dialog - How to Catch Input from Card Reader Pin Pad -

i new android. currently, developing application performs credit card transaction each time payment made, phone connected card reader through audio jack port. in order make payment successful, credit card authorized user needs enter pin(pin entered card reader). @ stage, application prompt dialog box request user enter pin. so, here hardest part. when dialog box appears, user shall enter pin number pin pad(from card reader connected phone) instead of entering soft keypad(from phone).i have been googled around seems haven't met looked , noticed in order this, need implement input method manager. still figuring out how can done , appreciate if of me solution. in advance

here code dialog box appears

final edittext et = new edittext(iccardactivity.this);                                               new alertdialog.builder(iccardactivity.this)                                 .settitle(title)                                 .setview(et)                                 .setpositivebutton("ok",                                         new dialoginterface.onclicklistener() {                                             @override                                             public void onclick(                                                     dialoginterface arg0,                                                     int arg1) {                                                 _pin = et.gettext().tostring();                                             }                                         })                                 .setnegativebutton("cancel",                                         new dialoginterface.onclicklistener() {                                             @override                                             public void onclick(                                                     dialoginterface arg0,                                                     int arg1) {                                                 _pin = "";                                             }                                         }).show();                         sendmessage(title + " pinpad! try count=" + ucpintrycnt);