diff --git a/tests/.gitignore b/tests/.gitignore
new file mode 100644
index 000000000..f47cb2045
--- /dev/null
+++ b/tests/.gitignore
@@ -0,0 +1 @@
+*.out
diff --git a/trezorlib/client.py b/trezorlib/client.py
index 34ecefd64..495a6a1d2 100644
--- a/trezorlib/client.py
+++ b/trezorlib/client.py
@@ -4,10 +4,13 @@ import time
 import binascii
 import hashlib
 import unicodedata
+import mapping
+import json
 
 import tools
 import messages_pb2 as proto
 import types_pb2 as types
+import protobuf_json
 from trezorlib.debuglink import DebugLink
 from mnemonic import Mnemonic
 
@@ -19,10 +22,17 @@ def get_buttonrequest_value(code):
     return [ k for k, v in types.ButtonRequestType.items() if v == code][0]
 
 def pprint(msg):
+    msg_class = msg.__class__.__name__
+    msg_size = msg.ByteSize()
+    """
+    msg_ser = msg.SerializeToString()
+    msg_id = mapping.get_type(msg)
+    msg_json = json.dumps(protobuf_json.pb2json(msg))
+    """
     if isinstance(msg, proto.FirmwareUpload):
-        return "<%s> (%d bytes):\n" % (msg.__class__.__name__, msg.ByteSize())
+        return "<%s> (%d bytes):\n" % (msg_class, msg_size)
     else:
-        return "<%s> (%d bytes):\n%s" % (msg.__class__.__name__, msg.ByteSize(), msg)
+        return "<%s> (%d bytes):\n%s" % (msg_class, msg_size, msg)
 
 def log(msg):
     sys.stderr.write("%s\n" % msg)
diff --git a/trezorlib/protobuf_json.py b/trezorlib/protobuf_json.py
index 2704fef6c..0ba7d26ba 100644
--- a/trezorlib/protobuf_json.py
+++ b/trezorlib/protobuf_json.py
@@ -37,12 +37,13 @@ Provide serialization and de-serialization of Google's protobuf Messages into/fr
 # Note that preservation of unknown fields is currently not available for Python (c) google docs
 # extensions is not supported from 0.0.5 (due to gpb2.3 changes)
 
-__version__ = '0.0.5'
-__author__ = 'Paul Dovbush <dpp@dpp.su>'
+__version__='0.0.5'
+__author__='Paul Dovbush <dpp@dpp.su>'
 
 
-import json  # py2.6+ TODO: add support for other JSON serialization modules
+import json    # py2.6+ TODO: add support for other JSON serialization modules
 from google.protobuf.descriptor import FieldDescriptor as FD
+import binascii
 
 
 class ParseError(Exception): pass
@@ -58,7 +59,7 @@ def json2pb(pb, js):
         elif field.type in _js2ftype:
             ftype = _js2ftype[field.type]
         else:
-            raise ParseError("Field %s.%s of type '%d' is not supported" % (pb.__class__.__name__, field.name, field.type,))
+            raise ParseError("Field %s.%s of type '%d' is not supported" % (pb.__class__.__name__, field.name, field.type, ))
         value = js[field.name]
         if field.label == FD.LABEL_REPEATED:
             pb_value = getattr(pb, field.name, None)
@@ -76,17 +77,18 @@ def json2pb(pb, js):
 
 
 
-def pb2json(pb, js={}):
+def pb2json(pb):
     ''' convert google.protobuf.descriptor instance to JSON string '''
+    js = {}
     # fields = pb.DESCRIPTOR.fields #all fields
-    fields = pb.ListFields()  # only filled (including extensions)
-    for field, value in fields:
+    fields = pb.ListFields()    #only filled (including extensions)
+    for field,value in fields:
         if field.type == FD.TYPE_MESSAGE:
             ftype = pb2json
         elif field.type in _ftype2js:
             ftype = _ftype2js[field.type]
         else:
-            raise ParseError("Field %s.%s of type '%d' is not supported" % (pb.__class__.__name__, field.name, field.type,))
+            raise ParseError("Field %s.%s of type '%d' is not supported" % (pb.__class__.__name__, field.name, field.type, ))
         if field.label == FD.LABEL_REPEATED:
             js_value = []
             for v in value:
@@ -107,8 +109,8 @@ _ftype2js = {
     FD.TYPE_FIXED32: float,
     FD.TYPE_BOOL: bool,
     FD.TYPE_STRING: unicode,
-    # FD.TYPE_MESSAGE: pb2json,        #handled specially
-    FD.TYPE_BYTES: lambda x: x.encode('string_escape'),
+    #FD.TYPE_MESSAGE: pb2json,        #handled specially
+    FD.TYPE_BYTES: lambda x: binascii.hexlify(x),
     FD.TYPE_UINT32: int,
     FD.TYPE_ENUM: int,
     FD.TYPE_SFIXED32: float,
@@ -128,7 +130,7 @@ _js2ftype = {
     FD.TYPE_BOOL: bool,
     FD.TYPE_STRING: unicode,
     # FD.TYPE_MESSAGE: json2pb,    #handled specially
-    FD.TYPE_BYTES: lambda x: x.decode('string_escape'),
+    FD.TYPE_BYTES: lambda x: binascii.unhexlify(x),
     FD.TYPE_UINT32: int,
     FD.TYPE_ENUM: int,
     FD.TYPE_SFIXED32: float,