Hi,
This is my first post to the forum, and I hope my questions haven't been asked before.
I am trying to port the RFM69 library to run on the ESP8266 module, which I think makes a great module for acting as a gateway between RFM69 based sensors and wifi
Simply changing RF69_SPI_CS, RF69_IRQ_PIN and RF69_IRQ_NUM to match the wiring of the ESP8266 seems to work. I have a RFM69CW module connected to an ESP-12, powered through an AMS1117 regulator. I have a 470 uF capacitor on the output of the regulator, and 100 nF between VCC and GND on both the ESP and the radio module. Reset is connected to GND though 100nF (as in the RFM69 datasheet) and finally a 4.7uF across VCC/GND on the RFM69 (suggested in the MySensors forum). Both modules are mounted in sockets on a prototype board and everything is soldered together, with as short wires as possible (no breadboard)
I have the Node sketch (from RFM69 examples directory) on the ESP8266, with the SPIflash and Blink code disabled, and the Gateway sketch on an Arduino Pro Mini. Using the latest RFM69 library from github. ATC is turned off. I monitor the 868 MHz spectrum using a HackRF One as a spectrum analyzer (with Cubic SDR). When I turn on the ESP it transmits, and retries 3 times, as expected with sendWithRetry(). Nothing is received on the Arduino side. If I touch the antenne on the ESP8266 it works! The Arduino receives that data, and the ack gets back to the ESP8266! RSSI values looks fine (-30 to -26). Currently using 82 mm of wire as an antenna. I tried to solder an SMA connecter to the module and use a rubber antenna - same behavior
When I look at the waterfall in my SDR receiver, I notice that when thing's are not working, the transmit from the RFM69 takes up approx 6 MHz of spectrum, and while I touch the antenne, it's approx 2 MHz (The two radios and the HackRF are all three within 50 cm of each other). I have very little experience with high-frequency circuits and have no idea how to debug this (except for keep on adding small capacitors at random places on the PCB!). Even the 2 MHz bandwidth seems like a lot to me. A nearby baby monitor uses much less spectrum, and that's also what I would suspect from the RFM69
Any ideas on how to stabilize the setup is greatly appreciated
- Jan