[sim] some preliminary fixes for simulating aspirin imu

sw/airborne/arch/sim/subsystems/imu/imu_aspirin_arch.c

@@ -26,7 +26,7 @@
 #include "generated/airframe.h"
 
 void imu_aspirin_arch_init(void) {
-
+  imu_aspirin.status = AspirinStatusIdle;
 }
 
 
@@ -35,7 +35,7 @@ void imu_aspirin_arch_init(void) {
 
 void imu_feed_gyro_accel(void) {
 
-#if 1
+#if 0
   // the high byte is in buf[0], low byte in buf[1], etc.
   imu_aspirin.i2c_trans_gyro.buf[0] = ((int16_t)sensors.gyro.value.x) >> 8;
   imu_aspirin.i2c_trans_gyro.buf[1] = ((int16_t)sensors.gyro.value.x) & 0xff;

sw/airborne/subsystems/imu/imu_aspirin.h

@@ -234,8 +234,22 @@ static inline void imu_aspirin_event(void (* _gyro_handler)(void), void (* _acce
 
 }
 
+#ifndef SITL
 #define ImuEvent(_gyro_handler, _accel_handler, _mag_handler) do {		\
   imu_aspirin_event(_gyro_handler, _accel_handler, _mag_handler); \
 } while(0);
+#else
+#define ImuEvent(_gyro_handler, _accel_handler, _mag_handler) { \
+    if (imu_aspirin.accel_available) {                          \
+      imu_aspirin.accel_available = FALSE;                      \
+      _accel_handler();                                         \
+    }                                                           \
+    if (imu_aspirin.gyro_available_blaaa) {                     \
+      imu_aspirin.gyro_available_blaaa = FALSE;                 \
+      _gyro_handler();                                          \
+    }                                                           \
+    ImuMagEvent(_mag_handler);                                  \
+  }
+#endif
 
 #endif /* IMU_ASPIRIN_H */