first upload

src/I2CCommands.h

@@ -0,0 +1,6 @@
+#ifndef I2C_COMMANDS_H
+#define I2C_COMMANDS_H
+
+#define CMD_CHANGE_ADDR 0xAA // Use the same value as in your slave
+
+#endif

src/I2CMasterUtils.cpp

@@ -0,0 +1,36 @@
+#include "I2CMasterUtils.h"
+#include "I2CCommands.h"
+
+void I2CMasterUtils::scanI2C(Stream &output) {
+    output.println("Scanning for I2C devices...");
+    for (uint8_t addr = 1; addr < 127; addr++) {
+        Wire.beginTransmission(addr);
+        if (Wire.endTransmission() == 0) {
+            output.print("Found device at 0x");
+            output.println(addr, HEX);
+        }
+    }
+}
+
+void I2CMasterUtils::changeSlaveAddress(uint8_t oldAddr, uint8_t newAddr, Stream &output) {
+    Wire.beginTransmission(oldAddr);
+    Wire.write(CMD_CHANGE_ADDR); // Use the command code from I2CCommands.h
+    Wire.write(newAddr);
+    Wire.endTransmission();
+    output.print("Sent address change command to 0x");
+    output.print(oldAddr, HEX);
+    output.print(" -> 0x");
+    output.println(newAddr, HEX);
+}
+
+bool I2CMasterUtils::parseChangeAddressCommand(const String &input, uint8_t &oldAddr, uint8_t &newAddr) {
+    if (!input.startsWith("ch")) return false;
+    int o, n;
+    int matched = sscanf(input.c_str(), "ch %x %x", &o, &n);
+    if (matched == 2) {
+        oldAddr = (uint8_t)o;
+        newAddr = (uint8_t)n;
+        return true;
+    }
+    return false;
+}

src/I2CMasterUtils.h

@@ -0,0 +1,14 @@
+#ifndef I2CMASTERUTILS_H
+#define I2CMASTERUTILS_H
+
+#include <Arduino.h>
+#include <Wire.h>
+
+class I2CMasterUtils {
+public:
+    static void scanI2C(Stream &output = Serial);
+    static void changeSlaveAddress(uint8_t oldAddr, uint8_t newAddr, Stream &output = Serial);
+    static bool parseChangeAddressCommand(const String &input, uint8_t &oldAddr, uint8_t &newAddr);
+};
+
+#endif

src/I2CRelay.cpp

@@ -0,0 +1,35 @@
+#include <Wire.h>
+#include <Arduino.h>
+#include "I2CRelay.h"
+#include "I2CMasterUtils.h"
+#include "I2CCommands.h"
+
+RelayI2CMaster::RelayI2CMaster(uint8_t slaveAddress) : _slaveAddress(slaveAddress) {}
+
+void RelayI2CMaster::setAddress(uint8_t newAddress) {
+    _slaveAddress = newAddress;
+}
+
+void RelayI2CMaster::begin() {
+    Wire.begin();
+}
+
+void RelayI2CMaster::setRelay(uint8_t relayIndex, bool state) {
+    Wire.beginTransmission(_slaveAddress);
+    Wire.write(relayIndex);
+    Wire.write(state ? 1 : 0);
+    Wire.endTransmission();
+}
+
+uint8_t RelayI2CMaster::scanDevices(uint8_t* foundAddresses, uint8_t maxDevices) {
+    uint8_t count = 0;
+    for(uint8_t addr = 1; addr < 127; addr++) {
+        Wire.beginTransmission(addr);
+        if(Wire.endTransmission() == 0) {
+            if(count < maxDevices) {
+                foundAddresses[count++] = addr;
+            }
+        }
+    }
+    return count;
+}

src/I2CRelay.h

@@ -0,0 +1,20 @@
+#ifndef RELAY_I2C_MASTER_H
+#define RELAY_I2C_MASTER_H
+
+#include <Arduino.h>
+#include <Wire.h>
+
+class RelayI2CMaster {
+public:
+    RelayI2CMaster(uint8_t slaveAddress);
+    void begin();
+    void setRelay(uint8_t relayIndex, bool state);
+    uint8_t scanDevices(uint8_t* foundAddresses, uint8_t maxDevices);
+    void setAddress(uint8_t newAddress);
+    void handleI2CCommand();
+    
+private:
+    uint8_t _slaveAddress;
+};
+
+#endif