Last night was a fun night.
I went to sleep after I made my simple project work.
The mission was to activate a relay based on the values from a light sensor.
The problem was that I didn't realize that the relay was a 12V one so it took me a while to understand I need to input 12V to the UNO and pass it via vin output to the relay while using the 5v output for the light sensor.
Long story short, after hooking the 12V input everything worked.
I woke up today and wanted to update the logic but saw that the UNO usb serial was not detected by the IDE (Mac).
Tried other USB ports but non worked.
The "funny" thing is that the program still works, I see that the relay responds to the amount of light but the usb serial is missing from the IDE.
Your board will not be shown in the IDE if the operating system does not recognise it. I'm not a Mac user can't advise how to figure the OS side of things out.
Possibly not relevant at this stage but what version of the IDE are you using.
Was it a relay or a relay board? If it was a relay, how was it connected? Please post the specs / url of the component(s).
As asked earlier, please provide a schematic (photo of hand-drawn one is fine); make sure all connections including power and GND are on it.
What is the TTL-to-USB converter on your board? For an original Arduino and some clones, it will be the 16U2, for most other clones it will be the CH340.
That would indicate that the TTL-to-USB converter is damaged or has died.
Vin can happily be used as output; you will loose a diode voltage drop. Relevant part of the schematic
Actually I didn't fully understand if something in my schema is wrong.
I can buy another UNO but if I wired something wrong I would like to know so I don't repeat the same mistake again.
I drew by hand the schema (hope it's better than the previous image )
The thing is that it worked but after connecting the 12V input into the UNO all of a sudden the USB communication does not work although it looks like the Arduino functions regularly I just can't upload anything to it.
I know I might be repeating myself, just wanted to double check I explained myself well...
@ua6em@jim-p sorry for the late reply, I was away for a while.
If you check this link you'll see that vin can also output voltage that you input via the barrel jack.
So basically, if I understand correctly, there was nothing wrong with my schema but still something went wrong and I can't connect to the Arduino board via the usb cable.
