NRF24 problems with cold temperatures
Has anyone else had problems with cold temperatures and NFR24 chip? I have used Arduino Nanos and Pro Minis with normal ebay NRF24 chips with/without capacitors and also with the standard attach board which has 5V input etc. Power supply has always been an adapter ("Hlk-Pm01 Ac-Dc 220V To 5V" or just mobile phone power adapter) so there should be no power issues. Have been feeding also power directly to the NFR24 bypassing Arduino's limitations etc. So far it seems that somewhere near 0°C the nodes stop responding. When bringing back inside, they revive and continue working. Arduino blinks and seems to do something, but communication just freezes (need to do more investigation how Arduino itself is affected). It's worth to mention that my Wemos D1 Mini nodes have been working perfectly in same conditions (same power adapters, locations, -20°C). Radio coverage shouldn't be an issue as there are already couple of inside repeater nodes near the outside locations.
I have just oredered couple of sensebender boards for monitoring fridge/freezer temperatures and because they need to be battery operated + facing cold temperatures I'm starting to wonder if they will work at all. I have tested this with several NRF24 chips form different orders so it shouldn't be faulty batch related issue.
@Sushukka atmega328 and nrf24l01+ are rated for temperatures down to -40C so they should be ok.
I think you can define MY_DEBUG_VERBOSE_RF24 to log more detailed information about the communication between the mcu and the nrf.
From what you wrote it should like you are powering the nrf directly from the hlk with 5V. Is that the case or did I misinterpret what you wrote?
@Sushukka - I had one node with the same behaviour when we had -15 dgr here in Sweden. I took it inside and it worked, tried to put it back outside and same behavoiur. I changed the electrolytic capacitor on the radio and then the node has been working since. I also found a dead spider which most likely wanted to steal some warmth.
Same to me. Nodes didn't work below 0°C.
I changed the capacitor at the radio to a new one w/ bigger value (47uF). Now it works...
Some nodes got a tantal cap (10uF) instead, which works good too.
Have been powering nrf directly from power adapter using the the 8pin socket adapter boards which have internal 5V->3.3V converter. Have been using nrfs directly with Arduino too. Sundberg84 do you mean the "Decoupling-Capacitor" connected directly to VCC+GND pins on the radio (https://www.mysensors.org/build/connect_radio) or something else already on the board? With my latest node I used 47uF/16V electrolytic capacitor soldered directly to the VCC/GND pins. Last reading from the node's temperature sensor was -3.2°C and then nothing.
@Sushukka yes you need to replace the capacitor connected to vcc/gnd on the radio. When temperature is too low the electrolyte inside can start to freeze... Try higher value (but not sure it's a great solution), or instead a better capacitor technology for sensors that are outside: either tantalum or ceramic.
Thanks Nca78. I ordered some 47uF/16V tantalum capacitators. Hopefully they will work. Ceramic would have been better but they seem to be only available on a very small (pF/nF) level.
Update: Managed to get my NFR24 radios work with Sensebender micro with greatly oversized 100uF normal electrolytic capacitor. Been in my freezer (appr. -20C) now for three days and still works fine. 2xAA batteries powering the node. Not sure where the problem is, maybe just the capacitor size because of diminishing capacitance curve in freezing temperatures. Have still some spare Nanos and Pros to spend, but gradually moving to ESP8266 based sensor network. They have proven to be very reliable even under -20 degrees celsius.