[modules] minor cleanup of ezcurrent sensor

conf/modules/ezcurrent.xml

@@ -13,7 +13,7 @@
   <periodic fun="ezcurrent_read_periodic()" freq="1."/>
   <event fun="ezcurrent_read_event()"/>
 
-  <makefile>
+  <makefile target="ap">
     <file name="ezcurrent.c"/>
     <!-- This disables the standard electrical monitoring system -->
     <define name="DISABLE_ELECTRICAL" description="Disable default electrical handling"/>

sw/airborne/modules/sensors/ezcurrent.c

@@ -56,19 +56,23 @@ void ezcurrent_init( void ) {
 }
 
 void ezcurrent_read_periodic( void ) {
-#ifndef SITL
   if (ezcurrent_i2c_trans.status == I2CTransDone) {
     I2CReceive(EZCURRENT_I2C_DEV, ezcurrent_i2c_trans, ezcurrent_i2c_trans.slave_addr, 10);
   }
-#endif //SITL
 }
 
+#define Uint16FromBuf(_buf,_idx) ((uint16_t)((_buf[_idx+1]<<8) | _buf[_idx]))
+#define Int16FromBuf(_buf,_idx) ((int16_t)((_buf[_idx+1]<<8) | _buf[_idx]))
+
 void ezcurrent_read_event( void ) {
   if (ezcurrent_i2c_trans.status == I2CTransSuccess) {
-    // Get electrical information from buffer
-    electrical.vsupply = ((uint16_t)( (((ezcurrent_i2c_trans.buf[3]) << 8) + ezcurrent_i2c_trans.buf[2]) * 0.01f) );
-    electrical.current = (((int32_t)(ezcurrent_i2c_trans.buf[9]) << 8) + (int32_t)(ezcurrent_i2c_trans.buf[8])) * 100;
-    electrical.consumed = ((int32_t)(ezcurrent_i2c_trans.buf[7]) << 8) + (int32_t)(ezcurrent_i2c_trans.buf[6]);
+    /* voltage of EzOSD sensor is provided in mV, convert to deciVolt */
+    electrical.vsupply = Uint16FromBuf(ezcurrent_i2c_trans.buf, 2) / 100;
+    /* consumed ? in mAh */
+    electrical.consumed = Int16FromBuf(ezcurrent_i2c_trans.buf, 6);
+    /* sensor provides current in 1e-1 Ampere, convert to mA */
+    electrical.current = Int16FromBuf(ezcurrent_i2c_trans.buf, 8) * 100;
+
     // Transaction has been read
     ezcurrent_i2c_trans.status = I2CTransDone;
   } else if ( ezcurrent_i2c_trans.status == I2CTransFailed ) {

sw/airborne/subsystems/electrical.h

@@ -5,9 +5,9 @@
 
 struct Electrical {
 
-  uint16_t vsupply; /* supply in decivolts */
-  int32_t current; /* current in milliamps */
-  int32_t consumed; /* consumption in mAh */
+  uint16_t vsupply;  ///< supply voltage in decivolts
+  int32_t current;   ///< current in milliamps
+  int32_t consumed;  ///< consumption in mAh
 
 };