I have been attempting to run a 16x4 liquid crystal display with both an Arduino UNO and I have also used a MEGA.. I loose power to the screen (flickering, etc) when attempting to animate 29 WS2811 LEDs. So my question is, would there be another way of doing this to make it work off the arduino power? I know I have a few other options, such as power the leds separate, use a dual voltage power adapter, etc.. but I am looking for another solution... I know that I can power 60 WS2811 LEDs with 1 Arduino Nano without any issues.. So the arduino by itself can power 2x as many LEDS.. but its just the LCD is taking power also.. I am running a 12v 1amp power supply to the arduino power jack.
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2\$\begingroup\$ Are you powering everything from the 5V regulator inside the arduino nano? Is it getting hot? \$\endgroup\$– svilchesCommented May 19, 2013 at 23:58
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\$\begingroup\$ Is this a LCD or an LED display? You mention both, and seem to use the two terms interchangeably too. Ideally, provide either images or a datasheet for the display you are working with. \$\endgroup\$– Connor WolfCommented May 20, 2013 at 4:13
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\$\begingroup\$ There is a possibility of it being an LCD display, with a multi-LED backlight. \$\endgroup\$– Anindo GhoshCommented May 20, 2013 at 5:56
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\$\begingroup\$ No, I am using a 16x4 LCD + a strip of WS2811 LED lights the arduino is unable to power both at the same time ... well I can light up the WS2811 with a solid color but the LCD behaves erratically when the LEDs are lit. \$\endgroup\$– jasonCommented May 20, 2013 at 8:39
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\$\begingroup\$ I am trying to power everything from 12v plugged into the power jack on the arduino \$\endgroup\$– jasonCommented May 20, 2013 at 8:39
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1 Answer
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The WS2811, in individual led mode, where each ws2811 controls only one RGB led, takes 18~20mA per channel. Three channels (RGB) times 18mA. Times 29 that you are using. That is 3 * 0.018 * 29 = 1.566 Amps at full draw (all leds full on, i.e. White). You are using a 12v input to the Arduino Nano's 5v Linear Regulator, a TI UA78M05CDCYRG3. It is a 500mA regulator.
In all cases, you are overloading both the 5v regulator, and the 1 Amp power supply, as well as wasting alot of that energy in heat. The reason that the LCD is flickering, is because while the WS2811 is fairly wide range and can deal with voltage droop (Voltage drop from high current draw), the LCD cannot. Anything lower than 4.8 or 4.9 volts, and you lose power to the LCD segment controllers, the contrast control, and possibly the backlight. The LCD takes hardly any current itself, but its backlight might need a few hundred mA.
Solution, use a switching regulator with the 12v 1A (12w) supply to get 5v 2A (10W) which will cover both the 29 leds at full 18~20mA and the LCD + Backlight + Arduino's power consumption.
Alternatively, use a bigger 12v 2.5A supply, a separate linear regulator able to handle 1.75A for the led strip.
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1\$\begingroup\$ Thanks for your answer... It didn't even occur to me that each of the 3 colors drew .018 amps... thanks for that... I ended up using a ATA drive adapter power supply which has both 5v 2amp and 12v 2amp coming out of the same power supply. \$\endgroup\$– jasonCommented Sep 27, 2013 at 21:36