diff --git a/python/biopro/device/device_cc2650.py b/python/biopro/device/device_cc2650.py
index 976b6b1..0558d94 100644
--- a/python/biopro/device/device_cc2650.py
+++ b/python/biopro/device/device_cc2650.py
@@ -2186,6 +2186,7 @@ class CC2650SingleMasterCentralDevice(CC2650MasterDevice, Synchronized):
 
         pack_len = connect_response[0]
         connect_ack = connect_response[1:pack_len+1]
+        print('connect_ack:', connect_ack)
         if pack_len == 1:
             if connect_ack[0] == 3:
                 connected = True
@@ -2205,6 +2206,7 @@ class CC2650SingleMasterCentralDevice(CC2650MasterDevice, Synchronized):
             dont_care = 0
             self._device = ret = CC2650Device(device_id=dont_care, master=self, response_info=response)
             self.log_verbose('[CC2650]', DEVICE_CONNECTED, address_s)
+            sleep(2)
             return ret
 
         self.log_verbose('[CC2650]', 'connect fail')
@@ -2273,34 +2275,45 @@ class CC2650SingleMasterCentralDevice(CC2650MasterDevice, Synchronized):
         ins.append(0xF1)
         self._interface.flush_input()
 
-        try:
-            self.log_verbose('[CC2650]', 'write_characteristic', device, str(hex(handle).upper()))
-            self.log_verbose('[CC2650]', 'write_characteristic att_write','0x'+str.upper(ins.hex()))
-            self._cc2650.send("bytes", bytes(ins))
-            
-        except SerialTimeoutException:
-            self.log_verbose('[CC2650]', 'write_characteristic send fail')
-
-        else:
+        for _ in range(5):
             try:
-                write_response = self._cc2650.recv_uart(0.5)
+                self.log_verbose('[CC2650]', 'write_characteristic', device, str(hex(handle).upper()))
+                self.log_verbose('[CC2650]', 'write_characteristic att_write','0x'+str.upper(ins.hex()))
+                self._cc2650.send("bytes", bytes(ins))
+                
+            except SerialTimeoutException:
+                self.log_verbose('[CC2650]', 'write_characteristic send fail')
 
-            except RecvTimeout:
-                self.log_verbose('[CC2650]', 'write_characteristic response timeout')
+            else:
+                try:
+                    write_response = self._cc2650.recv_uart(0.1)
+
+                except RecvTimeout:
+                    self.log_verbose('[CC2650]', 'write_characteristic response timeout, write retry')
+                    continue
+                else:
+                    pack_len = write_response[0]
+                    write_ack = write_response[1:pack_len+1]
+                    write_response_hex = ''.join(format(i, '02X') for i in write_response)
+                    if write_ack == [255]:
+                        self.log_verbose('[CC2650]', 'write_characteristic fail, write retry', '0x'+write_response_hex)
+                        continue
+                    else:
+                        break
 
         if write_response is None:
+            self.log_verbose('[CC2650]', 'write_characteristic fail')
             return False
                 
         pack_len = write_response[0]
         write_ack = write_response[1:pack_len+1]
-        
+        write_response_hex = ''.join(format(i, '02X') for i in write_response)
         if write_ack == [3]:
-            write_response_hex = ''.join(format(i, '02X') for i in write_response)
             self.log_verbose('[CC2650]', 'write_characteristic success', '0x'+write_response_hex)
             return True
-
-        self.log_verbose('[CC2650]', 'write_characteristic fail')
-        return False
+        else:
+            self.log_verbose('[CC2650]', 'write_characteristic fail', '0x'+write_response_hex)
+            return False
 
     @synchronized
     def read_characteristic(self, device: int, handle: int) -> Optional[bytes]:
@@ -2323,7 +2336,7 @@ class CC2650SingleMasterCentralDevice(CC2650MasterDevice, Synchronized):
 
         else:
             try:
-                read_response = self._cc2650.recv_uart(1)
+                read_response = self._cc2650.recv_uart(0.5)
 
             except RecvTimeout:
                 self.log_verbose('[CC2650]', 'read_characteristic response timeout')
diff --git a/python/biopro/devlib/device.py b/python/biopro/devlib/device.py
index 30b6f48..a759663 100644
--- a/python/biopro/devlib/device.py
+++ b/python/biopro/devlib/device.py
@@ -734,7 +734,7 @@ class DeviceCommonInstruction:
     # don't create DeviceCommonInstruction instance, just return tuple
     def __new__(cls, instruction: str) -> Optional[Tuple[str, ...]]:
         if instruction == cls.RESET:
-            return '_sync(False)', '_notify(False)', 'VIS_RST'
+            return '_sync(False)', 'VIS_RST'
         elif instruction == cls.START:
             return '_data_format("TDC4VAF2")', '_notify(True)', 'VIS_STI', '_sync(True)'
         elif instruction == cls.INTERRUPT:
diff --git a/python/biopro/devlib/instruction.py b/python/biopro/devlib/instruction.py
index 81e199e..840b346 100644
--- a/python/biopro/devlib/instruction.py
+++ b/python/biopro/devlib/instruction.py
@@ -794,6 +794,7 @@ class InstructionDataContent(InstructionContent):
                     offset += 1
 
                 else:
+                    buffer.extend([0]*(self._width.size-len(buffer)))
                     for i in range(self._width.size):
                         if self._width.little_endian:
                             value |= (buffer[offset] << (1 * i))