I am utilizing two separate power supplies for my project. The first one is 12V to power the Arduino Zero using the VIN pin, the second power supply is 5V to power my LED Rings. The rings are 16 bits (individually addressable LED's.) From what I understand, the Arduino needs to be connected to power via the same GND cable that is used for LED's, but i the same time, i also need to run the GND wire from the 12V power supple to Arduino to power it. Connecting both GND cables from each power supply is causing the LED's to flicker when on, so I am not sure how to get this done. Please see the diagram attached.
No it isn't.
You need to connect both grounds in order for it to work correctly. If you find the LEDs are flickering it is down to something else. From the looks of it it is the total lack on ant capacitors in your circuit.
How many LEDs are you trying to power in total?
What is the current capacity of your 5V power supply?
You need at about 60mA of current per LED.
Your "diagram" is not very clear, what are those two 20 Pin boxes?
What sort of Arduino are you using?
Thanks for the replay.
The total number of LED's is 1008 LED's. Every time the button is pressed, each rings of LED's (16) is lit. I have 63 rings x 16 = 1008 LED's. I found that I need to inject power every 7th ring so I have 9 injection points.
The power supply that I am using for LED's is 5V Power Supply 70A 350W 110V / 220V AC.
These are the rings i am using.
2 two boxes in the diagram are just simple wiring terminals so I can access the 5V and GND more easily to run my injection wires. I am using these terminal instead of running all 9 positive and GND wires directly to the 5V power supply.
I am using Arduino Zero
I am pretty new to this, so i am not using any capacitors at the moment. Not sure were they are needed.
One possible reason:
Your schematic is missing a pull-up resistor on pin 6. That is OK if you use the internal pull-up in the software. If not, your input is floating resulting in random reads of 0 and 1 and the software will react on it. And hence possibly the flickering that you observe.
This is in general the connection diagram for addressable LEDs: **Quick Question About Connecting Two Power Sources** - #5 by LarryD.
@sterretje
Thanks for the reply.
I am using pull-up in the software so there is no issues there.
Don't be so sure. The internal pull up resistors are only weak about 30 to 50K. The do not pull up very hard especially with all that current floating about with no capacitors. Try a 4K7 pull up.
Arduino Zero
I also adjusted the 12V power supply to only give out about 10V. Arduino Zero needs 7v-12v so i want to be somewhere in the middle.
Big problem with that is it only provides 3V3 signals which are often not enough to drive an LED strip running at 5V.
Which board would you recommend? Nano didn't have enough memory, so I opted for zero
Often advised is to add two 74HCT14 (https://www.ti.com/lit/ds/symlink/sn74hct14.pdf) gates in series between the output of the Zero and the LED strip to overcome the voltage difference.
An alternative board can be a Mega (1000 addressable LEDs require 1000x3 = 3000 bytes of RAM when using the Adafruit_Neopixel or FastLED libraries).
The Zero is fine if you do a level shift on the output pin driving the LEDs. I use the 74LS14 chip. This contains 6 inverting buffers but you only need two of them.
Do not use level shifters designed for I2C use as they don't work fast enough for Neopixels.
I would also repeat the large capacitor at each power injection point along your strip.
Looking at your project photograph, I would say you are bound to run into flickering problems because of the lenth of cable run you have. Especially without capacitors.
I still don't know what those two 20 pin boxes are in your original diagram.
@Grumpy_Mike Thank you,
I am sorry for the newbie question, but what capacitors would you recommend (if you can provide Amazon link) and how do I connect them? Do I put them on each 5V positive wire between the power supply and LED ring?
There are the boxes
The Link in post #4 showed you how to fit one at the start. You wire them between the positive and negative pin at each injection point. You do this by soldering them making sure that the leads are as short as possible. The actual value is not so important. I showed 680uF in my diagram in post #12 but they were shown as 1000uF in post #4.
Never buy your components from Amazon they are at least twice the price you can get them from other sources. I don't know where in the world you are, but major distributes like DigiKey, Mouser, Farnell or Newark as they are called in the US.
Also with so many LEDs I suspect there is quite a delay in changing just one ring.
I dread to think how much RFI (Radio Frequency Interference) that lot will generate. Have you tried listening to it on a medium wave radio?
Thanks for all your help. I will incorporate the resistor on the led data wire and capacitors at every power injection point and helpfully that will fix the flickering problems.
Using a second power supply to supply 10~12V to power a device that runs at 3.3V is a crazy situation. I guess the below is why you are convinced it is necessary:
5V. This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board if it is not sufficiently regulated. We don't advise it.
In my opinion this PSU should be "sufficiently regulated" to allow you to power the Zero through it's 5V pin. If you are still concerned, measure it's voltage output at low load (all led rings off) and high load (so led rings on). It should be <10% away from 5V.
@Grumpy_Mike @sterretje would you agree? Any concerns or other checks you would recommend?
Yes I would agree.
The
Is a misnomer. If you must power it from the Vin and you have the choice then you don't want it to be in the middle of the range but at the lower end. This minimises the heat dissipate by the internal regulator.
But having said that then
The power supply in question is sufficiently regulated if it is an adjustable one.
You're actually right; I just did not think about that but my WS2812B setup with a Mega uses the below.
I use 2 power supplies of 5V / 20A for my for my WS2812B setup. One of them also feeds a small boost converter (9V to Vin) to feed the Mega. That way I do not have to worry about 5V from the onboard regulator feeding back into the USB port of the PC; it's just my way of safety measure.