My Arduino UNO is up and running, but no mqtt messages


I don’t have anything connected to my Arduino UNO apart from recover and transmitter.
I built the project a month ago so don’t have the results, but there’s nothing wrong with it.
From memory, it was unstable when I went down to 128 so I decided to stick with 256…


Are you now connected to D3 or D2? (nothing to RX)


It’s all as per Wiki - pins 3 and 4.


If you plug the usb cable at start could you post what OMG shows on serial monitor?


Well, I normally power up my Arduino via the round power connector.
When I disconnect it from mains power adapter and connect to my PC with a USB cable, it starts just fine, here is the opuput in Serial Monitor:
Simple ethernet config
OpenMQTTGateway ip:
Ethernet ok
Connecting to MQTT by IP adress
ZgatewayRF setup done
Setup OpenMQTTGateway end
MQTT connection…
Connected to broker
Subscription OK to the subjects

I tried to power it up via USB cable (using a 5V phone charger with a USB socket), but it doesn’t make any difference to the original situation - it hangs until I press reset button on it.

I suspect that Arduino receives something via USB that makes it boot when connected to PC.
Any idea how to overcome it?


What is the measured voltage on this plug?


It’s 9V. (stupid min 20 characters rule)


Could you post a photo of your setup (not with usb but the board wired with the power connector)?


there is no difference to this picture, I just plug a power adapter into the slot.
And as I said, it works the same if I power it up via USB port.


It seems that you have data connected to TX on this picture and not to D3 as it should




Did you try with some basic blink sketch if you have the same behaviour (also with w5100 connected)?


No I didn’t.
What should I upload?
I presume it needs some basic configuration as well?


Not, just upload a basic blink example provided with the ide, add the w5100, connect a led with a resistor and see if you reproduce the same behaviour


Any instructions on what pins to connect a led to?