This is one of those worked for months and now does not work problems. I have been using 5vdc/1A and 5vdc/2A phone charger to run an UNO with an ether net shield for at least a year. I just moved the project into a plastic box. Now none of the 6 different phone chargers and one apple fire pad charger I have tired will work.
This is the second odd thing, it works fine when plugged into the USB on a PC.
With the chargers a few of the lights on the ether net shield flash and then a red and green one stay lit. That is about it unless I plug it into a PC. I tried switching wall sockets. It will just not work with a charger anymore. Any idea what could have changed and why the difference between a PC and the various USB chargers?
Quick update: I checked the voltage on 2 of the USB chargers and one was 2.45vdc the other 3.7vdc.
The PC USB was 5.07vdc.
For what ever reason all of my chargers seem to be regulating low even though they had worked previously. So low voltage seems to be the problem.
I did read one web post that says adding a 1000uf capacitor will help with the USB charger regulation. I will try that. It is very strange that all of a sudden all of the regulators stopped regulating properly with the UNO. The UNO hook up is very simple I have a photoresistor connected between ground and pin 2 (INPUT_PULLUP) on the the UNO. When light hits the photoresistor the UNO runs a program.
About to give up. I stripped down a USB cable so I could hook my DVM instead of sticking the probes into a USB plug. More confusing information. I have a pocket juice battery backup for a cell phone. It was partially use but its charges lights says it was close to fully charged. I connected it to the UNO and the UNO did not power up. When I checked the voltage from the Juice it read ~3vdc by accessing the USB directly with the DVM? I used a different fully charged battery back up and the UNO worked. I measured the fully charged battery back up and it was 5.11vdc. Well that sees to check out. Now the strangeness begins again. I plugged my cut USB cable into the USB charger and I measured 5.07vdc??? I then plugged it into the UNO and it worked??? Well I guess it should have because for some strange reason it was not putting out the proper amount of voltage??? I am going to post another question to see if anyone what could be happening with USB chargers to cause this consistent reaction to what seems like the power line?
You are allowed to use line spacing to make things a little easier to read.
Looking at you last post It would appear that you were trying to supply the USB port with less voltage than it expects.
This in and of itself could cause various issues ranging from intermittent uploads to erroneous readings from external sensors to the board simply not working.
The board expects a reasonably consistent supply voltage from the USB port for the circuitry to work properly.
Such large variations (although you might consider them large) will give issues.