[Shelly1] Add first test build for Shelly1 nodes

[Shelly1 Open Source (ESP8266-2MB)](https://shelly.cloud/shelly1-open-source/)
This is a preliminary test version as I have not yet received my ordered modules.
Also there is a [feature request](esp8266/Arduino#5096 (comment)) out for adding proper flash layout for these 2M flash modules which allow proper OTA.

Author: TD-er

before_deploy

@@ -21,6 +21,7 @@ for ENV in \
   dev_ESP8266PUYA_1024\
   dev_ESP8266PUYA_1024_VCC\
   hard_SONOFF_POW\
+  hard_Shelly_1\
   esp32dev;\
 do
   echo

platformio.ini

@@ -66,12 +66,12 @@ platform                  = https://github.com/platformio/platform-espressif8266
 [core_esp32_0_12_0]
 platform                  = [email protected]
 
-[core_esp32_1_3_0]
-platform                  = [email protected]
-
 [core_esp32_1_2_0]
 platform                  = [email protected]
 
+[core_esp32_1_3_0]
+platform                  = [email protected]
+
 [core_esp32_stage]
 platform                  = https://github.com/platformio/platform-espressif32.git#feature/stage
 
@@ -176,6 +176,12 @@ board                     = esp_wroom_02
 build_unflags             = ${common.build_unflags}
 build_flags               = ${common.build_flags} -Wl,-Tesp8266.flash.2m.ld
 
+[esp8266_2M]
+board_build.flash_mode    = dio
+board_build.f_cpu         = ${common.board_build.f_cpu}
+build_unflags             = ${common.build_unflags}
+build_flags               = ${common.build_flags} -Wl,-Tesp8266.flash.2m.ld
+
 [esp8266_4M]
 board_build.flash_mode    = dio
 board_build.f_cpu         = ${common.board_build.f_cpu}
@@ -637,6 +643,25 @@ build_flags               = ${Sonoff.build_flags} -D PLUGIN_SET_SONOFF_POW_R2
 ;build_unflags             = ${Sonoff.build_unflags}
 ;build_flags               = ${Sonoff.build_flags} -D PLUGIN_SET_SONOFF_TOUCH
 
+; Shelly1 Open Source (ESP8266-2MB)
+; https://shelly.cloud/shelly1-open-source/
+; GPIO04 Relay (non inverted)
+; GPIO05 Button
+[env:hard_Shelly_1]
+upload_speed              = ${common.upload_speed}
+monitor_speed             = ${common.monitor_speed}
+framework                 = ${common.framework}
+platform                  = ${common.platform}
+lib_deps                  = ${common.lib_deps}
+lib_ignore                = ${common.lib_ignore}
+lib_ldf_mode              = ${common.lib_ldf_mode}
+lib_archive               = ${common.lib_archive}
+board_build.f_cpu         = ${esp8266_2M.board_build.f_cpu}
+board_build.flash_mode    = ${esp8266_2M.board_build.flash_mode}
+board                     = ${common.board}
+build_unflags             = ${esp8266_2M.build_unflags}
+build_flags               = ${esp8266_2M.build_flags} -D PLUGIN_SET_SHELLY_1
+
 
 
 ; LED Strips ; ****; ****; ****; ****; ****; ****;

src/define_plugin_sets.h

@@ -136,6 +136,18 @@ To create/register a plugin, you have to :
     #define PLUGIN_SET_ONLY_SWITCH
 #endif
 
+// Shelly ----------------------------
+#ifdef PLUGIN_SET_SHELLY_1
+    #define PLUGIN_SET_ONLY_SWITCH
+    #define CONTROLLER_SET_STABLE
+    #define NOTIFIER_SET_STABLE
+
+    #undef DEFAULT_PIN_I2C_SDA
+    #undef DEFAULT_PIN_I2C_SCL
+    #define DEFAULT_PIN_I2C_SDA    6  // GPIO4 conflicts with relay control.
+    #define DEFAULT_PIN_I2C_SCL    7  // GPIO5 conflicts with SW input
+#endif
+
 // Easy ----------------------------
 #ifdef PLUGIN_SET_EASY_TEMP
     #define PLUGIN_SET_ONLY_TEMP_HUM