I2C over Serial, preliminary stub (#22388)

* I2C over Serial, preliminary stub

* Imporve initializer

CHANGELOG.md

@@ -5,6 +5,7 @@ All notable changes to this project will be documented in this file.
 
 ## [14.3.0.3]
 ### Added
+- I2C over Serial, preliminary stub
 
 ### Breaking Changed
 

tasmota/include/tasmota_template.h

@@ -226,6 +226,7 @@ enum UserSelectablePins {
   GPIO_BL0906_RX,                       // BL0906 Serial interface
   GPIO_DALI_RX_INV, GPIO_DALI_TX_INV,   // DALI
   GPIO_LD2410S_TX, GPIO_LD2410S_RX,     // HLK-LD2410S
+  GPIO_I2C_SER_TX, GPIO_I2C_SER_RX,     // I2C via Serial using SC18IM704 protocol (xdrv74)
   GPIO_SENSOR_END };
 
 // Error as warning to rethink GPIO usage with max 2045
@@ -499,6 +500,7 @@ const char kSensorNames[] PROGMEM =
   D_SENSOR_BL0906_RX "|"
   D_SENSOR_DALI_RX "_i|" D_SENSOR_DALI_TX "_i|"
   D_SENSOR_LD2410S_TX "|" D_SENSOR_LD2410S_RX "|"
+  D_SENSOR_I2C_SER_TX "|" D_SENSOR_I2C_SER_RX "|"
   ;
 
 const char kSensorNamesFixed[] PROGMEM =
@@ -602,6 +604,10 @@ const uint16_t kGpioNiceList[] PROGMEM = {
 #ifdef USE_PCF8574
   AGPIO(GPIO_PCF8574_INT),              // PCF8574 Interrupt
 #endif  // USE_PCF8574
+#ifdef USE_I2C_SERIAL
+  AGPIO(GPIO_I2C_SER_TX) + MAX_I2C,     // I2C via Serial TX
+  AGPIO(GPIO_I2C_SER_RX) + MAX_I2C,     // I2C via Serial RX
+#endif // USE_I2C_SERIAL
 #endif
 
 #if defined(USE_I2S_AUDIO) || defined (USE_I2S)

tasmota/language/af_AF.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/bg_BG.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/ca_AD.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/cs_CZ.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/de_DE.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/el_GR.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/en_GB.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/es_ES.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/fr_FR.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCl"
 #define D_SENSOR_I2C_SDA       "I2C SDa"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MClk"
 #define D_SENSOR_I2S_BCLK      "I2S BClk"
 #define D_SENSOR_I2S_WS_IN     "I2S BClk In"

tasmota/language/fy_NL.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/he_HE.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/hu_HU.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/it_IT.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20                "DS18x20"
 #define D_SENSOR_I2C_SCL                "I2C - SCL"
 #define D_SENSOR_I2C_SDA                "I2C - SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK               "I2S - MCLK"
 #define D_SENSOR_I2S_BCLK               "I2S - BCLK"
 #define D_SENSOR_I2S_WS_IN              "I2S - BCLK IN"

tasmota/language/ko_KO.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/nl_NL.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/pl_PL.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/pt_BR.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/pt_PT.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/ro_RO.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/ru_RU.h

@@ -699,6 +699,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/sk_SK.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/sv_SE.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/tr_TR.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/uk_UA.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/vi_VN.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/zh_CN.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/language/zh_TW.h

@@ -698,6 +698,8 @@
 #define D_SENSOR_DS18X20       "DS18x20"
 #define D_SENSOR_I2C_SCL       "I2C SCL"
 #define D_SENSOR_I2C_SDA       "I2C SDA"
+#define D_SENSOR_I2C_SER_TX    "I2C Ser TX"
+#define D_SENSOR_I2C_SER_RX    "I2C Ser RX"
 #define D_SENSOR_I2S_MCLK      "I2S MCLK"
 #define D_SENSOR_I2S_BCLK      "I2S BCLK"
 #define D_SENSOR_I2S_WS_IN     "I2S BCLK IN"

tasmota/tasmota_support/support_a_i2c.ino

@@ -78,19 +78,29 @@ bool I2cBegin(int sda, int scl, uint32_t bus, uint32_t frequency) {
   return result;
 }
 
+TwoWire * I2CSerialGetWire(TwoWire * orig_wire, uint8_t bus);
+
 TwoWire& I2cGetWire(uint8_t bus = 0) {
   if ((0 == bus) && TasmotaGlobal.i2c_enabled[0]) {
 #ifdef USE_I2C_BUS2_ESP8266
     I2cSetBus(bus);
 #endif
+#ifdef USE_I2C_SERIAL
+    return I2CSerialGetWire(Wire, bus);
+#else
     return Wire;
+#endif // USE_I2C_SERIAL
   }
 #ifdef USE_I2C_BUS2
   else if ((1 == bus) && TasmotaGlobal.i2c_enabled[1]) {
 #ifdef USE_I2C_BUS2_ESP8266
     I2cSetBus(bus);
 #endif
+#ifdef USE_I2C_SERIAL
+    return I2CSerialGetWire(Wire1, bus);
+#else
     return Wire1;
+#endif // USE_I2C_SERIAL
   }
 #endif  // USE_I2C_BUS2
   else {

tasmota/tasmota_xdrv_driver/xdrv_76_serial_i2c.ino

@@ -0,0 +1,163 @@
+/*
+  xdrv_76_serial_i2c.ino - UART to I2C using SC18IM704 compatible protocol
+
+  Copyright (C) 2024  Stephan Hadinger
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifdef USE_I2C_SERIAL
+
+#define XDRV_76           76
+
+class TwoWireSerial;
+
+struct {
+  bool active = false;
+  uint8_t bus = 0;
+  uint8_t tx = 0;
+  uint8_t rx = 0;
+  TwoWireSerial *WireSerial = nullptr;      // replacement object for TwoWire
+} i2c_serial;
+
+class TwoWireSerial : public TwoWire {
+protected:
+  uint8_t tx;
+  uint8_t rx;
+  TasmotaSerial *serial;                    // serial instance to communicate with SC18IM704
+private:
+public:
+  TwoWireSerial(uint8_t bus_num) : tx(-1), rx(-1), serial(nullptr), TwoWire(bus_num) {
+    AddLog(LOG_LEVEL_DEBUG_MORE, "ISR: TwoWireSerial(%i)", bus_num);
+  };
+  // ~TwoWireSerial() {};
+
+  bool setPins(int _tx, int _rx) {
+    if (_tx >= 0 && _rx >= 0) {
+      tx = _tx;
+      rx = _rx;
+      return true;
+    }
+    return false;
+  }
+
+
+  // virtual bool begin() 
+  // virtual bool begin(uint8_t address) override{ Serial.printf(">>>>>>> begin\n"); return true; };
+  // virtual bool end() = 0;
+  bool beginSerial() {
+    AddLog(LOG_LEVEL_DEBUG_MORE, "ISR: beginSerial");
+    if (tx >= 0 && rx >= 0) {
+      serial = new TasmotaSerial(tx, rx);
+      if (serial) {
+        serial->begin(115200);
+        return true;
+      }
+    }
+    return false;
+  }
+
+  virtual bool setClock(uint32_t freq) override {
+    AddLog(LOG_LEVEL_DEBUG_MORE, "ISR: setClock(%i) -- ignored", freq);
+    return true;
+  }
+
+  virtual void beginTransmission(uint8_t address) override {
+    AddLog(LOG_LEVEL_DEBUG_MORE, "ISR: beginTransmission(0x%02X)", address);
+  };
+  virtual uint8_t endTransmission(bool stopBit) override {
+    AddLog(LOG_LEVEL_DEBUG_MORE, "ISR: endTransmission(%i)", stopBit);
+    return 2;
+  }
+  virtual uint8_t endTransmission(void) override {
+    AddLog(LOG_LEVEL_DEBUG_MORE, "ISR: endTransmission()");
+    return 2;
+  }
+
+  // not used, but redefine to avoid any accidental call
+  virtual size_t requestFrom(uint8_t address, size_t len, bool stopBit) override { return 0; };
+  virtual size_t requestFrom(uint8_t address, size_t len) override { return 0; };
+};
+
+// return the original Wire object or the I2C Serial object
+TwoWire & I2CSerialGetWire(TwoWire & orig_wire, uint8_t bus) {
+  if (i2c_serial.active && i2c_serial.bus == bus) {
+    AddLog(LOG_LEVEL_DEBUG, PSTR("I2C: Bus%d %p"), bus +1, i2c_serial.WireSerial);
+    return *i2c_serial.WireSerial;
+  } else {
+    return orig_wire;
+  }
+}
+
+// Initialize I2C Serial
+// - check if I2C serial is configured on some GPIOs
+// - configure serial bus
+// - register serial bus with Tasmota
+void I2CSerialInit(void) {
+  i2c_serial.active = false;
+  // check if I2C serial is configured on some GPIOs
+  for (uint32_t bus = 0; bus < MAX_I2C; bus++) {
+    if (PinUsed(GPIO_I2C_SER_TX, bus) && PinUsed(GPIO_I2C_SER_RX, bus)) {
+      if (i2c_serial.active) {
+        // Error: I2C Serial was already configured on bus 0, we don't accept a second one
+        AddLog(LOG_LEVEL_ERROR, "I2C: I2C serial can be configured only on 1 bus");
+        continue;
+      }
+      if (TasmotaGlobal.i2c_enabled[bus]) {
+        // Error: I2C was already configured with SDA/SCL on this bus
+        AddLog(LOG_LEVEL_ERROR, "I2C: I2C serial failed on bus %i because SDA/SCL already configured", bus + 1);
+      } else {
+        // all good
+        i2c_serial.bus = bus;
+        i2c_serial.tx = Pin(GPIO_I2C_SER_TX, bus);
+        i2c_serial.rx = Pin(GPIO_I2C_SER_RX, bus);
+        i2c_serial.active = true;
+      }
+    }
+  }
+  // configure serial bus
+  if (i2c_serial.active) {
+    i2c_serial.WireSerial = new TwoWireSerial(1);   // TODO is it ok to use UART 1 ?
+    i2c_serial.WireSerial->setPins(i2c_serial.tx, i2c_serial.rx);
+    if (i2c_serial.WireSerial->beginSerial()) {
+      TasmotaGlobal.i2c_enabled[i2c_serial.bus] = true;          // enable at Tasmota level
+      AddLog(LOG_LEVEL_INFO, "I2C: I2C serial configured on GPIO TX %i / RX %i for bus %i", i2c_serial.tx, i2c_serial.rx, i2c_serial.bus + 1);
+    } else {
+      delete i2c_serial.WireSerial;
+      i2c_serial.active = false;
+    }
+  }
+  AddLog(LOG_LEVEL_DEBUG_MORE, "I2C: I2C serial active %i, bus %i, tx %i / rx %i, wire %p", i2c_serial.active, i2c_serial.bus + 1, i2c_serial.tx, i2c_serial.rx, i2c_serial.WireSerial);
+}
+
+/*********************************************************************************************\
+ * Interface
+\*********************************************************************************************/
+
+bool Xdrv76(uint32_t function) {
+  bool result = false;
+
+  if (FUNC_PRE_INIT == function) {
+    I2CSerialInit();
+  } else if (i2c_serial.active) {
+    switch (function) {
+      case FUNC_ACTIVE:
+        result = true;
+        break;
+    }
+  }
+  return result;
+}
+
+#endif  // USE_I2C_SERIAL