diff --git a/CHANGELOG.md b/CHANGELOG.md
index d27e63d..8b8f8e2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,14 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [0.4.1] - 2023-09-23
+- Update readme with advanced interrupts insights
+  - kudos to ddowling for testing.
+  - add example
+- fix URL examples
+- add Wire1 example (ESP32 + RP2040)
+
+
 ## [0.4.0] - 2023-09-23
 - refactor API, begin()
 - update readme.md
diff --git a/LICENSE b/LICENSE
index d77cf66..9a9ac5a 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2013-2023 Rob Tillaart
+Copyright (c) 2013-2024 Rob Tillaart
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/PCF8574.cpp b/PCF8574.cpp
index ac7e8b0..4c91bf3 100644
--- a/PCF8574.cpp
+++ b/PCF8574.cpp
@@ -2,7 +2,7 @@
 //    FILE: PCF8574.cpp
 //  AUTHOR: Rob Tillaart
 //    DATE: 02-febr-2013
-// VERSION: 0.4.0
+// VERSION: 0.4.1
 // PURPOSE: Arduino library for PCF8574 - 8 channel I2C IO expander
 //     URL: https://github.com/RobTillaart/PCF8574
 //          http://forum.arduino.cc/index.php?topic=184800
diff --git a/PCF8574.h b/PCF8574.h
index 494383f..96c5bb6 100644
--- a/PCF8574.h
+++ b/PCF8574.h
@@ -3,7 +3,7 @@
 //    FILE: PCF8574.h
 //  AUTHOR: Rob Tillaart
 //    DATE: 02-febr-2013
-// VERSION: 0.4.0
+// VERSION: 0.4.1
 // PURPOSE: Arduino library for PCF8574 - 8 channel I2C IO expander
 //     URL: https://github.com/RobTillaart/PCF8574
 //          http://forum.arduino.cc/index.php?topic=184800
@@ -13,7 +13,7 @@
 #include "Wire.h"
 
 
-#define PCF8574_LIB_VERSION         (F("0.4.0"))
+#define PCF8574_LIB_VERSION         (F("0.4.1"))
 
 #ifndef PCF8574_INITIAL_VALUE
 #define PCF8574_INITIAL_VALUE       0xFF
@@ -50,7 +50,7 @@ class PCF8574
 
 
   //  added 0.1.07/08 Septillion
-  uint8_t readButton8()  { return PCF8574::readButton8(_buttonMask); }
+  uint8_t readButton8() { return PCF8574::readButton8(_buttonMask); }
   uint8_t readButton8(const uint8_t mask);
   uint8_t readButton(const uint8_t pin);
   void    setButtonMask(const uint8_t mask) { _buttonMask = mask; };
diff --git a/README.md b/README.md
index 8609213..f6b379b 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@
 
 # PCF8574
 
-Arduino library for PCF8574 - 8 channel I2C IO expander
+Arduino library for PCF8574 - 8 channel I2C IO expander.
 
 
 ## Description
@@ -36,17 +36,52 @@ The library allows to read and write both single pins or 8 pins at once.
 Furthermore some additional functions are implemented that are playful and useful.
 
 
-#### Interrupts
+#### Interrupts intro
 
 The PCF8574 has an interrupt output line (INT) to notify an MCU that one of the input lines has changed.
 This can be used to prevent active polling of the PCF8574, which can be more efficient.
 
+From the datasheet:
+
+_An interrupt is generated by any rising or falling edge of the port inputs in the input mode. 
+After time, (Tiv), INT is valid. Resetting and reactivating the interrupt circuit is achieved 
+when data on the port is **changed to the original setting** or data is **read from**, or 
+**written to**, the port that generated the interrupt. 
+Resetting occurs in the read mode at the acknowledge bit after the rising edge of the SCL signal, 
+or in the write mode at the acknowledge bit after the high-to-low transition of the SCL signal._
+
+So there are three scenarios how the INT is reset.
+
+1. pins revert to original state (lesser known).
+2. read from the device (well known)
+3. write to the device (well known)
+
+This implies that polling the PCF8574 can miss an INT in scenario 1. (see #48)
+In practice if you have faster polling than your signals changes this would not
+be a problem. E.g. tactile switches and a polling frequency > 100 Hz will work.
+
+
+#### Interrupts library
+
 The library cannot handle the PCF8574 interrupts as it has no code for it. 
-The user should catch the interrupt in his own code and can use the library to see which line has changed.
+The user should catch the interrupt in his own code to set a flag and can use 
+the library to see which line has changed.
 
-There are two examples to show how interrupts can be used:
-- PCF8574_interrupt.ino
-- PCF8574_rotaryEncoder.ino
+There are two examples to show how interrupts can be handled:
+
+- **PCF8574_interrupt.ino**
+- **PCF8574_rotaryEncoder.ino**
+
+A more advanced interrupt handler would not set a boolean flag in the interrupt
+routine but increase a counter (uint8_t or larger). 
+Then it would be possible to see that:
+
+1. an interrupt occurred. (counter > 0)
+2. if one or more interrupts are not handled (counter > 1)
+
+A minimal example that shows catching missed interrupts:
+
+- **PCF8574_interrupt_advanced.ino**
 
 
 #### 0.4.0 Breaking change
@@ -194,7 +229,8 @@ It is advised to use pull-up or pull-down resistors so the lines have a defined
 
 #### Must
 
-- keep in sync with PCF8575
+- update documentation.
+- keep in sync with PCF8575  (as far as meaningful)
 
 #### Should
 
@@ -214,3 +250,4 @@ donate through PayPal or GitHub sponsors.
 
 Thank you,
 
+
diff --git a/examples/PCF8574_Wire1/.arduino-ci.yml b/examples/PCF8574_Wire1/.arduino-ci.yml
new file mode 100644
index 0000000..4297bcf
--- /dev/null
+++ b/examples/PCF8574_Wire1/.arduino-ci.yml
@@ -0,0 +1,27 @@
+platforms:
+  rpipico:
+    board: rp2040:rp2040:rpipico
+    package: rp2040:rp2040
+    gcc:
+      features:
+      defines:
+        - ARDUINO_ARCH_RP2040
+      warnings:
+      flags:
+
+packages:
+  rp2040:rp2040:
+    url: https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json
+
+compile:
+  # Choosing to run compilation tests on 2 different Arduino platforms
+  platforms:
+    # - uno
+    # - due
+    # - zero
+    # - leonardo
+    # - m4
+    - esp32
+    # - esp8266
+    # - mega2560
+    - rpipico
diff --git a/examples/PCF8574_Wire1/PCF8574_Wire1.ino b/examples/PCF8574_Wire1/PCF8574_Wire1.ino
new file mode 100644
index 0000000..9316c16
--- /dev/null
+++ b/examples/PCF8574_Wire1/PCF8574_Wire1.ino
@@ -0,0 +1,81 @@
+//
+//    FILE: PCF8574_Wire1.ino
+//  AUTHOR: Rob Tillaart
+//    DATE: 2016-04-30
+// PURPOSE: demo
+//     URL: https://github.com/RobTillaart/PCF8574
+
+
+#include "PCF8574.h"
+
+//  adjust addresses if needed
+PCF8574 PCF(0x39, &Wire1);
+
+
+void doHigh()
+{
+  PCF.write(4, HIGH);
+  int x = PCF.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
+void doLow()
+{
+  PCF.write(4, LOW);
+  int x = PCF.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
+void doToggle()
+{
+  PCF.toggle(4);
+  int x = PCF.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println(__FILE__);
+  Serial.print("PCF8574_LIB_VERSION:\t");
+  Serial.println(PCF8574_LIB_VERSION);
+
+  Wire1.begin();
+
+  if (!PCF.begin())
+  {
+    Serial.println("could not initialize...");
+  }
+  if (!PCF.isConnected())
+  {
+    Serial.println("=> not connected");
+    while(1);
+  }
+
+  int x = PCF.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+  delay(1000);
+}
+
+
+void loop()
+{
+  Serial.println("HLT");
+  while (Serial.available() == 0);
+  switch (Serial.read())
+  {
+    case 'H': doHigh(); break;
+    case 'L': doLow(); break;
+    case 'T': doToggle(); break;
+  }
+}
+
+
+//  -- END OF FILE --
diff --git a/examples/PCF8574_Wire2/.arduino-ci.yml b/examples/PCF8574_Wire2/.arduino-ci.yml
index 0b42078..59aad72 100644
--- a/examples/PCF8574_Wire2/.arduino-ci.yml
+++ b/examples/PCF8574_Wire2/.arduino-ci.yml
@@ -1,9 +1,27 @@
+platforms:
+  rpipico:
+    board: rp2040:rp2040:rpipico
+    package: rp2040:rp2040
+    gcc:
+      features:
+      defines:
+        - ARDUINO_ARCH_RP2040
+      warnings:
+      flags:
+
+packages:
+  rp2040:rp2040:
+    url: https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json
+
 compile:
   # Choosing to run compilation tests on 2 different Arduino platforms
   platforms:
-    # example made for Teensy a.o.
-    #
     # - uno
-    # - leonardo
     # - due
     # - zero
+    # - leonardo
+    # - m4
+    # - esp32
+    # - esp8266
+    # - mega2560
+    # - rpipico
diff --git a/examples/PCF8574_Wire2/PCF8574_Wire2.ino b/examples/PCF8574_Wire2/PCF8574_Wire2.ino
index 3013269..4d31e5e 100644
--- a/examples/PCF8574_Wire2/PCF8574_Wire2.ino
+++ b/examples/PCF8574_Wire2/PCF8574_Wire2.ino
@@ -1,14 +1,42 @@
-//
+ //
 //    FILE: PCF8574_Wire2.ino
 //  AUTHOR: Rob Tillaart
 //    DATE: 2016-04-30
 // PURPOSE: demo
+//     URL: https://github.com/RobTillaart/PCF8574
 
 
 #include "PCF8574.h"
 
 //  adjust addresses if needed
-PCF8574 PCF(0x39, &Wire2);
+PCF8574 PCF(0x39, &Wire2);  //  Wire2 ==> Teensy 
+
+
+void doHigh()
+{
+  PCF.write(4, HIGH);
+  int x = PCF.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
+void doLow()
+{
+  PCF.write(4, LOW);
+  int x = PCF.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
+void doToggle()
+{
+  PCF.toggle(4);
+  int x = PCF.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
 
 
 void setup()
@@ -50,32 +78,4 @@ void loop()
 }
 
 
-void doHigh()
-{
-  PCF.write(4, HIGH);
-  int x = PCF.read8();
-  Serial.print("Read ");
-  Serial.println(x, HEX);
-}
-
-
-void doLow()
-{
-  PCF.write(4, LOW);
-  int x = PCF.read8();
-  Serial.print("Read ");
-  Serial.println(x, HEX);
-}
-
-
-void doToggle()
-{
-  PCF.toggle(4);
-  int x = PCF.read8();
-  Serial.print("Read ");
-  Serial.println(x, HEX);
-}
-
-
 //  -- END OF FILE --
-
diff --git a/examples/PCF8574_interrupt/PCF8574_interrupt.ino b/examples/PCF8574_interrupt/PCF8574_interrupt.ino
index abe11e7..913805c 100644
--- a/examples/PCF8574_interrupt/PCF8574_interrupt.ino
+++ b/examples/PCF8574_interrupt/PCF8574_interrupt.ino
@@ -3,6 +3,7 @@
 //  AUTHOR: Rob Tillaart
 //    DATE: 2020-12-07
 // PURPOSE: test PCF8574 library
+//     URL: https://github.com/RobTillaart/PCF8574
 //
 // TEST SETUP
 //   Connect INT pin of the PCF8574 to UNO pin 2
diff --git a/examples/PCF8574_interrupt_advanced/PCF8574_interrupt_advanced.ino b/examples/PCF8574_interrupt_advanced/PCF8574_interrupt_advanced.ino
new file mode 100644
index 0000000..b435a52
--- /dev/null
+++ b/examples/PCF8574_interrupt_advanced/PCF8574_interrupt_advanced.ino
@@ -0,0 +1,86 @@
+//
+//    FILE: PCF8574_interrupt_advanced.ino
+//  AUTHOR: Rob Tillaart
+//    DATE: 2024-01-08
+// PURPOSE: test PCF8574 library
+//     URL: https://github.com/RobTillaart/PCF8574
+//
+//  TEST SETUP
+//   Connect INT pin of the PCF8574 to UNO pin 2
+//
+//   (from figure 4 datasheet
+//   Place a pull up resistor 4K7 between pin and 5V
+//   Place a capacitor 10-400 pF between pin and GND
+
+
+#include "PCF8574.h"
+
+PCF8574 PCF(0x38);
+
+
+////////////////////////////////////
+//
+//  INTERRUPT ROUTINE + FLAG
+//
+const int IRQPIN = 2;
+
+volatile uint8_t interruptCount = 0;
+
+void pcf_irq()
+{
+  interruptCount++;
+}
+
+
+////////////////////////////////////
+//
+//  MAIN CODE
+//
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println(__FILE__);
+  Serial.print("PCF8574_LIB_VERSION: ");
+  Serial.println(PCF8574_LIB_VERSION);
+
+  Wire.begin();
+  PCF.begin();
+
+  pinMode(IRQPIN, INPUT_PULLUP);
+  attachInterrupt(digitalPinToInterrupt(IRQPIN), pcf_irq, FALLING);
+}
+
+
+void loop()
+{
+  uint32_t now = millis();
+
+  //  make a local copy of the counter.
+  noInterrupts();
+  uint8_t irq_count = interruptCount;
+  interruptCount = 0;
+  interrupts();
+
+  if (irq_count > 0)
+  {
+    if (irq_count > 1)
+    {
+      Serial.print("IRQ missed: ");
+      Serial.println(irq_count - 1);  //  as last will be handled
+    }
+    int x = PCF.read8();
+    Serial.print("READ:\t");
+    Serial.print('\t');
+    Serial.print(now);
+    Serial.print('\t');
+    Serial.println(x, HEX);
+  }
+
+  //  simulate doing other things here.
+  //  uses to a large delay to miss IRQ's on purpose.
+  delay(1000);
+}
+
+
+//  -- END OF FILE --
+
diff --git a/examples/PCF8574_isConnected/PCF8574_isConnected.ino b/examples/PCF8574_isConnected/PCF8574_isConnected.ino
index 22a4566..3cbae9d 100644
--- a/examples/PCF8574_isConnected/PCF8574_isConnected.ino
+++ b/examples/PCF8574_isConnected/PCF8574_isConnected.ino
@@ -3,6 +3,7 @@
 //  AUTHOR: Rob Tillaart
 //    DATE: 2021-01-03
 // PURPOSE: demo isConnected function
+//     URL: https://github.com/RobTillaart/PCF8574
 
 
 #include "PCF8574.h"
diff --git a/examples/PCF8574_performance/PCF8574_performance.ino b/examples/PCF8574_performance/PCF8574_performance.ino
index 93fe865..fc5011f 100644
--- a/examples/PCF8574_performance/PCF8574_performance.ino
+++ b/examples/PCF8574_performance/PCF8574_performance.ino
@@ -3,6 +3,7 @@
 //  AUTHOR: Rob Tillaart
 //    DATE: 2021-01-24
 // PURPOSE: test PCF8574 library at different I2C speeds.
+//     URL: https://github.com/RobTillaart/PCF8574
 
 
 #include "PCF8574.h"
@@ -11,6 +12,8 @@ PCF8574 PCF(0x38);
 
 uint32_t start, stop;
 
+volatile uint8_t x;
+
 
 void setup()
 {
@@ -23,23 +26,31 @@ void setup()
 
   PCF.begin();
   Serial.println(PCF.isConnected());
+  delay(100);  //  time to flush Serial 
+
 
-  for (long clk = 100000; clk < 800000; clk += 100000)
+  for (long clk = 100000; clk < 800000; clk += 50000)
   {
-    Serial.println(clk);
+    //  setup and measure
     Wire.setClock(clk);
     start = micros();
-    int x = PCF.read8();
+    x = PCF.read8();
     stop = micros();
+
+    //  output results
+    Serial.println(clk);
     Serial.print("Read:\t");
     Serial.print(stop - start);
     Serial.print("\t");
     Serial.println(x);             //  keep build CI compiler happy
     delay(1000);
 
+    //  measure
     start = micros();
     PCF.write8(0xFF);
     stop = micros();
+
+    //  output results
     Serial.print("Write:\t ");
     Serial.println(stop - start);
     delay(1000);
@@ -53,3 +64,4 @@ void loop()
 
 
 //  -- END OF FILE --
+
diff --git a/examples/PCF8574_rotaryEncoder/PCF8574_rotaryEncoder.ino b/examples/PCF8574_rotaryEncoder/PCF8574_rotaryEncoder.ino
index 2051b3e..4320325 100644
--- a/examples/PCF8574_rotaryEncoder/PCF8574_rotaryEncoder.ino
+++ b/examples/PCF8574_rotaryEncoder/PCF8574_rotaryEncoder.ino
@@ -3,6 +3,7 @@
 //  AUTHOR: Rob Tillaart
 //    DATE: 2021-05-08
 // PURPOSE: demo PCF8574 as rotary encoder reader.
+//     URL: https://github.com/RobTillaart/PCF8574
 //
 //
 //  RotaryEncoder    PCF8574      UNO
@@ -30,13 +31,69 @@ int32_t encoder[4] = {0, 0, 0, 0};
 volatile bool flag = false;
 
 
+////////////////////////////////////////////////
+//
 //  IRQ routine
+//
 void moved()
 {
   flag = true;
 }
 
 
+////////////////////////////////////////////////
+//
+//  rotary routines
+//
+void initRotaryDecoder()
+{
+  uint8_t val = decoder.read8();
+  for (uint8_t i = 0; i < 4; i++)
+  {
+    lastpos[i] = val & 0x03;
+    val >>= 2;
+  }
+}
+
+
+//  assumes 4 rotary encoders connected to one PCF8574
+void updateRotaryDecoder()
+{
+  uint8_t val = decoder.read8();
+
+  //  check which of 4 has changed
+  for (uint8_t i = 0; i < 4; i++)
+  {
+    uint8_t currentpos = (val & 0x03);
+    if (lastpos[i] != currentpos)     //  moved!
+    {
+      uint8_t change = (lastpos[i] << 2) | currentpos;
+      switch (change)
+      {
+        case 0b0001:  //  fall through..
+        case 0b0111:
+        case 0b1110:
+        case 0b1000:
+          encoder[i]++;
+          break;
+        case 0b0010:
+        case 0b0100:
+        case 0b1101:
+        case 0b1011:
+          encoder[i]--;
+          break;
+      }
+      lastpos[i] = currentpos;
+    }
+    val >>= 2;
+  }
+}
+
+
+////////////////////////////////////////////////
+//
+//  main code
+//
 void setup()
 {
   Serial.begin(115200);
@@ -86,50 +143,5 @@ void loop()
 }
 
 
-void initRotaryDecoder()
-{
-  uint8_t val = decoder.read8();
-  for (uint8_t i = 0; i < 4; i++)
-  {
-    lastpos[i] = val & 0x03;
-    val >>= 2;
-  }
-}
-
-
-//  assumes 4 rotary encoders connected to one PCF8574
-void updateRotaryDecoder()
-{
-  uint8_t val = decoder.read8();
-
-  //  check which of 4 has changed
-  for (uint8_t i = 0; i < 4; i++)
-  {
-    uint8_t currentpos = (val & 0x03);
-    if (lastpos[i] != currentpos)     //  moved!
-    {
-      uint8_t change = (lastpos[i] << 2) | currentpos;
-      switch (change)
-      {
-        case 0b0001:  //  fall through..
-        case 0b0111:
-        case 0b1110:
-        case 0b1000:
-          encoder[i]++;
-          break;
-        case 0b0010:
-        case 0b0100:
-        case 0b1101:
-        case 0b1011:
-          encoder[i]--;
-          break;
-      }
-      lastpos[i] = currentpos;
-    }
-    val >>= 2;
-  }
-}
-
-
 //  -- END OF FILE --
 
diff --git a/examples/PCF8574_select/PCF8574_select.ino b/examples/PCF8574_select/PCF8574_select.ino
index d06d8a2..7cc593f 100644
--- a/examples/PCF8574_select/PCF8574_select.ino
+++ b/examples/PCF8574_select/PCF8574_select.ino
@@ -3,6 +3,7 @@
 //  AUTHOR: Rob Tillaart
 //    DATE: 2022-06-18
 // PURPOSE: demo PCF8574 library select functions
+//     URL: https://github.com/RobTillaart/PCF8574
 
 
 #include "PCF8574.h"
diff --git a/examples/PCF8574_test/PCF8574_test.ino b/examples/PCF8574_test/PCF8574_test.ino
index 3a7faf2..f1bf6cf 100644
--- a/examples/PCF8574_test/PCF8574_test.ino
+++ b/examples/PCF8574_test/PCF8574_test.ino
@@ -3,6 +3,7 @@
 //  AUTHOR: Rob Tillaart
 //    DATE: 7-febr-2013
 // PURPOSE: test PCF8574 library
+//     URL: https://github.com/RobTillaart/PCF8574
 
 
 #include "PCF8574.h"
@@ -10,6 +11,33 @@
 PCF8574 PCF_01(0x38);
 
 
+void doHigh()
+{
+  PCF_01.write(4, HIGH);
+  int x = PCF_01.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
+void doLow()
+{
+  PCF_01.write(4, LOW);
+  int x = PCF_01.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
+void doToggle()
+{
+  PCF_01.toggle(4);
+  int x = PCF_01.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
 void setup()
 {
   Serial.begin(115200);
@@ -41,32 +69,5 @@ void loop()
 }
 
 
-void doHigh()
-{
-  PCF_01.write(4, HIGH);
-  int x = PCF_01.read8();
-  Serial.print("Read ");
-  Serial.println(x, HEX);
-}
-
-
-void doLow()
-{
-  PCF_01.write(4, LOW);
-  int x = PCF_01.read8();
-  Serial.print("Read ");
-  Serial.println(x, HEX);
-}
-
-
-void doToggle()
-{
-  PCF_01.toggle(4);
-  int x = PCF_01.read8();
-  Serial.print("Read ");
-  Serial.println(x, HEX);
-}
-
-
 //  -- END OF FILE --
 
diff --git a/examples/PCF8574_test1/PCF8574_test1.ino b/examples/PCF8574_test1/PCF8574_test1.ino
index b66a548..5b09757 100644
--- a/examples/PCF8574_test1/PCF8574_test1.ino
+++ b/examples/PCF8574_test1/PCF8574_test1.ino
@@ -3,6 +3,7 @@
 //  AUTHOR: Rob Tillaart
 //    DATE: 27-08-2013
 // PURPOSE: demo
+//     URL: https://github.com/RobTillaart/PCF8574
 
 
 #include "PCF8574.h"
diff --git a/examples/PCF8574_test2/PCF8574_test2.ino b/examples/PCF8574_test2/PCF8574_test2.ino
index fee99dc..3237741 100644
--- a/examples/PCF8574_test2/PCF8574_test2.ino
+++ b/examples/PCF8574_test2/PCF8574_test2.ino
@@ -3,6 +3,7 @@
 //  AUTHOR: Rob Tillaart
 //    DATE: 2016-04-30
 // PURPOSE: demo rotateLeft, rotateRight and toggleMask
+//     URL: https://github.com/RobTillaart/PCF8574
 
 
 #include "PCF8574.h"
diff --git a/examples/PCF8574_test_ESP32/PCF8574_test_ESP32.ino b/examples/PCF8574_test_ESP32/PCF8574_test_ESP32.ino
index acf7d62..d3611b7 100644
--- a/examples/PCF8574_test_ESP32/PCF8574_test_ESP32.ino
+++ b/examples/PCF8574_test_ESP32/PCF8574_test_ESP32.ino
@@ -3,6 +3,7 @@
 //  AUTHOR: Rob Tillaart
 //    DATE: 7-febr-2013
 // PURPOSE: test PCF8574 library
+//     URL: https://github.com/RobTillaart/PCF8574
 
 
 #include "PCF8574.h"
@@ -10,6 +11,33 @@
 PCF8574 PCF_01(0x38);
 
 
+void doHigh()
+{
+  PCF_01.write(4, HIGH);
+  int x = PCF_01.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
+void doLow()
+{
+  PCF_01.write(4, LOW);
+  int x = PCF_01.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
+void doToggle()
+{
+  PCF_01.toggle(4);
+  int x = PCF_01.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
 void setup()
 {
   Serial.begin(115200);
@@ -42,32 +70,5 @@ void loop()
 }
 
 
-void doHigh()
-{
-  PCF_01.write(4, HIGH);
-  int x = PCF_01.read8();
-  Serial.print("Read ");
-  Serial.println(x, HEX);
-}
-
-
-void doLow()
-{
-  PCF_01.write(4, LOW);
-  int x = PCF_01.read8();
-  Serial.print("Read ");
-  Serial.println(x, HEX);
-}
-
-
-void doToggle()
-{
-  PCF_01.toggle(4);
-  int x = PCF_01.read8();
-  Serial.print("Read ");
-  Serial.println(x, HEX);
-}
-
-
 //  -- END OF FILE --
 
diff --git a/examples/PCF8574_test_RP2040/PCF8574_test_RP2040.ino b/examples/PCF8574_test_RP2040/PCF8574_test_RP2040.ino
index d9e2d9e..6d3e635 100644
--- a/examples/PCF8574_test_RP2040/PCF8574_test_RP2040.ino
+++ b/examples/PCF8574_test_RP2040/PCF8574_test_RP2040.ino
@@ -3,6 +3,7 @@
 //  AUTHOR: Rob Tillaart
 //    DATE: 2023-12-10
 // PURPOSE: test PCF8574 library
+//     URL: https://github.com/RobTillaart/PCF8574
 
 
 #include "PCF8574.h"
@@ -10,6 +11,33 @@
 PCF8574 PCF_01(0x38);
 
 
+void doHigh()
+{
+  PCF_01.write(4, HIGH);
+  int x = PCF_01.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
+void doLow()
+{
+  PCF_01.write(4, LOW);
+  int x = PCF_01.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
+void doToggle()
+{
+  PCF_01.toggle(4);
+  int x = PCF_01.read8();
+  Serial.print("Read ");
+  Serial.println(x, HEX);
+}
+
+
 void setup()
 {
   Serial.begin(115200);
@@ -44,32 +72,5 @@ void loop()
 }
 
 
-void doHigh()
-{
-  PCF_01.write(4, HIGH);
-  int x = PCF_01.read8();
-  Serial.print("Read ");
-  Serial.println(x, HEX);
-}
-
-
-void doLow()
-{
-  PCF_01.write(4, LOW);
-  int x = PCF_01.read8();
-  Serial.print("Read ");
-  Serial.println(x, HEX);
-}
-
-
-void doToggle()
-{
-  PCF_01.toggle(4);
-  int x = PCF_01.read8();
-  Serial.print("Read ");
-  Serial.println(x, HEX);
-}
-
-
 //  -- END OF FILE --
 
diff --git a/library.json b/library.json
index 9ab5b51..fe12740 100644
--- a/library.json
+++ b/library.json
@@ -15,7 +15,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/PCF8574.git"
   },
-  "version": "0.4.0",
+  "version": "0.4.1",
   "license": "MIT",
   "frameworks": "*",
   "platforms": "*",
diff --git a/library.properties b/library.properties
index ca2edad..a1cc635 100644
--- a/library.properties
+++ b/library.properties
@@ -1,5 +1,5 @@
 name=PCF8574
-version=0.4.0
+version=0.4.1
 author=Rob Tillaart <rob.tillaart@gmail.com>
 maintainer=Rob Tillaart <rob.tillaart@gmail.com>
 sentence=Arduino library for PCF8574 - 8 channel I2C IO expander