Merge pull request #53 from SkUrRiEr/address_calc_define

Add a macro to calculate the I2C address based on the A0 and A1 pads

Author: ladyada

Adafruit_INA219.h

@@ -22,6 +22,21 @@
 #include <Adafruit_I2CDevice.h>
 #include <Wire.h>
 
+/** calculated I2C address: 0 = GND, 1 = V+ **/
+/* The address is controlled by the A0 and A1 inputs on the INA219:
+ *
+ * Calculated address: b100ABCD
+ * A0 controls C and D: GND = 00, V+ = 01, SDA = 10, SCL = 11
+ * A1 controls A and B: GND = 00, V+ = 01, SDA = 10, SCL = 11
+ *
+ * E.g. if A0 is tied to ground and A1 is tied to V+,
+ * the resulting address is b1000100 = 0x44
+ *
+ * SDA and SCL options aren't implemented.
+ */
+#define INA219_CALC_ADDRESS(INA_ADDR0, INA_ADDR1)                              \
+  (0x40 | (INA_ADDR0 != 0 ? 0x01 : 0x00) | (INA_ADDR1 != 0 ? 0x04 : 0x00))
+
 /** default I2C address **/
 #define INA219_ADDRESS (0x40) // 1000000 (A0+A1=GND)