diff --git a/androidBluetoothSerial/src/main/java/com/harrysoft/androidbluetoothserial/SimpleBluetoothDeviceInterface.kt b/androidBluetoothSerial/src/main/java/com/harrysoft/androidbluetoothserial/SimpleBluetoothDeviceInterface.kt
index 689f6ee..4fff64d 100644
--- a/androidBluetoothSerial/src/main/java/com/harrysoft/androidbluetoothserial/SimpleBluetoothDeviceInterface.kt
+++ b/androidBluetoothSerial/src/main/java/com/harrysoft/androidbluetoothserial/SimpleBluetoothDeviceInterface.kt
@@ -1,5 +1,8 @@
 package com.harrysoft.androidbluetoothserial
 
+import java.io.InputStream
+import java.io.OutputStream
+
 interface SimpleBluetoothDeviceInterface {
     /**
      * @return The BluetoothSerialDevice instance that the interface is wrapping.
@@ -51,4 +54,7 @@ interface SimpleBluetoothDeviceInterface {
     interface OnErrorListener {
         fun onError(error: Throwable)
     }
+
+    fun getOutputStream(): OutputStream
+    fun getInputStream(): InputStream
 }
diff --git a/androidBluetoothSerial/src/main/java/com/harrysoft/androidbluetoothserial/SimpleBluetoothDeviceInterfaceImpl.kt b/androidBluetoothSerial/src/main/java/com/harrysoft/androidbluetoothserial/SimpleBluetoothDeviceInterfaceImpl.kt
index cd15c77..49f72e1 100644
--- a/androidBluetoothSerial/src/main/java/com/harrysoft/androidbluetoothserial/SimpleBluetoothDeviceInterfaceImpl.kt
+++ b/androidBluetoothSerial/src/main/java/com/harrysoft/androidbluetoothserial/SimpleBluetoothDeviceInterfaceImpl.kt
@@ -3,6 +3,8 @@ package com.harrysoft.androidbluetoothserial
 import io.reactivex.android.schedulers.AndroidSchedulers
 import io.reactivex.disposables.CompositeDisposable
 import io.reactivex.schedulers.Schedulers
+import java.io.InputStream
+import java.io.OutputStream
 
 /**
  * Implementation of SimpleBluetoothDeviceInterface, package-private
@@ -49,6 +51,14 @@ internal class SimpleBluetoothDeviceInterfaceImpl(override val device: Bluetooth
         errorListener = listener
     }
 
+    override fun getOutputStream(): OutputStream {
+        return device.outputStream
+    }
+
+    override fun getInputStream(): InputStream {
+        return device.inputStream
+    }
+
     fun close() {
         compositeDisposable.dispose()
     }
diff --git a/build.gradle b/build.gradle
index dfa20b9..74a857c 100644
--- a/build.gradle
+++ b/build.gradle
@@ -5,7 +5,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.5.3'
+        classpath 'com.android.tools.build:gradle:4.2.2'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
diff --git a/gradle.properties b/gradle.properties
index 743d692..2de2ee2 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -11,3 +11,6 @@ org.gradle.jvmargs=-Xmx1536m
 # This option should only be used with decoupled projects. More details, visit
 # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
 # org.gradle.parallel=true
+
+android.useAndroidX=true
+android.enableJetifier=true
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 80feee7..c94dce2 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.4-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.7.1-all.zip