procedure Interrupt;
begin
  if TestBit(INTCON, RBIF) = 1 then
  begin
    New := (PORTB and %11000000);
    if New <> Old then
    begin
      bInc := (New.7 xor Old.6);
      bValueChanged := true;
      Old := New;
    end;
    ClearBit(INTCON, RBIF);
  end;
end;

begin
  while true do
  begin
    Delay_ms(1);
    if bValueChanged then
    begin
      if bInc then
      begin 
        PORTA.0 := true;   // led D1 allumée
        inc(Value);        // augmentation valeur
      end
      else
      begin
        PORTA.0 := false;  // led D1 éteinte
        dec(Value);        // diminution valeur
      end;
      bValueChanged := false;
    end
    else
      nop;
  end;
end;