I am working on my first project with Arduino.
When (and if ) it will work, I shall post purpose, description, schematics, code and pictures on the forum.
The project involves a 16x2 display; Arduino, display and other components are on a prototyping board wired on the back.
As usually, I split the project and tray and attack problems one at a time. I started by checking the working of display and disconnected all non relevant connections.
Wiring and code are per the exemple “Hello world”.
Only wiring difference: In a thread - before posting I searched the forum trying to solve the problem myself - Paul__B suggests a different use of contrast potentiometer.
Tried with several resistance value between display PIN 3 and GROUND: the optimum is about 3k: character rectangles just appearing.
But no displaying of code programmed characters.
NOTE: In my Arduino Uno there is a failure:
With power supplied by computer USB:
Voltage on 5V pin is 5.2 Volts – I think correct.
Arduino works properly with exemple code “Blink” - no wiring involved.
With power supplied at 9 Volts by plug:
Voltage on 5V pin is 7.5 Volts and varies if 9V input voltage is varied.
Very likely I unknowingly damaged the internal 5V supply.
The above contrast tests were made with USB power supply.
My question is: Can the missing displaying be related to this damage?
Can you guys suggest other tests to do?
I am afraid I shall anyway acquire a new Arduino.
More questions will surely arise when I shall test other parts of the project, but one step at a time.
I hope to have been sufficiently clear and thank in advance for any comment and suggestion.
Sounds like you fried the regulator.
Where did you put the 9v supply.....on the raw terminal is required
A 5 K pot I believe is connected with one outer pin to ground and the centre connection to your display pin 3, that's it
#TomGeorge: the 9V supply is from a DC-DC converter based on XL6009 . Output voltage largely adjustable. It is in turn supplied by a 6V lead-acid battery.
Attached the features. Model number (and plate if any) is presently concealed under PC board.
#jremington: it's what I expect. I don't repent for havig made a mistake, it would not be the first neither the second. What worries me is that I did not notice when and how I fried the regulator plus something else. Thus I am liable of doing it again.
I wonder if someone could repair the Arduino, perhaps replacing the regulator chip. And then other components can likely be damaged. But I would give a fortune for knowing how it happened.
With a hot air rework station and some practice, it is not hard to replace the chips on an Arduino board. But it is quicker and easier to buy a new one ($2 for a Pro Mini clone on eBay).
Sandro36: #bluejets: 9V is input through the barrel jack.
#TomGeorge: the 9V supply is from a DC-DC converter based on XL6009 . Output voltage largely adjustable. It is in turn supplied by a 6V lead-acid battery.
Attached the features. Model number (and plate if any) is presently concealed under PC board.
#jremington: it's what I expect. I don't repent for havig made a mistake, it would not be the first neither the second. What worries me is that I did not notice when and how I fried the regulator plus something else. Thus I am liable of doing it again.
I wonder if someone could repair the Arduino, perhaps replacing the regulator chip. And then other components can likely be damaged. But I would give a fortune for knowing how it happened.
Thanks to all for assisting.
Carefully read the replies such as I supplied and give answers accordingly if you hope to learn from your mistakes.
Your saying the 9v is a barrel jack means nothing.
#bluejet: <Where did you put the 9v supply.....on the raw terminal is required>
Perhaps I misunderstood your question (language problem?). I should have asked for explanations.
Please, what did you mean exactly?
#bluejet: <Your saying the 9v is a barrel jack means nothing.>
With <9V is input through the barrel jack.> I just meant that Arduino is fed at 9 Volt via the jack plug (language problem again?).
#jackthom41: I could have used, with less fuss, the 6V from the battery but I read that Arduino Uno, when not connected by USB, must be supplied by an external power supply at a voltage between 7 and 12 Volt (Book “L’ABC di Arduino” by Futura Group Edizioni, in Italian. ISBN: 9788890952913). I choosed 9V.
If this information is incorrect please tell. I should be grateful and change my designs accordingly.
Sandro36: #jackthom41: I could have used, with less fuss, the 6V from the battery but I read that Arduino Uno, when not connected by USB, must be supplied by an external power supply at a voltage between 7 and 12 Volt (Book “L’ABC di Arduino” by Futura Group Edizioni, in Italian. ISBN: 9788890952913). I chose 9V.
If this information is incorrect please tell. I should be grateful and change my designs accordingly.
That information - published many years ago by the Arduino project and as you see, embedded in various "helpful" books and "tutorials" - is complete nonsense!
The regulator on the Arduino UNO/ Nano/ Pro Mini/ Mega2560/ Leonardo/ Pro Micro has very little heatsink, so will not pass very much current (depending on the input voltage and thus, how much voltage it has to drop) before it overheats and (hopefully reversibly) shuts down. It is essentially a novelty provided in the very beginning of the Arduino project when "9V" power packs were common and this was a practical way to power a lone Arduino board for initial demonstration purposes. And even then it was limited because an unloaded 9 V transformer-rectifier-capacitor supply would generally provide over 12 V which the regulator could barely handle.
Nowadays, 5 V regulated switchmode packs are arguably the most readily available in the form of "Phone chargers" and switchmode "buck" regulators are cheap on eBay so these can be fed into the USB connector or 5 V pin to provide adequate power for most applications. Unfortunately, many tutorials or "instructables" are seriously outdated or misleading and have not been updated to reflect the contemporary situation.
If powering from batteries, as long as the battery pack cannot exceed 5.5 V, this must be connected to the 5 V pin. In your case, a 6V lead-acid battery is a little bit tricky, you really need an efficient switchmode "buck-boost" regulator or probably just a low-drop-out ("LDO") series regulator as it would actually waste less power than trying to convert the voltage twice. But it needs to be rated and heat-sinked for as much current as you will be drawing as the on-board regulator is most likely not. Best thing to do if you think it is damaged, is remove it - permanently!
I am surprised if 3k is the right value for your contrast pot, though if your 5 V supply is high, it may be. You will need to actually display data before you can get the right value.
I searched with “Arduino Uno power supply”.
The first three sites I found are theese:
-No source provided:
What power supply do I need for Arduino Uno?
The board can operate on an external supply of 6 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may be unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts
I wonder how many new users of Arduino have fallen in my mistake.
I think it would be very important that this general error broadcasting would be stopped. Perhaps a thread by moderators could be posted and kept on top of all threads, stating the correct way of power supplying Arduino boards.
I just remembered an old thread in February.
In it Wawa clearly said that 6V were not enough and suggested to supply more than 7V.
Whom shall I trust? I don't yet know Forumites enough,
I expect the coming in of a reputable/expert Arduino man who would positively settle the argument.
Meantime I'll follow Paul__B's suggestion.
