DFPlayerMini volume increase

Projects General Guidance
1

Arduino UnoR3 with DFPlayerMini (with lib from https://github.com/PowerBroker2/DFPlayerMini_Fast) increases volume from initial to max in steps of three or four. Is this caused by any previous .volumeAdjustSet() or some fancy fade in on certain modules I read about? If so, how to reset that?

#include <Arduino.h>
#include <DFPlayerMini_Fast.h>
#include <SoftwareSerial.h>
SoftwareSerial softSerial(10, 11); // RX, TX

DFPlayerMini_Fast MP3Player;

void setup()
{
  Serial.begin(115200);
  softSerial.begin(9600);
  while (!MP3Player.begin(softSerial))  //, true))
    delay(500);
  MP3Player.volume(5); // Set initial volume
  MP3Player.playFromMP3Folder(4);
}

void loop()
{
  char buf[4];
  Serial.print("Starting volume: "); Serial.println(lowByte(MP3Player.currentVolume()));
  Serial.print("Current volume: ");
  while (MP3Player.isPlaying())
  {
    sprintf(buf, "%2d ", lowByte(MP3Player.currentVolume()));
    Serial.print(buf);
    delay(500);
  }
  Serial.println();
  while (Serial.available() == 0) ;
}

Output of the above:

Starting volume: 5
Current volume: 5 8 12 16 19 23 26 30 30 30 30 30 30 30 30 30 30 30 30

Mny txs in advance

2

Check the documentation for the library! Information ought to be found there.

3

You format is requesting an int (2 bytes on Uno) but the function lowByte() is supplying a byte (1 byte). Just print the value directly without sprintf()

4

Works just fine for me with an Uno R3 and real DFplayerMini (not a clone) with 1.2K/2.2K level converter between Uno pin 11 and DFplayer Rx pin. 4 mp3 files in MP3 folder, 4th file plays, volume stays at 5.

5

@ Railroader: lib function does just what the module manual says. The problem is not the initial volume but the auto increase.
@blh64: sure could, but with a return range of 0 to 30 it's zero for the MSB always. Anyway, it's beside the point.
@van_der_decken: "level converters" ?? are in, as the UART is TTL anyway, this is just to eliminate some warble. And what's your experience with clones, as I don't have a "real" module, it seems.

6

The DFplayer Mini operates on 3.3V level signals.

The Uno R3 outputs a 5V level signal.

Therefore, level converter on the Rx line.

My experience with clones is that the poor man pays twice. Once for a cheap clone, then a second time for the real thing that works.

7

Sounds like a VOL+ button is pressed (bad wiring/coding for the button).

8

No buttons, but good point, will check the board it' mounted on, maybe there is some spurious voltage across the strips.

9

Bingo, bulls eye, on the nose. Tiny solder bridge between pins 10 and 11 (GND and I/O2).
Thanks for the nudge!

10

writing bad code is never beside the point

11

Another unsolicited "bad code" cry from the c-crowd. If I need a byte and get a byte I use a byte and have done so for more than 50 yrs programming. So, still not helpful (see #7). Case closed.