Wifi switched off, 80MHz MCU and lower volume

vscode/RamsachMp3Glocke/platformio.ini

@@ -14,3 +14,6 @@ board = d1_mini_pro
 framework = arduino
 monitor_speed = 115200
 lib_deps = salvadorrueda/SerialMP3Player@^1.1.0
+
+; set frequency to 160MHz
+board_build.f_cpu = 80000000L

vscode/RamsachMp3Glocke/src/main.cpp

@@ -1,4 +1,5 @@
 #include "SerialMP3Player.h"
+#include <ESP8266WiFi.h>
 
 #define TX D3
 #define RX D2
@@ -35,15 +36,24 @@ bool button_pressed(unsigned int button_pin){
 }
 
 void setup() {
+
   Serial.begin(115200);     // start serial interface
   pinMode(BUTTON,INPUT_PULLUP);
 
+  WiFi.mode(WIFI_OFF);
+  WiFi.forceSleepBegin();
+  delay(10);
+
   mp3.begin(9600);        // start mp3-communication
   delay(500);             // wait for init
 
+
+  mp3.setVol(25);
+  delay(500);
+  
   mp3.sendCommand(CMD_SEL_DEV, 0, 2);   //select sd-card
   delay(500);             // wait for init
-  mp3.setVol(30);
+ 
 }
 
 // the loop function runs over and over again forever