I am using this shield kit here:
I don't have it set up as a shield, just wired to the board via the 5v, GND, and the 2 analogue pins. When I power the board with the USB the lcd lights up and works fine, when I power the arduino with 12v from the wall the LCD shows black boxes where the text would be and does not light up. I am sure this is a voltage issue or something of the like but not quite sure how to narrow it down. I have confirmed that my AC adapter is indeed outputting 12v.
Thank you!
I power the arduino with 12v from the wall the LCD shows black boxes where the text would be and does not light up. I am sure this is a voltage issue or something of the like but not quite sure how to narrow it down. I have confirmed that my AC adapter is indeed outputting 12
So where did you connect the +12V to ? ( 2.5mm arduino ext pwer jack ?)
Correct, I also tried using a step down¿? To bring it to 5volts 3A without any luck
Did you try readjusting the contrast when you powered it from the ext pwr dc jack ?
If you have a multimeter, check the voltage on the power pins of the shield using USB and then using the ext. dc pwr jack .
You can find the lcd power pins using this diagram
Finally got a chance to do some tests. When plugged in with the USB my arduino Uno's 5volt pin reads just under 5volts when plugged in using the buck converter from adafruit I get about 3-4volts from it. Any ideas on how to compensate for this?
Buck Converter
To add to the confusion volt pin on my arduino supplies the correct voltage when powered by both the buck converter as well as the USB
That's not enough info. We need to know what voltage you set the buck converter output to and whst voltage is on the VIn
pin on the arduino. Also whst is the input voltage of the converter.
Converter in: 12v
Buck Converter Out: 5.4v
Vin Pin when powered by buck converter: 4.9v
Vin when powered by USB 4.4v
I expect there to be a bit of variation in these because my tester while not total crap, isnt exactly a work of art either.
I don't think you understand . "Vin " in the INPUT to the 5V REGULATOR
IT NEEDS TO BE 2 to 2.5V HIGHER THAN THE OUTPUT (5V) so that means the MINIMUM Vin is 7V to 7.5V.
The Vout (that' Vcc to you which is labeled "5V" on the board (not Vcc) should be about 5.1V dc
Adjust the pot on the buck converter up just slightly until the voltage on "Vin" is 7V. Make sure the buck converter is actually connected to "Vin " and not "5V" . Presumably you have a 2.5mm round plug plugged into the external dc power barrel jack.
If you don't have the plug , Vin is the same thing.
Your USB voltage is too low because you exceeded the 500mA maximum load for the USB. You have over-loaded it. Disconnect the buck converter , plug in the USB with the voltmeter connected to "5V" pin and start disconnect things , starting with the lcd shield
(with the power off of course) . Disconnect your loads , one by one and then plug in the USB and measure the 5V pin again. You will see the voltage increase , the more load you remove. It's not rocket science.
OK, so I read through your post a few times and you are correct I was misunderstanding. It seems I have been making several mistakes, all the numbers I posted were the board on its own, nothing plugged into it (no LCD or other forms of resistance) Where I was making a mistake is in my understanding of the Vin pin and its purpose. I had the 12v source connected to the buck converter which was connected into another barrel cord plugging into the arduino via the female barrel power port on the arduino, not the Vin as I should have. The second mistake I was making is in the voltage of the buck converter, all by itself the output reads just over 5v which is what I expected based on adafruits description. I understand that I will need more than this coming into the arduino to power the LCD but I am not quite sure how or if I can alter the buck converter to supply this. Thank you for your help so far, I really appreciate it
You don't have to change it. I didn't look at your link until now.
Just connect the 5V from the buck converter DIRECTLY to the 5V pin of the arduino with NOTHING plugged into the barrel jack
and with NO USB connected. This will work. You cannot use the barrel jack with that buck converter.
If you had bought this one , you could adjust it:
http://www.miniinthebox.com/lm2596s-power-module-lm2596-dc-to-dc-buck-converter_p1113808.html?currency=USD&litb_from=paid_adwords_shopping&gclid=CjgKEAjwzIucBRDzjIz9qMOB3TASJABBIwL11WdjYbLCV25sDoT4wpcoHVyCzutB9oH-vop-aqFoavD_BwE
Ah, I see what you mean, I joined the power for the arduino and the LCD together then fed that directly into the 5v pin and the arduino powers on fine but the LCD now shows 4 solid blocks and adjusting the contrast doesn't help only makes them disappear entirely with no backlight.
I feel like I am making a stupid error, I have the wires from the buck converter joined with those that power the lcd then running directly into the pin on the arduino, I read the voltage at that junction at just over 5 but still no luck with the LCD
Update: just tried powering with the USB and got the same result.