OK results of my hardware testing are:
When trying different chinese sourced NRF boards, the versions with PA+LNA use a LOT more power than boards without the PA+LNA features, really not surprising. What did surprise me was the chinese made LoLin nodemcu V3 board I am using can not power some of them at all. When trying to get them running the thing to look out for is the LED on the esp8266 sub board. If you press the reset button on the nodeMCU you will notice a small LED flashes. When you try and transmit this LED flashes about 6 seconds later showing the board has reset due to too much power getting drawn and the voltage sags low enough to cause a reset. Using capacitors did not solve this so my conclusion is the PCB traces on some (not all factories make them to the same quality level) nodemcu boards can not supply enough 5V power. I ruled out the USB cable and power supply as they power a PI2 without causing the rainbow icon that cheaper leads do. Raspberry Pis are very fussy on power so the test setup is very reliable.
The only one I could get running was the shielded metal cover version after first installing large capacitors on Vin and Vout and also running wire back further on the nodemcu board to grab power before it runs down the PCB traces. I now have reliable transmission to an entire house of globes from a single hub and can drop the packet_repeats down to a value of 8 which speeds things up. If my calcs are correct it now takes 23ms to transmit a state to a globe. So all 23 milight globes in my house are now changing in around 1 second all from the one hub, very cool.
Recommendations from what I found:
- Use a 5v power supply and feed 5v directly to the nodemcu (or other esp8266 board like D1 mini) PLUS send power directly to the nrf base PCB so the radios get good solid power directly and not through the nodemcu or D1 mini board.
- Solder on a 25uf solid tantulum cap (or any electrolytic between 25 to 100uf will also be fine just larger in size) on the Vout of the nrf base if using the base (see pic at bottom of this post) to connect your NRF boards with. The next post also shows where to solder directly to the nrf boards.
- Consider using better branded nodemcu boards from reputable suppliers as they may use thicker copper on the PCB making the previous steps un-necessary. I found the D1 mini gave more power as the tracks were shorter so if you can not solder I would use these as a base.
- NRF24L01 is one of the commonly faked IC’s. If you are paying less than $5 for the board the odds are it will be a fake IC. These IC’s do work but are known to draw a LOT more power than a genuine nrf24l01+ chip. All of my boards are pretty much going to be fakes as the printing on the IC is almost impossible to read. I ordered a number of the basic internal antenna boards from numerous chinese suppliers and some use a lot more power than other boards which appear to look the same. Adding capacitors did get them working so they were not faulty just power hungry from being a worse fake compared to the other better faked chips.
- If you do not need a 1km range then consider this board which I have not tried personally. It appears to not have PA+LNA features so will use less power and is more likely to have a genuine nrf IC. Both of these things will mean less power draw and will make connecting it directly to a nodemcu board much more likely to work first go without adding extra capacitors. Sadly there is no way to use it without soldering wires or header pins to the board. Cost is higher when you add the antenna to the board.
https://www.sparkfun.com/products/705 - Do not believe any chest beating claims of 1km or 2.5km ranges when choosing which board to use. See this link for what is commonly known as “the ugly fix”.
https://blog.blackoise.de/2016/02/fixing-your-cheap-nrf24l01-palna-module/
But why do that when ready made shielded boards already exist? Search for E01-ML01DP5 as they can be purchased for around $5 with the antenna included and this is the board I have settled to use. - The esp8266milighthub project defaults to using the full power of any extra on board amps. If you turn the power down which is now a feature in the hubs firmware it could/will reduce the power rail sag and improve comms. By turning down the transmit power you could very well get better range if you have not soldered on caps.
- Users on the web are reporting that separating the esp8266 from the nrf board with longer wires gives better results. My limited tests seem to confirm this as I have built some very compact units similar to the ones in the next post by @furax54 which do not perform as good as my prototype which has 4" (100mm) of push on style wires between the two boards.
The boards and the base I have tried are shown in this picture.
