Hi all, I'm running into an issue with programming my Nano clone and getting it to recognize in the IDE. If the Nano isn't in the circuit (read: just a bare Nano with nothing attached), I can upload sketches fine. Then when I put the Nano back into the circuit, the sketch runs. However if I plug in the USB cable while the Nano is in the circuit, it isn't detected by either the IDE or Windows Device Manager and the onboard power LED is very dim. Attached is my circuit.
Here are some additional details:
The external power source is a 12v to 5v buck converter. Either USB is plugged in, or the buck converter to 12v, but never both. The Nano is taking only one 5v source at a time (USB or 5v pin). When the Nano is in the project, the buck converter is attached to the 5v pin, but with the 12v end disconnected.
The resister I have attached to D2 is 470 ohm.
When trying to upload, the LED strip is not plugged in to avoid any excessive current draw over USB.
It is intended that I have five wires going nowhere in the bottom left of the picture. They are physically present in my circuit, but nothing is connected to them yet.
I wonder if the output of the buck converter is acting almost like a short circuit. If you have a multimeter you could check the voltage on the Nano's 5V pin when you are trying to power it on the breadboard from USB. Or you could try removing the red wire that goes between the buck converter and the breadboard to check whether the problem is due to the output of the buck converter taking a lot of current from the USB 5V when nothing is connected to the 12V input of the buck converter.
Posting an annotated schematic showing the points you measured the voltage and what you got. You have a picture with lots of nice colors but they do not convey the needed information. Also look on your buck converter and see if the input and output grounds are connected together. Also why not supply about 8 volts to Vin of the Nano, it will be a much cleaner power source to the processor. Post links to technical information on the hardware devices that show what voltage and current they need for example;
It is not clear where that red 5volt line from the buck converter is connected to.
It should only be connected to the 5volt pin.
Why did you draw wires on the TX/RX pins. Is there something else connected to them?
That could be needed with other boards, but not needed with a Nano v3.
You can safely leave the buck connected to the 5volt pin while uploading.
Leo..
This worked a treat. I thought I couldn't use two power inputs at the same time, but maybe that only applies to using the Vin pin? I've bricked a Nano before that way, I think.
It's okay to have USB connected and power applied to the Vin pin at the same time. I do this with a small project powered from a 9V battery at the Vin pin. I don't have to disconnect the battery when I want to upload or use the serial monitor.
I mashed this diagram together with screen snips from the official Nano schematic and added the blue lines and the black text.
When you have the buck output connected to the 5V pin and have the USB connected, D1 (5V auto select) doesn't conduct. So the 5V power to the Nano comes from the 5V pin. [Edit: The same reasoning applies to having power connected to Vin pin and USB connected]
It's not okay to have a power supply connected to the Vin pin, and another connected to the 5V pin at the same time.
