diff --git a/sw/airborne/arch/sim/sim_ahrs.c b/sw/airborne/arch/sim/sim_ahrs.c
new file mode 100644
index 0000000000..6c46ef76da
--- /dev/null
+++ b/sw/airborne/arch/sim/sim_ahrs.c
@@ -0,0 +1,31 @@
+/** \file sim_ahrs.c
+ *  \brief Regroup functions to simulate an ahrs
+ *
+ * Ahrs soft simulation. OCaml binding.
+ */
+
+
+#include <inttypes.h>
+#include <caml/mlvalues.h>
+#include "std.h"
+
+float sim_phi;    ///< in radians
+float sim_theta;  ///< in radians
+float sim_psi;    ///< in radians
+float sim_p;      ///< in radians/s
+float sim_q;      ///< in radians/s
+bool_t ahrs_sim_available;
+
+// Updates from Ocaml sim
+value provide_attitude_and_rates(value phi, value theta, value psi, value p, value q) {
+  sim_phi = Double_val(phi);
+  sim_theta = Double_val(theta);
+  sim_psi = - Double_val(psi) + M_PI/2.;
+  sim_p = Double_val(p);
+  sim_q = Double_val(q);
+
+  ahrs_sim_available = TRUE;
+
+  return Val_unit;
+}
+