diff --git a/README.md b/README.md
index 98ad975..d6ac766 100644
--- a/README.md
+++ b/README.md
@@ -125,9 +125,11 @@ or for the SH1106:
 #include <SPI.h>
 #include "SH1106Spi.h"
 
-SH1106Spi display(D0, D2);  // RES, DC
+SH1106Spi display(D0, D2, CS);  // RES, DC, CS
 ```
 
+In case the CS pin is not used (hard wired to ground), pass CS as -1.
+
 ## API
 
 ### Display Control
diff --git a/library.json b/library.json
index 18f59fd..0c09cab 100644
--- a/library.json
+++ b/library.json
@@ -1,6 +1,6 @@
 {
   "name": "ESP8266 and ESP32 OLED driver for SSD1306 displays",
-  "version": "4.3.0",
+  "version": "4.4.0",
   "keywords": "ssd1306, oled, display, i2c",
   "description": "I2C display driver for SSD1306 OLED displays connected to ESP8266, ESP32, Mbed-OS",
   "license": "MIT",
diff --git a/library.properties b/library.properties
index 42fb10a..5e289cc 100644
--- a/library.properties
+++ b/library.properties
@@ -1,5 +1,5 @@
 name=ESP8266 and ESP32 OLED driver for SSD1306 displays
-version=4.3.0
+version=4.4.0
 author=ThingPulse, Fabrice Weinberg
 maintainer=ThingPulse <info@thingpulse.com>
 sentence=I2C display driver for SSD1306 OLED displays connected to ESP8266, ESP32, Mbed-OS
diff --git a/src/SH1106Spi.h b/src/SH1106Spi.h
index b31dd84..2862e9f 100644
--- a/src/SH1106Spi.h
+++ b/src/SH1106Spi.h
@@ -41,6 +41,7 @@ class SH1106Spi : public OLEDDisplay {
       uint8_t             _cs;
 
   public:
+    /* pass _cs as -1 to indicate "do not use CS pin", for cases where it is hard wired low */
     SH1106Spi(uint8_t _rst, uint8_t _dc, uint8_t _cs, OLEDDISPLAY_GEOMETRY g = GEOMETRY_128_64) {
         setGeometry(g);
 
@@ -51,7 +52,9 @@ class SH1106Spi : public OLEDDisplay {
 
     bool connect(){
       pinMode(_dc, OUTPUT);
-      pinMode(_cs, OUTPUT);
+      if (_cs != (uint8_t) -1) {
+        pinMode(_cs, OUTPUT);
+      }  
       pinMode(_rst, OUTPUT);
 
       SPI.begin ();
@@ -105,13 +108,13 @@ class SH1106Spi : public OLEDDisplay {
          sendCommand(0xB0 + y);
          sendCommand(minBoundXp2H);
          sendCommand(minBoundXp2L);
-         digitalWrite(_cs, HIGH);
+         set_CS(HIGH);
          digitalWrite(_dc, HIGH);   // data mode
-         digitalWrite(_cs, LOW);
+         set_CS(LOW);
          for (x = minBoundX; x <= maxBoundX; x++) {
            SPI.transfer(buffer[x + y * displayWidth]);
          }
-         digitalWrite(_cs, HIGH);
+         set_CS(HIGH);
          yield();
        }
      #else
@@ -119,13 +122,13 @@ class SH1106Spi : public OLEDDisplay {
         sendCommand(0xB0 + y);
         sendCommand(0x02);
         sendCommand(0x10);
-        digitalWrite(_cs, HIGH);
+        set_CS(HIGH);
         digitalWrite(_dc, HIGH);   // data mode
-        digitalWrite(_cs, LOW);
+        set_CS(LOW);
         for( uint8_t x=0; x < displayWidth; x++) {
           SPI.transfer(buffer[x + y * displayWidth]);
         }
-        digitalWrite(_cs, HIGH);
+        set_CS(HIGH);
         yield();
       }
      #endif
@@ -135,12 +138,17 @@ class SH1106Spi : public OLEDDisplay {
 	int getBufferOffset(void) {
 		return 0;
 	}
+    inline void set_CS(bool level) {
+      if (_cs != (uint8_t) -1) {
+        digitalWrite(_cs, level);
+      }
+    };
     inline void sendCommand(uint8_t com) __attribute__((always_inline)){
-      digitalWrite(_cs, HIGH);
+      set_CS(HIGH);
       digitalWrite(_dc, LOW);
-      digitalWrite(_cs, LOW);
+      set_CS(LOW);
       SPI.transfer(com);
-      digitalWrite(_cs, HIGH);
+      set_CS(HIGH);
     }
 };
 
diff --git a/src/SSD1306Spi.h b/src/SSD1306Spi.h
index 08cb4a8..b8d7b78 100644
--- a/src/SSD1306Spi.h
+++ b/src/SSD1306Spi.h
@@ -47,6 +47,7 @@ class SSD1306Spi : public OLEDDisplay {
       uint8_t             _cs;
 
   public:
+    /* pass _cs as -1 to indicate "do not use CS pin", for cases where it is hard wired low */
     SSD1306Spi(uint8_t _rst, uint8_t _dc, uint8_t _cs, OLEDDISPLAY_GEOMETRY g = GEOMETRY_128_64) {
         setGeometry(g);
 
@@ -57,7 +58,9 @@ class SSD1306Spi : public OLEDDisplay {
 
     bool connect(){
       pinMode(_dc, OUTPUT);
-      pinMode(_cs, OUTPUT);
+      if (_cs != (uint8_t) -1) {
+        pinMode(_cs, OUTPUT);
+      }  
       pinMode(_rst, OUTPUT);
 
       SPI.begin ();
@@ -111,16 +114,16 @@ class SSD1306Spi : public OLEDDisplay {
        sendCommand(minBoundY);
        sendCommand(maxBoundY);
 
-       digitalWrite(_cs, HIGH);
+       set_CS(HIGH);
        digitalWrite(_dc, HIGH);   // data mode
-       digitalWrite(_cs, LOW);
+       set_CS(LOW);
        for (y = minBoundY; y <= maxBoundY; y++) {
          for (x = minBoundX; x <= maxBoundX; x++) {
            SPI.transfer(buffer[x + y * displayWidth]);
          }
          yield();
        }
-       digitalWrite(_cs, HIGH);
+       set_CS(HIGH);
      #else
        // No double buffering
        sendCommand(COLUMNADDR);
@@ -136,14 +139,14 @@ class SSD1306Spi : public OLEDDisplay {
          sendCommand(0x3);
        }
 
-        digitalWrite(_cs, HIGH);
+        set_CS(HIGH);
         digitalWrite(_dc, HIGH);   // data mode
-        digitalWrite(_cs, LOW);
+        set_CS(LOW);
         for (uint16_t i=0; i<displayBufferSize; i++) {
           SPI.transfer(buffer[i]);
           yield();
         }
-        digitalWrite(_cs, HIGH);
+        set_CS(HIGH);
      #endif
     }
 
@@ -151,12 +154,17 @@ class SSD1306Spi : public OLEDDisplay {
 	int getBufferOffset(void) {
 		return 0;
 	}
+    inline void set_CS(bool level) {
+      if (_cs != (uint8_t) -1) {
+        digitalWrite(_cs, level);
+      }
+    };
     inline void sendCommand(uint8_t com) __attribute__((always_inline)){
-      digitalWrite(_cs, HIGH);
+      set_CS(HIGH);
       digitalWrite(_dc, LOW);
-      digitalWrite(_cs, LOW);
+      set_CS(LOW);
       SPI.transfer(com);
-      digitalWrite(_cs, HIGH);
+      set_CS(HIGH);
     }
 };
 
diff --git a/src/SSD1306Wire.h b/src/SSD1306Wire.h
index 9df32d1..d8beec4 100644
--- a/src/SSD1306Wire.h
+++ b/src/SSD1306Wire.h
@@ -39,6 +39,11 @@
 #define _min	min
 #define _max	max
 #endif
+#if defined(ARDUINO_ARCH_ESP32)
+#define I2C_MAX_TRANSFER_BYTE 128 /** ESP32 can Transfer 128 bytes */
+#else
+#define I2C_MAX_TRANSFER_BYTE 17
+#endif
 //--------------------------------------
 
 class SSD1306Wire : public OLEDDisplay {
@@ -147,7 +152,7 @@ class SSD1306Wire : public OLEDDisplay {
 
             _wire->write(buffer[x + y * this->width()]);
             k++;
-            if (k == 16)  {
+            if (k == (I2C_MAX_TRANSFER_BYTE - 1))  {
               _wire->endTransmission();
               k = 0;
             }
@@ -170,7 +175,7 @@ class SSD1306Wire : public OLEDDisplay {
         for (uint16_t i=0; i < displayBufferSize; i++) {
           _wire->beginTransmission(this->_address);
           _wire->write(0x40);
-          for (uint8_t x = 0; x < 16; x++) {
+          for (uint8_t x = 0; x < (I2C_MAX_TRANSFER_BYTE - 1); x++) {
             _wire->write(buffer[i]);
             i++;
           }