Generic SSD1306 display support for ESP32 added (#1847)

* add oled support for esp32_rtl433

* add generic ssd1306 usage into documentation

* remove additiona environment with the oled

---------

Co-authored-by: Jouni Paulus <paulus@nuppu.eternal>

docs/use/displays.md

@@ -1,6 +1,6 @@
 # Displays
 
-## SSD1306 Display (Heltec SX127X and LILYGO® LoRa32 boards)
+## SSD1306 Display (Heltec SX127X, LILYGO® LoRa32 boards, generic SSD1306 displays)
 Several options are available for the display of information on the SSD1306 display. Some options are exclusive to each other, and when a different option is enabled, the current option is disabled.
 
 The current SSD1306 display states are being published to the `SSD1306toMQTT` topic, e.g.
@@ -106,3 +106,39 @@ If you want to load the default configuration use the command:
 `mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoSSD1306/config -m '{"init":true}'`
 
 Note that this will not change the stored configuration, `erase` or `save` is still needed to overwrite the saved configuration.
+
+### Connecting a generic SSD1306 display to ESP32
+It is possible to connect a generic SSD1306 display with resolution 128*64 to the hardware setups.
+This example describes how to do it with the ESP32 board.
+- Connect the display to the ESP32 (display → ESP32):
+  - VCC → 5V (or 3.3V, check your display documentation)
+  - GND → GND
+  - SCL → pin 22
+  - SDA → pin 21
+- Modify the environment definition in `environments.ini`.
+  - Add the display library:
+    ```
+    lib_deps =
+      ${com-esp32.lib_deps}
+      ...
+      ${libraries.ssd1306}
+    ```
+  - Add relevant build flags:
+    ```
+    build_flags =
+      ${com-esp32.build_flags}
+      ...
+    ; *** Generic SSD1306 OLED Options **
+      '-DZdisplaySSD1306="GenericSSD1306"'
+      '-DOLED_SDA=21'               ; SSD1306 pin SDA
+      '-DOLED_SCL=22'               ; SSD1306 pin SCL
+      '-DGenericSSD1306=true'
+      '-DJSON_TO_OLED=true'
+      '-DDISPLAY_PAGE_INTERVAL=30'
+    ;  '-DLOG_TO_OLED=true'         ; Enable log to OLED
+    ;  '-DLOG_LEVEL_OLED=LOG_LEVEL_NOTICE'
+    ;  '-DDISPLAY_IDLE_LOGO=false'
+    ;  '-DDISPLAY_BRIGHTNESS=80'
+    ;  '-DDISPLAY_METRIC=false'
+    ;  '-DDISPLAY_FLIP=false'
+    ```

main/ZdisplaySSD1306.ino

@@ -302,6 +302,8 @@ OledSerial::OledSerial(int x) {
   // delay(50);
   // digitalWrite(OLED_RST, HIGH);
   display = new SSD1306Wire(0x3c, OLED_SDA, OLED_SCL, GEOMETRY_128_64);
+#  elif defined(GenericSSD1306) // a generic ssd1306 oled with of size 128*64
+  display = new SSD1306Wire(0x3c, OLED_SDA, OLED_SCL, GEOMETRY_128_64);
 #  endif
 }