addd ssd1306 lib

P1_gateway_FW/lib/esp8266-oled-ssd1306-4.2.0/UPGRADE-4.0.md

@@ -0,0 +1,27 @@
+# Upgrade from 3.x to 4.0
+
+There are changes that breaks compatibility with older versions.
+
+1. You'll have to change data type for all your binary resources such as images and fonts from
+    
+    ```c
+    const char MySymbol[] PROGMEM = {
+    ```
+    
+    to
+    
+    ```c
+    const uint8_t MySymbol[] PROGMEM = {
+    ```
+
+1. Arguments of `setContrast` from `char` to `uint8_t`
+    
+    ```c++
+    void OLEDDisplay::setContrast(char contrast, char precharge, char comdetect);
+    ```
+    
+    to
+    
+    ```c++
+    void OLEDDisplay::setContrast(uint8_t contrast, uint8_t precharge, uint8_t comdetect);
+    ```