Go Down

Topic: Arduino nano and DFmini player with external power (Read 1 time) previous topic - next topic

krisferrari

Jan 22, 2020, 07:27 pm Last Edit: Jan 22, 2020, 07:30 pm by krisferrari
Hello

I would like to play DFmini using external power, and Arduino only as a trigger. I am not sure, which pins to use.
When I put 3.7v 18650 to DFMini VCC and GND,  and connect Ground from DFMini to ground on Nano, I see that Nano is getting some power.  So I am assuming this is wrong.


If nanos 5v and GND are connected to VCC and GND pins of DF Mini, it works. But I am not interested , I want to use external power fro DFMini.

Any help for Karma :)



Power_Broker

Did you make sure the GND pins of the power supply, Arduino, and DFPlayer are all connected to each other?
"The desire that guides me in all I do is the desire to harness the forces of nature to the service of mankind."
   - Nikola Tesla

krisferrari

Did you make sure the GND pins of the power supply, Arduino, and DFPlayer are all connected to each other?
Power supply to arduino is now via USB. I need to be sure that DFPlayer is detected.

Arduino power supply is different from DFMIni power supply [in my scenario]. Lets me know, which grounds to be connected.

 Scenario: power supplied to  DFMini VCC and GND. good
Now took ground pin from DFmini to 1 of Nano's GND, I seea small led powering up. I dont know if that is ok or not, as at this time Arduino is not powered at all.

wvmarle

Grounds must be connected. All of them. That includes BOTH ground pins of the DF Player Mini.

Note that there is a risk of phantom powering the Arduino through the Tx/Rx pins when it receives no power, but the DF Player does, and the other way around.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

krisferrari

Grounds must be connected. All of them. That includes BOTH ground pins of the DF Player Mini.

Note that there is a risk of phantom powering the Arduino through the Tx/Rx pins when it receives no power, but the DF Player does, and the other way around.
ok. thanks

How big is that Phantom powering risk? I dont want to brick my parts. If connecting GNDs is not a good idea, then any alternate please.

Also the reason for supplying different battery power inputs is because Nano is serving a different purpose, and may not be turned on always. [DF is always powered on]

please advice

wvmarle

Connecting grounds is not just a good idea, it's mandatory for things to work.

Phantom powering can always happen when two devices are connected through I/O pins, while one is powered and the other not. Simple solution: power them both from the same supply. Resistors in the I/O lines can help prevent any damage.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

krisferrari

Connecting grounds is not just a good idea, it's mandatory for things to work.

Phantom powering can always happen when two devices are connected through I/O pins, while one is powered and the other not. Simple solution: power them both from the same supply. Resistors in the I/O lines can help prevent any damage.
This is my setup limitation. I cant power up both. Nano is driving some motor,  and want DF player to run standalone . Arduino is only required to trigger automatic start, without the need to press button. If Arduno is powered, the motor will  also run [ not needed]

About resistors solution can you draw something or paste a link.

Power_Broker

You don't need resistors, just connect the grounds and you'll be good to go!

If both the Nano and the MP3 player are always powered on together (even with separate supplies), why care about phantom power? Also, why not power the Arduino, the motors, and MP3 player off the same external power supply? Would work perfectly that way.
"The desire that guides me in all I do is the desire to harness the forces of nature to the service of mankind."
   - Nikola Tesla

wvmarle

1k resistors on the Tx/Rx lines between Arduino and DF Player (both of them, OP's schematic only shows one) help a lot keeping the sound from distorting. No idea why, but from experience I know it's a good idea to place those resistors there.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

krisferrari

You don't need resistors, just connect the grounds and you'll be good to go!

If both the Nano and the MP3 player are always powered on together (even with separate supplies), why care about phantom power? Also, why not power the Arduino, the motors, and MP3 player off the same external power supply? Would work perfectly that way.
As mentioned, I want to keep them as 2 different features. So powering both is not what I want.

Resistors thing , yes, I see suggestions to use 1K resistor , for  connection from Arduino to DF, and I am using 1.

My problem still remains open.
I was suggested the link. https://forum.arduino.cc/index.php?topic=540000.msg3680701#msg3680701
need to look at it this weekend

Power_Broker

As mentioned, I want to keep them as 2 different features. So powering both is not what I want.
Why? What functionality does that give you? I'm not saying it's a bad decision, but without knowing what your project is and what you want it to do, there's no way of knowing why you're making this odd decision.

Even still, if you want to independently select which electronics are turned on at specific times, you can just use switches in conjunction with a single power supply. Same functionality with less mess.
"The desire that guides me in all I do is the desire to harness the forces of nature to the service of mankind."
   - Nikola Tesla

Go Up