[LF 125kHz] Interfacing Arduino/HTRC110 - Read a tag

/*
 Connexions HTRC110 <--> Arduino
 > SCLK: HTRC110_pin8  -- Arduino_D13
 > DIN:  HTRC110_pin9  -- Arduino_D11
 > DOUT: HTRC110_pin10 -- Arduino_D12 
 */

// Variables
byte Cde  = B00000000;
byte Data = B10000001;

// Interface HTRC110 - Function transfer
// rappel: CLK-> 13, HTRC110_Din-> 11, HTRC110_Dout-> 12
byte Transfer(byte Cde)
{
  int Tdemi = 20; //µs
  int i;
  boolean b;
  byte Rep;
  // initialisation
  digitalWrite(13,HIGH); //CLK High
  delayMicroseconds(Tdemi);
  digitalWrite(11, LOW);
  delayMicroseconds(Tdemi);
  digitalWrite(11, HIGH);
  delayMicroseconds(Tdemi);
 //8 clock periods to send the commands
  for (i=7;i>=0;i--)
  {
    // Falling edge
    digitalWrite(13, LOW);
    b = bitRead(Cde,i);
    digitalWrite(11, b);
    delayMicroseconds(Tdemi);
    // Rising edge
    digitalWrite(13, HIGH);
    delayMicroseconds(Tdemi);
  }
  // 8 clocks period for data
  for (i=7;i>=0;i--){
    // Falling edge
    digitalWrite(13, LOW);
    delayMicroseconds(Tdemi);
    digitalWrite(13, HIGH);
    //Rising edge
    b = digitalRead(12);
    bitWrite(Rep,i,b);
    delayMicroseconds(Tdemi);
  }
  digitalWrite(13,LOW);
  digitalWrite(12,HIGH);
  digitalWrite(11,HIGH);
  return Rep; 
}


//------------------------
// Specific function to send the READ_TAG command
// '111' sent and clock low
void READmode()
{
  int Tdemi = 20; // en microseconde
  int i;
  int j;
  boolean b;
    // INIT
    digitalWrite(13,HIGH); //CLK High
    delayMicroseconds(Tdemi);
    digitalWrite(11, LOW);
    delayMicroseconds(Tdemi);
    digitalWrite(11, HIGH);
    delayMicroseconds(Tdemi);
// 3 clocks for the three '1'
  for (i=2;i>=0;i--){
    //falling
    digitalWrite(13, LOW);
    digitalWrite(11, 1);
    delayMicroseconds(Tdemi);
    // rising
    digitalWrite(13, HIGH);
    delayMicroseconds(Tdemi);
  }
  digitalWrite(13,LOW);
  delay(200);
   digitalWrite(13,HIGH);
}

//SETUP
void setup() { 
 // Serial
 Serial.begin(9600);
 Serial.print("Demarrage:\n");  
 //Link with HTRC110
 // CLK-> 13, HTRC110_Din-> 11, HTRC110_Dout-> 12
  pinMode(11,OUTPUT);
  pinMode(12,INPUT);
  pinMode(13,OUTPUT);
  delay(10);
}


//MAIN
void loop() {

digitalWrite(11,HIGH);
digitalWrite(12,HIGH);
digitalWrite(13,LOW);

//CONFIG PAGES
//Page 3
Transfer(B01110000);
delay(2);
//Page 0
Transfer(B01000011);
delay(2);
//Page 2
Transfer(B01101100);
delay(2);
//Page 1
Transfer(B01010000);
delay(2);

////-----------------------------------------------
//CALCULATING SAMPLING TIME
byte t_ant;
t_ant = Transfer(B00001000);
//Calculation
t_ant <<= 1;
t_ant += B00111111;
t_ant &= B00111111;
Serial.println("t_ant sent=");
Serial.println(t_ant);
delay(2);
//Set sampling time
Transfer((B10000000 | t_ant));
delay(2);
//Get sampling time
byte resp_samp_time;
resp_samp_time = Transfer(B00000010);
Serial.println("t_ant read=");
Serial.println(resp_samp_time);

////-----------------------------------------------


//-------------------------------------------------  
//GENERAL SETTLING SEQUENCE
Transfer(B01101011);
delay(4);
Transfer(B01101000);                                                                                                                                                                                                                                                                 
delay(1);
Transfer(B01100000);
delay(2);
//------------------------------------------------- 

READmode();

delay(1000);
}

Here is just my code.
Transfer : function to activate CLK, 16 clocks period, 8 to sent data, 8 to read Dout. Works ok, cause I read the registers.
Read_mode : special function for READ_TAG command. Send '111' and setup clok low. Looks like it works well too.
The command READ_TAG is well interpreted by the chip cause if I add a '1' or if I forget to set up CLK low, I don't have anything on DOUT.
At the moment, I have things on DOUT but erratic, whatever I do in the code.
I still can't see the commands on the 125kHz sin wave sent by the chip. No command are RF sent.

My setup is powered by USB and I just disconnect and reconnect when I update the registers.