What antenna do you use?
4) What's the motion sensor and how does it work / packet structure / details ?
1) I have basically just hooked up the SPI lines from the RFM69 module to an Arduino Pro Mini 3.3V (for control), and have attached my logic analyzer to the
DIO2 and
GND pins on the module (for reading the raw data). My SPI hookups are the same as in
this guide. I can post a schematic or upload a picture when I get home if preferred, but it is a very straight forward hookup.
My
code right now just constantly prints the RSSI value. Around -95dBm when idle, -40dBm when a sensor is transmitting.
What's probably more useful is the
RFM69 library configuration data. Mind you, I've tweaked about every parameter I could in attempts to eliminate the random noise. Having tried about every permutation I could think of for the config values, I may have mucked up the config a bit. This is just the last version I tried, after deciding to remove anything that seemed irrelevant to continuous mode (i.e. all packet/sync configs). It does the same even with all default values. I've changed bit rate, frequency deviation, RSSI threshold, I've tried turning off AGC, messing with RXBW, etc., but I always get noise (except when the sensor is actual transmitting...which makes me think its some automatic gain thing?). Bit rate should technically be 20Kbps but that should only matter when I go to actually parse the data, not when just trying to eliminate noise I expect?
2) I am using
this board (915Mhz RFM69) with the RFM69 library.
3) Initially I used a 78mm length of wire, and in attempts to reduce the noise I desoldered the actual antenna from a receiver unit I had and put it on the RFM69 board, but saw no appreciable difference.
4) The motion sensor is a Guardline Driveway Sensor. You can see specifics
here. It is a very simple protocol, basically transmits a 24bit ID repeatedly 30 or so times. I've already successfully read this ID by grabbing the data from the
DATA_OUT pin on the
Amiccom A7201B chip the receiver units use to read the transmission, now I am trying to do away with the receiver unit entirely by using my own receiver module. Since I cannot source A7201B chips I decided to try this RFM69 module first.
The data is sent at frequency 914.8MHz @ 20Kbps using FSK modulation.
I had assumed this module would be able to demodulate the signal and pass me the raw data with low noise so my MCU could parse the signal. Perhaps there is another module that would be better suited for what I am trying to do? Or if this module should be able to handle it fine, maybe there is some setting I have not configured properly.