diff --git a/sw/airborne/boards/booz/test_baro.c b/sw/airborne/boards/booz/test_baro.c
index 32ffe4f672..5b179ff240 100644
--- a/sw/airborne/boards/booz/test_baro.c
+++ b/sw/airborne/boards/booz/test_baro.c
@@ -47,7 +47,7 @@ int main(void) {
   main_init();
 
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
     main_event_task();
   }
@@ -57,7 +57,7 @@ int main(void) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   booz2_analog_init();
   baro_init();
   mcu_int_enable();
diff --git a/sw/airborne/boards/lisa_l/test_baro.c b/sw/airborne/boards/lisa_l/test_baro.c
index 9808020358..6dad99c825 100644
--- a/sw/airborne/boards/lisa_l/test_baro.c
+++ b/sw/airborne/boards/lisa_l/test_baro.c
@@ -33,6 +33,8 @@
 #include "mcu_periph/sys_time.h"
 #include "mcu_periph/uart.h"
 
+#include "led.h"
+
 #include "subsystems/datalink/downlink.h"
 
 #include "subsystems/sensors/baro.h"
@@ -50,7 +52,7 @@ int main(void) {
   main_init();
 
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
     main_event_task();
   }
@@ -60,7 +62,7 @@ int main(void) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   baro_init();
 
   //  DEBUG_SERVO1_INIT();
diff --git a/sw/airborne/booz/test/booz2_test_buss_bldc_hexa.c b/sw/airborne/booz/test/booz2_test_buss_bldc_hexa.c
index d1fdbeed2e..b90dcbe32d 100644
--- a/sw/airborne/booz/test/booz2_test_buss_bldc_hexa.c
+++ b/sw/airborne/booz/test/booz2_test_buss_bldc_hexa.c
@@ -51,7 +51,7 @@ static inline void main_event_task( void );
 int main( void ) {
   main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
     main_event_task();
   }
@@ -60,7 +60,7 @@ int main( void ) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   mcu_int_enable();
 }
 
diff --git a/sw/airborne/booz/test/booz2_test_crista.c b/sw/airborne/booz/test/booz2_test_crista.c
index 05cc0a0895..08f831ed05 100644
--- a/sw/airborne/booz/test/booz2_test_crista.c
+++ b/sw/airborne/booz/test/booz2_test_crista.c
@@ -45,7 +45,7 @@ static inline void on_imu_event(void);
 int main( void ) {
   main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
     main_event_task();
   }
@@ -54,7 +54,7 @@ int main( void ) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   led_init();
 
 /*   LED_ON(4); */
diff --git a/sw/airborne/booz/test/booz2_test_gps.c b/sw/airborne/booz/test/booz2_test_gps.c
index 13a3f75067..3ca4cacd46 100644
--- a/sw/airborne/booz/test/booz2_test_gps.c
+++ b/sw/airborne/booz/test/booz2_test_gps.c
@@ -39,7 +39,7 @@ static void on_gps_sol(void);
 int main( void ) {
   main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
     main_event_task();
   }
@@ -48,7 +48,7 @@ int main( void ) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   led_init();
   gps_init();
   mcu_int_enable();
diff --git a/sw/airborne/booz/test/booz2_test_max1168.c b/sw/airborne/booz/test/booz2_test_max1168.c
index 5e12c79ee1..8e3ec2e42f 100644
--- a/sw/airborne/booz/test/booz2_test_max1168.c
+++ b/sw/airborne/booz/test/booz2_test_max1168.c
@@ -48,7 +48,7 @@ static void SSP_ISR(void) __attribute__((naked));
 int main( void ) {
   main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
     main_event_task();
   }
@@ -57,7 +57,7 @@ int main( void ) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
 
   main_init_ssp();
   max1168_init();
diff --git a/sw/airborne/booz/test/booz2_test_micromag.c b/sw/airborne/booz/test/booz2_test_micromag.c
index ef97368aeb..b5c32c13c8 100644
--- a/sw/airborne/booz/test/booz2_test_micromag.c
+++ b/sw/airborne/booz/test/booz2_test_micromag.c
@@ -50,7 +50,7 @@ static void SSP_ISR(void) __attribute__((naked));
 int main( void ) {
   main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
     main_event_task();
   }
@@ -59,7 +59,7 @@ int main( void ) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   led_init();
 
   uart1_init_tx();
diff --git a/sw/airborne/booz/test/booz2_test_usb.c b/sw/airborne/booz/test/booz2_test_usb.c
index 46d61ddf50..fc6c382eda 100644
--- a/sw/airborne/booz/test/booz2_test_usb.c
+++ b/sw/airborne/booz/test/booz2_test_usb.c
@@ -43,7 +43,7 @@ static inline void main_event_task( void );
 int main( void ) {
   main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
     main_event_task();
   }
@@ -52,7 +52,7 @@ int main( void ) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   led_init();
 
   VCOM_init();
diff --git a/sw/airborne/csc/csc_ap_main.c b/sw/airborne/csc/csc_ap_main.c
index bb96cc56ca..757dcbd75c 100644
--- a/sw/airborne/csc/csc_ap_main.c
+++ b/sw/airborne/csc/csc_ap_main.c
@@ -142,7 +142,7 @@ static void on_gpspos_cmd( struct CscGPSPosMsg *msg )
 static void csc_main_init( void ) {
 
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   led_init();
 
   Uart0Init();
@@ -213,7 +213,7 @@ static void csc_main_event( void )
 int main( void ) {
   csc_main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       csc_main_periodic();
     csc_main_event();
   }
diff --git a/sw/airborne/csc/csc_main.c b/sw/airborne/csc/csc_main.c
index 6a84dec50e..40f7db23ec 100644
--- a/sw/airborne/csc/csc_main.c
+++ b/sw/airborne/csc/csc_main.c
@@ -67,7 +67,7 @@ struct NedCoor_i booz_ins_gps_speed_cm_s_ned;
 static void csc_main_init( void ) {
 
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   led_init();
 
 #ifdef USE_UART0
@@ -219,7 +219,7 @@ static inline void on_motor_cmd(struct CscMotorMsg *msg)
 int main( void ) {
   csc_main_init();
   while(1) {
-  if (sys_time_periodic())
+  if (sys_time_check_and_ack_timer(0))
     csc_main_periodic();
     csc_main_event();
   }
diff --git a/sw/airborne/csc/mercury_csc_main.c b/sw/airborne/csc/mercury_csc_main.c
index 742ccfb034..ce9c725186 100644
--- a/sw/airborne/csc/mercury_csc_main.c
+++ b/sw/airborne/csc/mercury_csc_main.c
@@ -81,7 +81,7 @@ static uint32_t can_msg_count = 0;
 static void csc_main_init( void ) {
 
 	hw_init();
-	sys_time_init();
+	sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
 	led_init();
 
 	actuators_init();
@@ -252,7 +252,7 @@ int main( void ) {
 	csc_main_init();
 //	Uart0PrintString("Hello");
 	while(1) {
-		if (sys_time_periodic()) {
+		if (sys_time_check_and_ack_timer(0)) {
 			csc_main_periodic();
 		}
 		csc_main_event();
diff --git a/sw/airborne/csc/mercury_main.c b/sw/airborne/csc/mercury_main.c
index 62bca80df7..1ce22fb4b5 100644
--- a/sw/airborne/csc/mercury_main.c
+++ b/sw/airborne/csc/mercury_main.c
@@ -74,7 +74,7 @@ static inline void csc_main_event( void );
 int main( void ) {
   csc_main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       csc_main_periodic();
     csc_main_event();
   }
@@ -106,7 +106,7 @@ static void on_rc_cmd(struct CscRCMsg *msg)
 static inline void csc_main_init( void ) {
 
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   led_init();
 
   Uart0Init();
diff --git a/sw/airborne/csc/ppm_bridge_main.c b/sw/airborne/csc/ppm_bridge_main.c
index 3a73086901..1cd8521013 100644
--- a/sw/airborne/csc/ppm_bridge_main.c
+++ b/sw/airborne/csc/ppm_bridge_main.c
@@ -53,7 +53,7 @@ static uint16_t cpu_time = 0;
 static void csc_main_init( void ) {
 
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   led_init();
 
   Uart0Init();
@@ -123,7 +123,7 @@ static void csc_main_event( void )
 int main( void ) {
   csc_main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       csc_main_periodic();
     csc_main_event();
   }
diff --git a/sw/airborne/firmwares/beth/main_beth.c b/sw/airborne/firmwares/beth/main_beth.c
index 4ae748aa4a..4f1ff6ae6f 100644
--- a/sw/airborne/firmwares/beth/main_beth.c
+++ b/sw/airborne/firmwares/beth/main_beth.c
@@ -17,7 +17,7 @@ static inline void main_on_bench_sensors( void );
 int main( void ) {
   main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
   }
   return 0;
@@ -25,7 +25,7 @@ int main( void ) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   mcu_int_enable();
 }
 
diff --git a/sw/airborne/firmwares/beth/main_coders.c b/sw/airborne/firmwares/beth/main_coders.c
index bf615dc328..eb086428ab 100644
--- a/sw/airborne/firmwares/beth/main_coders.c
+++ b/sw/airborne/firmwares/beth/main_coders.c
@@ -64,7 +64,7 @@ int main(void) {
   servos[3] = 4;
 
   while (1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic();
     main_event();
   }
@@ -74,7 +74,7 @@ int main(void) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   main_init_adc();
   bench_sensors_init();
   mcu_int_enable();
diff --git a/sw/airborne/firmwares/beth/main_stm32.c b/sw/airborne/firmwares/beth/main_stm32.c
index 5fb4667990..af702db5ee 100644
--- a/sw/airborne/firmwares/beth/main_stm32.c
+++ b/sw/airborne/firmwares/beth/main_stm32.c
@@ -54,7 +54,7 @@ int main(void) {
   main_init();
 
   while (1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic();
     main_event();
   }
@@ -63,7 +63,7 @@ int main(void) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   actuators_init();
   //radio_control_init();
   imu_init();
diff --git a/sw/airborne/firmwares/setup/setup_actuators.c b/sw/airborne/firmwares/setup/setup_actuators.c
index 9c7bf5b7b2..c914b1bdc9 100644
--- a/sw/airborne/firmwares/setup/setup_actuators.c
+++ b/sw/airborne/firmwares/setup/setup_actuators.c
@@ -48,7 +48,7 @@ void dl_parse_msg( void ) {
 
 void init_fbw( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   led_init();
 
   PprzUartInit();
diff --git a/sw/airborne/firmwares/wind_tunnel/main.c b/sw/airborne/firmwares/wind_tunnel/main.c
index 936c5b1a44..30bd9f0c19 100644
--- a/sw/airborne/firmwares/wind_tunnel/main.c
+++ b/sw/airborne/firmwares/wind_tunnel/main.c
@@ -30,7 +30,7 @@ uint16_t datalink_time;
 int main( void ) {
   main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
     main_event_task( );
   }
@@ -39,7 +39,7 @@ int main( void ) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   led_init();
   uart0_init();
 
diff --git a/sw/airborne/firmwares/wind_tunnel/main_mb.c b/sw/airborne/firmwares/wind_tunnel/main_mb.c
index 7c1830154f..75354cc7b0 100644
--- a/sw/airborne/firmwares/wind_tunnel/main_mb.c
+++ b/sw/airborne/firmwares/wind_tunnel/main_mb.c
@@ -29,7 +29,7 @@ uint16_t datalink_time;
 int main( void ) {
   main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
     main_event_task( );
   }
@@ -38,7 +38,7 @@ int main( void ) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   led_init();
   uart0_init();
 
diff --git a/sw/airborne/fms/lpc_test_spi.c b/sw/airborne/fms/lpc_test_spi.c
index 481fa3505c..2b4b90fedf 100644
--- a/sw/airborne/fms/lpc_test_spi.c
+++ b/sw/airborne/fms/lpc_test_spi.c
@@ -42,7 +42,7 @@ static void SPI0_ISR(void) __attribute__((naked));
 int main( void ) {
   main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
     main_event_task();
   }
@@ -51,7 +51,7 @@ int main( void ) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   main_spi_init();
   mcu_int_enable();
 }
diff --git a/sw/airborne/sd_card/main.c b/sw/airborne/sd_card/main.c
index 2c7d130d2e..25342b9d7d 100644
--- a/sw/airborne/sd_card/main.c
+++ b/sw/airborne/sd_card/main.c
@@ -26,7 +26,7 @@ uint16_t datalink_time;
 int main( void ) {
   main_init();
   while(1) {
-    if (sys_time_periodic())
+    if (sys_time_check_and_ack_timer(0))
       main_periodic_task();
     main_event_task( );
   }
@@ -35,7 +35,7 @@ int main( void ) {
 
 static inline void main_init( void ) {
   mcu_init();
-  sys_time_init();
+  sys_time_register_timer((1./PERIODIC_FREQUENCY), NULL);
   led_init();
   Uart0Init();