diff --git a/Usb.cpp b/Usb.cpp
index 4f554c8b..c46ea5b3 100644
--- a/Usb.cpp
+++ b/Usb.cpp
@@ -426,7 +426,7 @@ void USB::Task(void) //USB state machine
 {
         uint8_t rcode;
         uint8_t tmpdata;
-        static unsigned long delay = 0;
+        static uint32_t delay = 0;
         //USB_DEVICE_DESCRIPTOR buf;
         bool lowspeed = false;
 
diff --git a/cdcftdi.cpp b/cdcftdi.cpp
index 91f189d2..5d1688c8 100644
--- a/cdcftdi.cpp
+++ b/cdcftdi.cpp
@@ -290,8 +290,8 @@ uint8_t FTDI::SetBaudRate(uint32_t baud) {
                         if(divisor3 != 0) baud_value |= 0x8000; // 0.25
                 if(baud_value == 1) baud_value = 0; /* special case for maximum baud rate */
         } else {
-                static const unsigned char divfrac [8] = {0, 3, 2, 0, 1, 1, 2, 3};
-                static const unsigned char divindex[8] = {0, 0, 0, 1, 0, 1, 1, 1};
+                static const uint8_t divfrac [8] = {0, 3, 2, 0, 1, 1, 2, 3};
+                static const uint8_t divindex[8] = {0, 0, 0, 1, 0, 1, 1, 1};
 
                 baud_value = divisor3 >> 3;
                 baud_value |= divfrac [divisor3 & 0x7] << 14;
diff --git a/examples/USBH_MIDI/USBH_MIDI_dump/USBH_MIDI_dump.ino b/examples/USBH_MIDI/USBH_MIDI_dump/USBH_MIDI_dump.ino
index 524447f3..08428381 100644
--- a/examples/USBH_MIDI/USBH_MIDI_dump/USBH_MIDI_dump.ino
+++ b/examples/USBH_MIDI/USBH_MIDI_dump/USBH_MIDI_dump.ino
@@ -24,7 +24,7 @@ USB Usb;
 USBH_MIDI  Midi(&Usb);
 
 void MIDI_poll();
-void doDelay(unsigned long t1, unsigned long t2, unsigned long delayTime);
+void doDelay(uint32_t t1, uint32_t t2, uint32_t delayTime);
 
 boolean bFirst;
 uint16_t pid, vid;
@@ -77,9 +77,9 @@ void MIDI_poll()
 }
 
 // Delay time (max 16383 us)
-void doDelay(unsigned long t1, unsigned long t2, unsigned long delayTime)
+void doDelay(uint32_t t1, uint32_t t2, uint32_t delayTime)
 {
-  unsigned long t3;
+  uint32_t t3;
 
   if ( t1 > t2 ) {
     t3 = (0xFFFFFFFF - t1 + t2);
diff --git a/examples/USBH_MIDI/USB_MIDI_converter/USB_MIDI_converter.ino b/examples/USBH_MIDI/USB_MIDI_converter/USB_MIDI_converter.ino
index ddc803dd..32bd4cc5 100644
--- a/examples/USBH_MIDI/USB_MIDI_converter/USB_MIDI_converter.ino
+++ b/examples/USBH_MIDI/USB_MIDI_converter/USB_MIDI_converter.ino
@@ -35,7 +35,7 @@ USB Usb;
 USBH_MIDI  Midi(&Usb);
 
 void MIDI_poll();
-void doDelay(unsigned long t1, unsigned long t2, unsigned long delayTime);
+void doDelay(uint32_t t1, uint32_t t2, uint32_t delayTime);
 
 void setup()
 {
@@ -73,9 +73,9 @@ void MIDI_poll()
 }
 
 // Delay time (max 16383 us)
-void doDelay(unsigned long t1, unsigned long t2, unsigned long delayTime)
+void doDelay(uint32_t t1, uint32_t t2, uint32_t delayTime)
 {
-  unsigned long t3;
+  uint32_t t3;
 
   if ( t1 > t2 ) {
     t3 = (0xFFFFFFFF - t1 + t2);
diff --git a/examples/USBH_MIDI/USB_MIDI_converter_multi/USB_MIDI_converter_multi.ino b/examples/USBH_MIDI/USB_MIDI_converter_multi/USB_MIDI_converter_multi.ino
index 76421ca4..a118e7a9 100644
--- a/examples/USBH_MIDI/USB_MIDI_converter_multi/USB_MIDI_converter_multi.ino
+++ b/examples/USBH_MIDI/USB_MIDI_converter_multi/USB_MIDI_converter_multi.ino
@@ -37,7 +37,7 @@ USBH_MIDI  Midi1(&Usb);
 USBH_MIDI  Midi2(&Usb);
 
 void MIDI_poll();
-void doDelay(unsigned long t1, unsigned long t2, unsigned long delayTime);
+void doDelay(uint32_t t1, uint32_t t2, uint32_t delayTime);
 
 void setup()
 {
@@ -81,9 +81,9 @@ void MIDI_poll()
 }
 
 // Delay time (max 16383 us)
-void doDelay(unsigned long t1, unsigned long t2, unsigned long delayTime)
+void doDelay(uint32_t t1, uint32_t t2, uint32_t delayTime)
 {
-  unsigned long t3;
+  uint32_t t3;
 
   if ( t1 > t2 ) {
     t3 = (0xFFFFFFFF - t1 + t2);
diff --git a/examples/USBH_MIDI/bidrectional_converter/bidrectional_converter.ino b/examples/USBH_MIDI/bidrectional_converter/bidrectional_converter.ino
index ce1efc4f..99b486fd 100644
--- a/examples/USBH_MIDI/bidrectional_converter/bidrectional_converter.ino
+++ b/examples/USBH_MIDI/bidrectional_converter/bidrectional_converter.ino
@@ -43,7 +43,7 @@ USB Usb;
 USBH_MIDI Midi(&Usb);
 
 void MIDI_poll();
-void doDelay(unsigned long t1, unsigned long t2, unsigned long delayTime);
+void doDelay(uint32_t t1, uint32_t t2, uint32_t delayTime);
 
 //If you want handle System Exclusive message, enable this #define otherwise comment out it.
 #define USBH_MIDI_SYSEX_ENABLE
@@ -149,9 +149,9 @@ void MIDI_poll()
 }
 
 // Delay time (max 16383 us)
-void doDelay(unsigned long t1, unsigned long t2, unsigned long delayTime)
+void doDelay(uint32_t t1, uint32_t t2, uint32_t delayTime)
 {
-  unsigned long t3;
+  uint32_t t3;
 
   if ( t1 > t2 ) {
     t3 = (0xFFFFFFFF - t1 + t2);
diff --git a/examples/USB_desc/USB_desc.ino b/examples/USB_desc/USB_desc.ino
index dd9c5b22..cda8505c 100644
--- a/examples/USB_desc/USB_desc.ino
+++ b/examples/USB_desc/USB_desc.ino
@@ -60,14 +60,14 @@ void setup()
   delay( 200 );
 }
 
-byte getdevdescr( byte addr, byte &num_conf );
+uint8_t getdevdescr( uint8_t addr, uint8_t &num_conf );
 
 void PrintDescriptors(uint8_t addr)
 {
   uint8_t rcode = 0;
-  byte num_conf = 0;
+  uint8_t num_conf = 0;
 
-  rcode = getdevdescr( (byte)addr, num_conf );
+  rcode = getdevdescr( (uint8_t)addr, num_conf );
   if ( rcode )
   {
     printProgStr(Gen_Error_str);
@@ -108,10 +108,10 @@ void loop()
   }
 }
 
-byte getdevdescr( byte addr, byte &num_conf )
+uint8_t getdevdescr( uint8_t addr, uint8_t &num_conf )
 {
   USB_DEVICE_DESCRIPTOR buf;
-  byte rcode;
+  uint8_t rcode;
   rcode = Usb.getDevDescr( addr, 0, 0x12, ( uint8_t *)&buf );
   if ( rcode ) {
     return ( rcode );
@@ -195,14 +195,14 @@ void printhubdescr(uint8_t *descrptr, uint8_t addr)
   //    PrintHubPortStatus(&Usb, addr, i, 1);
 }
 
-byte getconfdescr( byte addr, byte conf )
+uint8_t getconfdescr( uint8_t addr, uint8_t conf )
 {
   uint8_t buf[ BUFSIZE ];
   uint8_t* buf_ptr = buf;
-  byte rcode;
-  byte descr_length;
-  byte descr_type;
-  unsigned int total_length;
+  uint8_t rcode;
+  uint8_t descr_length;
+  uint8_t descr_type;
+  uint16_t total_length;
   rcode = Usb.getConfDescr( addr, 0, 4, conf, buf );  //get total length
   LOBYTE( total_length ) = buf[ 2 ];
   HIBYTE( total_length ) = buf[ 3 ];
@@ -316,8 +316,8 @@ void printepdescr( uint8_t* descr_ptr )
 /*function to print unknown descriptor */
 void printunkdescr( uint8_t* descr_ptr )
 {
-  byte length = *descr_ptr;
-  byte i;
+  uint8_t length = *descr_ptr;
+  uint8_t i;
   printProgStr(Unk_Header_str);
   printProgStr(Unk_Length_str);
   print_hex( *descr_ptr, 8 );
diff --git a/examples/pl2303/pl2303_tinygps/pl2303_tinygps.ino b/examples/pl2303/pl2303_tinygps/pl2303_tinygps.ino
index cc5ef4de..d6c79895 100644
--- a/examples/pl2303/pl2303_tinygps/pl2303_tinygps.ino
+++ b/examples/pl2303/pl2303_tinygps/pl2303_tinygps.ino
@@ -130,7 +130,7 @@ void printFloat(double number, int digits)
   number += rounding;
 
   // Extract the integer part of the number and print it
-  unsigned long int_part = (unsigned long)number;
+  uint32_t int_part = (uint32_t)number;
   double remainder = number - (double)int_part;
   Serial.print(int_part);
 
@@ -150,12 +150,12 @@ void printFloat(double number, int digits)
 
 void gpsdump(TinyGPS &gps)
 {
-  long lat, lon;
+  int32_t lat, lon;
   float flat, flon;
-  unsigned long age, date, time, chars;
+  uint32_t age, date, time, chars;
   int year;
   byte month, day, hour, minute, second, hundredths;
-  unsigned short sentences, failed;
+  uint16_t sentences, failed;
 
   gps.get_position(&lat, &lon, &age);
   Serial.print("Lat/Long(10^-5 deg): "); Serial.print(lat); Serial.print(", "); Serial.print(lon);
diff --git a/usbh_midi.cpp b/usbh_midi.cpp
index 54231387..945c7c68 100644
--- a/usbh_midi.cpp
+++ b/usbh_midi.cpp
@@ -243,9 +243,9 @@ void USBH_MIDI::parseConfigDescr( uint8_t addr, uint8_t conf )
         uint8_t rcode;
         uint8_t descr_length;
         uint8_t descr_type;
-        unsigned int total_length;
+        uint16_t total_length;
         USB_ENDPOINT_DESCRIPTOR *epDesc;
-        boolean isMidi = false;
+        bool isMidi = false;
 
         // get configuration descriptor (get descriptor size only)
         rcode = pUsb->getConfDescr( addr, 0, 4, conf, buf );
@@ -486,9 +486,9 @@ uint8_t USBH_MIDI::lookupMsgSize(uint8_t midiMsg)
 }
 
 /* SysEx data size counter */
-unsigned int USBH_MIDI::countSysExDataSize(uint8_t *dataptr)
+uint16_t USBH_MIDI::countSysExDataSize(uint8_t *dataptr)
 {
-        unsigned int c = 1;
+        uint16_t c = 1;
 
         if( *dataptr != 0xf0 ){ //not SysEx
                 return 0;
@@ -510,12 +510,12 @@ unsigned int USBH_MIDI::countSysExDataSize(uint8_t *dataptr)
 }
 
 /* Send SysEx message to MIDI device */
-uint8_t USBH_MIDI::SendSysEx(uint8_t *dataptr, unsigned int datasize, uint8_t nCable)
+uint8_t USBH_MIDI::SendSysEx(uint8_t *dataptr, uint16_t datasize, uint8_t nCable)
 {
         uint8_t buf[64];
         uint8_t rc;
-        unsigned int n = datasize;
-        unsigned int pktSize = (n*10/3+7)/10*4;   //Calculate total USB MIDI packet size
+        uint16_t n = datasize;
+        uint16_t pktSize = (n*10/3+7)/10*4;   //Calculate total USB MIDI packet size
         uint8_t wptr = 0;
         uint8_t maxpkt = epInfo[epDataInIndex].maxPktSize;
 
diff --git a/usbh_midi.h b/usbh_midi.h
index 70973d0a..f689ea11 100644
--- a/usbh_midi.h
+++ b/usbh_midi.h
@@ -58,7 +58,7 @@ protected:
         uint8_t readPtr;
 
         void parseConfigDescr(uint8_t addr, uint8_t conf);
-        unsigned int countSysExDataSize(uint8_t *dataptr);
+        uint16_t countSysExDataSize(uint8_t *dataptr);
 #ifdef DEBUG_USB_HOST
         void PrintEndpointDescriptor( const USB_ENDPOINT_DESCRIPTOR* ep_ptr );
 #endif
@@ -70,7 +70,7 @@ public:
         uint8_t RecvData(uint8_t *outBuf);
         uint8_t SendData(uint8_t *dataptr, uint8_t nCable=0);
         uint8_t lookupMsgSize(uint8_t midiMsg);
-        uint8_t SendSysEx(uint8_t *dataptr, unsigned int datasize, uint8_t nCable=0);
+        uint8_t SendSysEx(uint8_t *dataptr, uint16_t datasize, uint8_t nCable=0);
         uint8_t SendRawData(uint16_t bytes_send, uint8_t *dataptr);
         // backward compatibility functions
         inline uint8_t RcvData(uint16_t *bytes_rcvd, uint8_t *dataptr){ return RecvData(bytes_rcvd, dataptr); };