Moving address locking to init method in BMX280 sensor (#353)

code/espurna/sensors/BMX280Sensor.h

@@ -72,10 +72,6 @@ class BMX280Sensor : public I2CSensor {
             _dirty = false;
             _chip = 0;
 
-            // I2C auto-discover
-            _address = _begin_i2c(_address, sizeof(BMX280Sensor::addresses), BMX280Sensor::addresses);
-            if (_address == 0) return;
-
             // Init
             _init();
 
@@ -194,13 +190,26 @@ class BMX280Sensor : public I2CSensor {
             // Make sure sensor had enough time to turn on. BMX280 requires 2ms to start up
             delay(10);
 
+            // I2C auto-discover
+            _address = _begin_i2c(_address, sizeof(BMX280Sensor::addresses), BMX280Sensor::addresses);
+            if (_address == 0) return;
+
             // Check sensor correctly initialized
             _chip = i2c_read_uint8(_address, BMX280_REGISTER_CHIPID);
             if ((_chip != BMX280_CHIP_BME280) && (_chip != BMX280_CHIP_BMP280)) {
+
                 _chip = 0;
                 i2cReleaseLock(_address);
+                _previous_address = 0;
                 _error = SENSOR_ERROR_UNKNOWN_ID;
+
+                // Setting _address to 0 forces auto-discover
+                // This might be necessary at this stage if there is a
+                // different sensor in the hardcoded address
+                _address = 0;
+
                 return;
+
             }
 
             _count = 0;

code/espurna/sensors/I2CSensor.h

@@ -40,28 +40,32 @@ class I2CSensor : public BaseSensor {
         // Specific for I2C sensors
         unsigned char _begin_i2c(unsigned char address, size_t size, unsigned char * addresses) {
 
+            // If we have already locked this address for this sensor quit
+            if ((address > 0) && (address == _previous_address)) {
+                return _previous_address;
+            }
+
             // Check if we should release a previously locked address
-            if (_previous_address != address) {
+            if ((_previous_address > 0) && (_previous_address != address)) {
                 i2cReleaseLock(_previous_address);
+                _previous_address = 0;
             }
 
-            // If we have already an address, check it is not locked
-            if (address && !i2cGetLock(address)) {
-                _error = SENSOR_ERROR_I2C;
-
-            // If we don't have an address...
-            } else {
-
-                // Trigger auto-discover
-                address = i2cFindAndLock(size, addresses);
+            // If requesting a specific address, try to ger a lock to it
+            if ((0 < address) && i2cGetLock(address)) {
+                _previous_address = address;
+                return _previous_address;
+            }
 
-                // If still nothing exit with error
-                if (address == 0) _error = SENSOR_ERROR_I2C;
+            // If everything else fails, perform an auto-discover
+            _previous_address = i2cFindAndLock(size, addresses);
 
+            // Flag error
+            if (0 == _previous_address) {
+                _error = SENSOR_ERROR_I2C;
             }
 
-            _previous_address = address;
-            return address;
+            return _previous_address;
 
         }
 

code/espurna/sensors/SI7021Sensor.h

@@ -121,9 +121,17 @@ class SI7021Sensor : public I2CSensor {
             _chip = i2c_read_uint8(_address);
 
             if ((_chip != SI7021_CHIP_SI7021) & (_chip != SI7021_CHIP_HTU21D)) {
+
+                _count = 0;
                 i2cReleaseLock(_address);
+                _previous_address = 0;
                 _error = SENSOR_ERROR_UNKNOWN_ID;
-                _count = 0;
+
+                // Setting _address to 0 forces auto-discover
+                // This might be necessary at this stage if there is a
+                // different sensor in the hardcoded address
+                _address = 0;
+
             } else {
                 _count = 2;
             }