diff --git a/addons/hw_escpos/__openerp__.py b/addons/hw_escpos/__openerp__.py
index 830b78300ea..127dbd5cf0b 100644
--- a/addons/hw_escpos/__openerp__.py
+++ b/addons/hw_escpos/__openerp__.py
@@ -37,6 +37,9 @@ that would need such functionality.
 """,
     'author': 'OpenERP SA',
     'depends': ['hw_proxy'],
+    'external_dependencies': {
+        'python' : ['usb.core','serial','qrcode'],
+    },
     'test': [
     ],
     'installable': True,
diff --git a/addons/hw_escpos/controllers/main.py b/addons/hw_escpos/controllers/main.py
index 78ed77a2318..d284d05dfdd 100644
--- a/addons/hw_escpos/controllers/main.py
+++ b/addons/hw_escpos/controllers/main.py
@@ -14,8 +14,6 @@ import usb.core
 from openerp.tools.translate import _
 from .. import escpos
 from ..escpos import printer
-#import escpos 
-#import escpos.printer
 from PIL import Image
 
 from openerp import http
@@ -29,6 +27,13 @@ class EscposDriver(hw_proxy.Proxy):
     supported_printers = [
         { 'vendor' : 0x04b8, 'product' : 0x0e03, 'name' : 'Epson TM-T20' }
     ]
+
+    def connected_usb_devices(self,devices):
+        connected = []
+        for device in devices:
+            if usb.core.find(idVendor=device['vendor'], idProduct=device['product']) != None:
+                connected.append(device)
+        return connected
     
     def get_escpos_printer(self):
         printers = self.connected_usb_devices(self.supported_printers)
diff --git a/addons/hw_proxy/controllers/main.py b/addons/hw_proxy/controllers/main.py
index 967323ae0d6..6ddf94843fd 100644
--- a/addons/hw_proxy/controllers/main.py
+++ b/addons/hw_proxy/controllers/main.py
@@ -7,30 +7,21 @@ import openerp
 import time
 import random
 import subprocess
-import usb.core
-import escpos 
-import escpos.printer
 import werkzeug
 import werkzeug.wrappers
+_logger = logging.getLogger(__name__)
+
 
 from openerp import http
 from openerp.http import request
 from openerp.addons.web.controllers.main import manifest_list, module_boot, html_template
 
-_logger = logging.getLogger(__name__)
 
 class Proxy(http.Controller):
     def __init__(self):
         self.scale = 'closed'
         self.scale_weight = 0.0
 
-    def connected_usb_devices(self,devices):
-        connected = []
-        for device in devices:
-            if usb.core.find(idVendor=device['vendor'], idProduct=device['product']) != None:
-                connected.append(device)
-        return connected
-
     @http.route('/hw_proxy/hello', type='http', auth='admin')
     def helloajx(self):
         return request.make_response('ping', {
diff --git a/addons/hw_scanner/controllers/main.py b/addons/hw_scanner/controllers/main.py
index ec56a733671..69fd29f5128 100644
--- a/addons/hw_scanner/controllers/main.py
+++ b/addons/hw_scanner/controllers/main.py
@@ -12,7 +12,12 @@ from openerp.http import request
 
 _logger = logging.getLogger(__name__)
 
-from evdev import InputDevice, ecodes, categorize, list_devices
+try:
+    import evdev
+except ImportError:
+    _logger.error('OpenERP module hw_scanner depends on the evdev python module')
+    evdev = None
+
 from select import select
 
 class ScannerDriver(hw_proxy.Proxy):
@@ -76,13 +81,15 @@ class ScannerDriver(hw_proxy.Proxy):
         }
 
     def get_device(self):
+        if not evdev:
+            return None
         devices   = [ device for device in listdir(self.input_dir)]
         keyboards = [ device for device in devices if 'kbd' in device ]
         scanners  = [ device for device in devices if ('barcode' in device.lower()) or ('scanner' in device.lower()) ]
         if len(scanners) > 0:
-            return InputDevice(join(self.input_dir,scanners[0]))
+            return evdev.InputDevice(join(self.input_dir,scanners[0]))
         elif len(keyboards) > 0:
-            return InputDevice(join(self.input_dir,keyboards[0]))
+            return evdev.InputDevice(join(self.input_dir,keyboards[0]))
         else:
             return None
 
@@ -105,9 +112,9 @@ class ScannerDriver(hw_proxy.Proxy):
                 device.ungrab()
                 return ''
             for event in device.read():
-                if event.type == ecodes.EV_KEY:
+                if event.type == evdev.ecodes.EV_KEY:
+                    #_logger.debug('Evdev Keyboard event %s',evdev.categorize(event))
                     if event.value == 1: # keydown events
-                        #print categorize(event)
                         if event.code in self.keymap: 
                             if shift:
                                 barcode.append(self.keymap[event.code][1])