@gohan said in nRF24 would not transmit when connected to Nano, but works fine with Mega:
voltage regulators usually can not keep up
LP2985 on Mega gives 150mA, which is at least in double excess of the highest nRF24 +LNA+PA can consume. It should do fine without the cap.
On Nano it is not a voltage regulator. FTDI chip converts serial to USB. And for Nano I did use the caps 4, 10 and 20 uF - none helped. Honestly, I haven't noticed any effect of these caps so many on the forum talk about. If it works, it works, if not - bad luck. I can believe in a very rare case the extra charge of a 20uF cap could topple the scale, giving illusion that this is a solution.
When I reduced from RF24_PA_MAX to RF24_PA_HIGH it started to work sometimes. When down to RF24_PA_LOW it works stable. However I transmit 7 bytes only, the payload can be up to 32 bytes. This will further increase power requirements and will further short 3V3 output.
In order to save MySensors lib from ungrounded suspicions (which I had) and simply to act professionally we should admit that on Nano the 3V3 output should not be used. Otherwise the behavior is undefined. Even without PA. The spec for nRF24 says 14mA at transmission. The spec for FTDI says it 15mA typical, 24mA max. It is an unacceptable low margin for expecting stable communication.
