Cannot connect DFPlayer to Arduino Nano 33 IoT

[kazachenko]

Hello,
I am trying to connect DFPlayer to Arduino Nano 33 IoT.
I believe I cannot use SoftwareSerial there, but can use HardwareSerial Serial1, connection TX-RX and RX-TX. I also use external power supply for 5V, but it seems to be irrelevant. Player cannot be found with or without it (when Arduino is just connected to PC by USB).

The wiring

The code

#include "DFRobotDFPlayerMini.h"

// Create the DFPlayer Mini object.
DFRobotDFPlayerMini myDFPlayer;


void setup()
{
  Serial.begin(115200);

  // Initiate DFPlayer Mini on the second serial port on RX0 and TX1 pins.
  Serial1.begin(1200); // tried 9600 as well
  while(!myDFPlayer.begin(Serial1))  { Serial.println("Not Connected!"); }

  Serial.println("DFPlayer Connected!!!");
  myDFPlayer.setTimeOut(500); //Set serial communictaion time out 500ms
  //----Set volume----
  myDFPlayer.volume(30);  //Set volume value (0~30).
  // Set EQ
  myDFPlayer.EQ(DFPLAYER_EQ_NORMAL);
  // Set the SD Card as default source.
  myDFPlayer.outputDevice(DFPLAYER_DEVICE_SD);
}


void loop()
{
  myDFPlayer.play(1);
  delay(1000);
  myDFPlayer.play(2);
  delay(1000);

}

All I see in Serial Monitor is "Not Connected" messages.

Is there something wrong with my wiring? With the code? Any suggestions are appreciated.
TIA