diff --git a/CHANGELOG.txt b/CHANGELOG.txt
index d21f2a8..79c6a76 100644
--- a/CHANGELOG.txt
+++ b/CHANGELOG.txt
@@ -9,7 +9,12 @@ Change Log
 ------------------
 - Second Release
 
-0.0.3 (27/10/2020)
+0.0.3 (28/10/2020)
 ------------------
 - third Release
 - fix bugs
+
+0.0.4 (30/10/2020)
+------------------
+- fourth Release
+- fix bugs
diff --git a/README.md b/README.md
index 383ad02..58308e3 100644
--- a/README.md
+++ b/README.md
@@ -17,8 +17,8 @@ import pcf8574_io
 
 # you can use up to 8 PCF8574 boards 0x20 and 0x21 are the I2C addresses
 # true will set all the pins HIGH +5v false will set them to LOW 0v 
-p1 = pcf8574_io.PCF(0x20, True)
-p2 = pcf8574_io.PCF(0x21, False)
+p1 = pcf8574_io
+p2 = pcf8574_io
 
 # p0 to p7 are the pins name
 # INPUT or OUTPUT is the mode
diff --git a/pcf8574_io/PCF85.py b/pcf8574_io/PCF85.py
index cfe94f5..ec91a9c 100644
--- a/pcf8574_io/PCF85.py
+++ b/pcf8574_io/PCF85.py
@@ -1,139 +1,76 @@
 from smbus2 import SMBus
-
-pinModeFlag = 0x00
-PCFAddress = 0x20
-smBusNum = 1
-writeData = 0x00
+import math
 
 
 def setup(PCFAdd, smBus, status):
-    global pinModeFlag, writeData, PCFAddress, smBusNum
-    pinModeFlag = 0x00
-    PCFAddress = PCFAdd
-    smBusNum = smBus
-    writeData = 0x00
     if status:
-        with SMBus(smBusNum) as bus:
-            b = bus.write_byte(PCFAddress, 0xFF)
+        with SMBus(smBus) as bus:
+            bus.write_byte(PCFAdd, 0xFF)
     elif not status:
-        with SMBus(smBusNum) as bus:
-            b = bus.write_byte(PCFAddress, 0x00)
-
-
-# mode INPUT 0,OUTPUT 1
-def pin_mode(pinName, mode):
-    global pinModeFlag
-    if "p0" in pinName.strip():
-        set_mode(pinName, mode, 0, 0x01)
-    elif "p1" in pinName.strip():
-        set_mode(pinName, mode, 1, 0x02)
-    elif "p2" in pinName.strip():
-        set_mode(pinName, mode, 2, 0x04)
-    elif "p3" in pinName.strip():
-        set_mode(pinName, mode, 3, 0x08)
-    elif "p4" in pinName.strip():
-        set_mode(pinName, mode, 4, 0x10)
-    elif "p5" in pinName.strip():
-        set_mode(pinName, mode, 5, 0x20)
-    elif "p6" in pinName.strip():
-        set_mode(pinName, mode, 6, 0x40)
-    elif "p7" in pinName.strip():
-        set_mode(pinName, mode, 7, 0x80)
+        with SMBus(smBus) as bus:
+            bus.write_byte(PCFAdd, 0x00)
+
+
+def pin_mode(pinName, mode, flg):
+    return set_mode(pinNameToNum(pinName), mode, flg, int(math.pow(2, pinNameToNum(pinName))))
+
+
+def set_mode(pnNum, mode, rValue, flg):
+    if "INPUT" in mode.strip() and isKthBitSet(flg, pnNum + 1):
+        flg = flg - rValue
+        return flg
+    elif "OUTPUT" in mode.strip() and not isKthBitSet(flg, pnNum + 1):
+        flg = flg + rValue
+        return flg
     else:
-        print("Wrong Pin Name!")
+        return flg
 
 
-def isKthBitSet(n, k):
-    if n & (1 << (k - 1)):
+def digitalRead(pinName, smbs, addr):
+    with SMBus(smbs) as bus:
+        b = bus.read_byte(addr)
+    if isKthBitSet(b, pinNameToNum(pinName)):
         return True
     else:
         return False
 
 
-def read_data(pinNum):
-    with SMBus(smBusNum) as bus:
-        b = bus.read_byte(PCFAddress)
-    if isKthBitSet(b, pinNum):
-        return True
+def pinNameToNum(pinName):
+    pn = pinName.strip().replace("p", "").strip()
+    if pn in range(8):
+        return pn
     else:
-        return False
+        print("pin name error!")
 
 
-def write_data(pinName, val):
-    if "p0" in pinName.strip():
-        set_write(pinName, 0, 0x01, val)
-    if "p1" in pinName.strip():
-        set_write(pinName, 1, 0x02, val)
-    if "p2" in pinName.strip():
-        set_write(pinName, 2, 0x04, val)
-    if "p3" in pinName.strip():
-        set_write(pinName, 3, 0x08, val)
-    if "p4" in pinName.strip():
-        set_write(pinName, 4, 0x10, val)
-    if "p5" in pinName.strip():
-        set_write(pinName, 5, 0x20, val)
-    if "p6" in pinName.strip():
-        set_write(pinName, 6, 0x40, val)
-    if "p7" in pinName.strip():
-        set_write(pinName, 7, 0x80, val)
-
-
-def set_mode(pinName, mode, pValue, rValue):
-    global pinModeFlag
-    cValue = pValue + 1
-    if "p" + str(pValue) in pinName.strip():
-        if "INPUT" in mode.strip() and isKthBitSet(pinModeFlag, cValue):
-            pinModeFlag = pinModeFlag - rValue
-        elif "OUTPUT" in mode.strip() and not isKthBitSet(pinModeFlag, cValue):
-            pinModeFlag = pinModeFlag + rValue
-        else:
-            print("Wrong IO Mode")
-
-
-def set_write(pinName, pValue, rValue, val):
-    global writeData
-    with SMBus(smBusNum) as bus:
-        b = bus.read_byte(PCFAddress)
-    writeData = b
-    cValue = pValue + 1
-    if "p" + str(pValue) in pinName.strip():
-        if val == 0 and isKthBitSet(writeData, cValue):
-            writeData = writeData - rValue
-            with SMBus(smBusNum) as bus:
-                bus.write_byte(PCFAddress, writeData)
-
-        elif val == 1 and not isKthBitSet(writeData, cValue):
-            writeData = writeData + rValue
-            with SMBus(smBusNum) as bus:
-                bus.write_byte(PCFAddress, writeData)
-
-
-def checkPinNum(pinName):
-    if 0 < int(pinName.strip().replace("p")) < 8:
+def isKthBitSet(n, k):
+    if n & (1 << (k - 1)):
         return True
     else:
         return False
 
 
-def digitalRead(pinName):
-    global pinModeFlag
-    cValue = int(pinName.strip().replace("p", "")) + 1
-    return read_data(cValue)
-
-
-def digitalWrite(pinName, val):
-    global pinModeFlag
-    cValue = int(pinName.strip().replace("p", "")) + 1
-    if isKthBitSet(pinModeFlag, cValue):
+def digitalWrite(pinName, val, addr, flg):
+    if isKthBitSet(flg, pinNameToNum(pinName)+1):
         if "HIGH" in val.strip():
-            write_data(pinName, 1)
+            write_data(pinNameToNum(pinName), 1, flg, addr)
         elif "LOW" in val.strip():
-            write_data(pinName, 0)
+            write_data(pinNameToNum(pinName), 0, flg, addr)
     else:
         print("You can not Write Input Pin")
 
-# pin_mode("p0", "INPUT")
-# digitalRead("p0")
-# digitalWrite("p0", "HIGH")
 
-# print("{0:b}".format(pinModeFlag))
+def write_data(pnNum, val, smbs, flg, addr):
+    if isKthBitSet(flg, pnNum+1):
+        with SMBus(smbs) as bus:
+            wr = bus.read_byte(addr)
+        if val == 0 and isKthBitSet(wr, pnNum+1):
+            wr = wr - int(math.pow(2, pnNum))
+            with SMBus(smbs) as bus:
+                bus.write_byte(addr, wr)
+        elif val == 1 and not isKthBitSet(wr, pnNum+1):
+            wr = wr + int(math.pow(2, pnNum))
+            with SMBus(smbs) as bus:
+                bus.write_byte(addr, wr)
+
+
diff --git a/pcf8574_io/__init__.py b/pcf8574_io/__init__.py
index 41c7fc1..0ef9c62 100644
--- a/pcf8574_io/__init__.py
+++ b/pcf8574_io/__init__.py
@@ -6,14 +6,15 @@ class PCF:
     def __init__(self, address, status):
         self.address = address
         self.status = status
-        PCF85.setup(address, 1, status)
+        self.pinModeFlag = 0x00
+        self.smBusNum = 1
+        PCF85.setup(address, self.smBusNum, status)
 
     def pin_mode(self, PinName, Mode):
-        return PCF85.pin_mode(PinName, Mode)
+        self.pinModeFlag = PCF85.pin_mode(PinName, Mode, self.pinModeFlag)
 
     def digital_read(self, PinName):
-        return PCF85.digitalRead(PinName)
+        return PCF85.digitalRead(PinName, self.smBusNum, self.address)
 
     def digital_write(self, PinName, Val):
-        return PCF85.digitalWrite(PinName, Val)
-
+        PCF85.digitalWrite(PinName, Val, self.address, self.pinModeFlag)
diff --git a/setup.py b/setup.py
index 96a44c3..8d2f50a 100644
--- a/setup.py
+++ b/setup.py
@@ -11,7 +11,7 @@
 
 setup(
     name='pcf8574_io',
-    version='0.0.3',
+    version='0.0.4',
     description='setup pin mode and read, write to PCF8574 pins',
     long_description=open('README.txt').read() + '\n\n' + open('CHANGELOG.txt').read(),
     url='',
diff --git a/test.py b/test.py
index c8b8a4e..81a301d 100644
--- a/test.py
+++ b/test.py
@@ -1,8 +1,8 @@
 import pcf8574_io
 
 # you can use up to 8 PCF8574 boards
-p1 = pcf8574_io.PCF(0x20, True)
-p2 = pcf8574_io.PCF(0x21, False)
+p1 = pcf8574_io
+p2 = pcf8574_io
 
 # p0 to p7 are the pins name
 # INPUT or OUTPUT is the mode