Turn on DFPlayer with 08M

jmumby

Senior Member
I have a CHI040 and I want to turn on a DFPlayer same as in the SPE035. So I have hooked it up as below.

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The reason I want to do this is the player uses a huge amount of current when doing nothing. It may need to turn on for 30 seconds a day, at the moment when it is idle the circuit consumes 100+ mA. If the speakers are not connected the current is quite low, when they are connected the current goes up. If I connect the GND of the speaker to that of the DFPlayer, the player does not work at all.

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So the amp must be drawing current via the GND and 4.5V.
 

AllyCat

Senior Member
Hi,

You haven't shown any "control" (logic input) connections to the DFPlayer ?

It would be better (any maybe essential) to control the power through a "High-Side Switch", e.g. a PNP transistor to the supply rail, which shouldn't be difficult if it and the PICaxe have a common supply voltage. At the moment you're not really "disconnecting" the DFPlayer, because it's still connected to the supply rail and to Ground via the Loudspeaker(s).

Alternatively, it may be that the amplifier built into the DFPlayer is "unsuitable" to use with your speakers (or the way you're using them). So you might consider an external amplifier, perhaps the excellent little PAM8403 module?

Cheers, Alan.
 

inglewoodpete

Senior Member
I doubt that the quench diode across the DF Player is doing anything.

What sort of current does the player require? A BC548's data sheet indicates that it has an "Absolute Maximum" collector current of 100mA.
 

jmumby

Senior Member
You haven't shown any "control" (logic input) connections to the DFPlayer
For simplicity I left this out. I am controlling the unit serially. I will try the high side switch as you mention and then a pam8403. Hopefully that won't have the same issue. It is just for a picture frame so the inbuilt amp is adequate.
 

AllyCat

Senior Member
Hi,

A High Side switch (e.g. BC327) should solve the problem, but as the DFPlayer's serial interface is Idle-High you might also want to take it Low or Tri-State (set as INPUT) during shut-down.

Alternatively, the PAM8403 idles at about 5 mA, but most Breakout PCBs tie its Enable (/Shutdown) pin directly to the supply rail. However, the IC pin can be lifted (unsoldered) from the PCB, or there is a version usually described as "... for Bluetooth Input" which costs little more (where available) and brings both the /Mute and /Shutdown inputs out to pins.

Cheers, Alan.
 

tmfkam

Senior Member
Are the speakers meant to be connected like that? I thought the audio out from the SPE035 was a bridge output, referencing it to earth could result in excess power consumption and possibly damage the amp on the SPE035. The speaker out is not left and right but a mono output with the speaker connected between the two speaker terminals, not to ground at all.
 

AllyCat

Senior Member
Hi,

Ah yes, the speaker is very probably wired as an "H-bridge" (as they are also with the PAM8403) to avoid the need for a coupling capacitor. I was "suspicious" about the reported high quiescent current and that schematic, but the "Circuit Diagram" in the SPE035 manual is still marked "TODO". :(

However, the text does say : "The 8 ohm speaker is connected to SPK1 and SPK2. "

Cheers, Alan.
 

1968neil

Senior Member
Ive used 100's of these boards in projects and as others say the speaker terminals are isolated from ground.
I also feed the supply into the module via a 1N4007 this drops the supply enough to run it from 5v.
If you want to switch the supply a high side switch is always best in this set up.
I also would add a resistor to ground from at the base of your transistor to be sure it stays off when doing other things :) (100K is fine)
If you are using an external amplifier (recommended) you can take the DAC outputs out as a stereo pair :)

Regards
Neil
 
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