diff --git a/conf/modules/MPPT.xml b/conf/modules/MPPT.xml
index d50df38d8c..a77b503ff6 100644
--- a/conf/modules/MPPT.xml
+++ b/conf/modules/MPPT.xml
@@ -18,7 +18,7 @@
     <file name="MPPT.h"/>
   </header>
   <init fun="MPPT_init()"/>
-  <periodic fun="MPPT_periodic()" freq="8." delay="4" autorun="TRUE"/>
+  <periodic fun="MPPT_periodic()" freq="8." delay="0.15" autorun="TRUE"/>
   <makefile target="ap">
     <file name="MPPT.c"/>
   </makefile>
diff --git a/conf/modules/alt_srf08.xml b/conf/modules/alt_srf08.xml
index 0fed20f9f1..501806f45c 100644
--- a/conf/modules/alt_srf08.xml
+++ b/conf/modules/alt_srf08.xml
@@ -8,10 +8,10 @@
     <file name="alt_srf08.h"/>
   </header>
   <init fun="srf08_init()"/>
-  <periodic fun="srf08_initiate_ranging()" freq="1"/>
-  <!-- 65ms since initiate_ranging() (the spec ask for 65ms),
-       delay="4", 60Hz, 4x 16.7ms = 66.7ms -->
-  <periodic fun="srf08_receive()" freq="1" delay="4"/>
+  <periodic fun="srf08_initiate_ranging()" freq="1" delay="0."/>
+  <!-- 70ms (delay 0.7 with freq = 1Hz since initiate_ranging()
+       (the spec ask for 65ms) -->
+  <periodic fun="srf08_receive()" freq="1" delay="0.07"/>
   <event fun="srf08_event()"/>
   <makefile>
     <file name="alt_srf08.c"/>
diff --git a/conf/modules/dust_gp2y.xml b/conf/modules/dust_gp2y.xml
index fcfaf6147d..1f1a591fa1 100644
--- a/conf/modules/dust_gp2y.xml
+++ b/conf/modules/dust_gp2y.xml
@@ -12,7 +12,7 @@
     <file name="dust_gp2y.h"/>
   </header>
   <init fun="dust_gp2y_init()"/>
-  <periodic fun="dust_gp2y_periodic()" freq="4" delay="1"/>
+  <periodic fun="dust_gp2y_periodic()" freq="4" delay="0.6"/>
   <event fun="dust_gp2y_event()"/>
   <makefile target="ap">
     <file name="dust_gp2y.c"/>
diff --git a/conf/modules/gsm.xml b/conf/modules/gsm.xml
index 6a54c37822..5d9e942afe 100644
--- a/conf/modules/gsm.xml
+++ b/conf/modules/gsm.xml
@@ -8,7 +8,7 @@
     <file name="gsm.h"/>
   </header>
   <init fun="gsm_init()"/>
-  <periodic fun="gsm_init_report()" period="60." delay="3599" autorun="TRUE"/>
+  <periodic fun="gsm_init_report()" period="60." delay="0.95" autorun="TRUE"/>
   <periodic fun="gsm_send_report()" period="60." autorun="FALSE"/>
   <event fun="gsm_event()"/>
   <makefile>
diff --git a/conf/modules/humid_htm_b71.xml b/conf/modules/humid_htm_b71.xml
index d0b2b7b067..92c5562509 100644
--- a/conf/modules/humid_htm_b71.xml
+++ b/conf/modules/humid_htm_b71.xml
@@ -9,8 +9,8 @@
     <file name="humid_htm_b71.h"/>
   </header>
   <init fun="humid_htm_init()"/>
-  <periodic fun="humid_htm_start()" freq="4" delay="10"/>
-  <periodic fun="humid_htm_read()"  freq="4" delay="14"/>
+  <periodic fun="humid_htm_start()" freq="4" delay="0.66"/>
+  <periodic fun="humid_htm_read()"  freq="4" delay="0.9"/>
   <event fun="humid_htm_event()"/>
   <makefile target="ap">
     <configure name="HTM_I2C_DEV" default="i2c0" case="upper|lower"/>
diff --git a/conf/modules/humid_sht_i2c.xml b/conf/modules/humid_sht_i2c.xml
index 75d7caac06..a956442058 100644
--- a/conf/modules/humid_sht_i2c.xml
+++ b/conf/modules/humid_sht_i2c.xml
@@ -9,9 +9,9 @@
     <file name="humid_sht_i2c.h"/>
   </header>
   <init fun="humid_sht_init_i2c()"/>
-  <periodic fun="humid_sht_periodic_i2c()" freq="4" delay="0"/>
-  <periodic fun="humid_sht_p_temp()" freq="4" delay="6"/>
-  <periodic fun="humid_sht_p_humid()"  freq="4" delay="9"/>
+  <periodic fun="humid_sht_periodic_i2c()" freq="4" delay="0."/>
+  <periodic fun="humid_sht_p_temp()" freq="4" delay="0.4"/>
+  <periodic fun="humid_sht_p_humid()"  freq="4" delay="0.6"/>
   <event fun="humid_sht_event_i2c()"/>
   <makefile target="ap">
     <file name="humid_sht_i2c.c"/>
diff --git a/conf/modules/wind_gfi.xml b/conf/modules/wind_gfi.xml
index 0769bb9f70..24dd95e567 100644
--- a/conf/modules/wind_gfi.xml
+++ b/conf/modules/wind_gfi.xml
@@ -8,7 +8,7 @@
     <file name="wind_gfi.h"/>
   </header>
   <init fun="wind_gfi_init()"/>
-  <periodic fun="wind_gfi_periodic()" freq="4" delay="2"/>
+  <periodic fun="wind_gfi_periodic()" freq="4" delay="0.13"/>
   <event fun="wind_gfi_event()"/>
   <makefile target="ap">
     <file name="wind_gfi.c"/>
diff --git a/sw/lib/ocaml/module.ml b/sw/lib/ocaml/module.ml
index a1d88eea8b..938f4c999d 100644
--- a/sw/lib/ocaml/module.ml
+++ b/sw/lib/ocaml/module.ml
@@ -141,7 +141,7 @@ type periodic = {
     call: string;
     fname: string;
     period_freq: period_freq;
-    delay: int option;
+    delay: float option;
     start: string option;
     stop: string option;
     autorun: autorun
@@ -149,7 +149,7 @@ type periodic = {
 
 let parse_periodic = fun xml ->
   let get = fun x -> ExtXml.attrib_opt xml x in
-  let geti = fun x ->  ExtXml.attrib_opt_int xml x in
+  let getf = fun x ->  ExtXml.attrib_opt_float xml x in
   let call = snd (List.find (fun (a, _) -> Compat.lowercase_ascii a = "fun")
                  (Xml.attribs xml)) in
   let call_regexp = Str.regexp "\\([a-zA-Z_][a-zA-Z0-9_]*\\)\\(.*\\)" in
@@ -176,7 +176,7 @@ let parse_periodic = fun xml ->
         with _ -> Period p
       end
    in
-  { call; fname; period_freq; delay = geti "delay";
+  { call; fname; period_freq; delay = getf "delay";
     start = get "start"; stop = get "stop";
     autorun = match get "autorun" with
       | None -> Lock
diff --git a/sw/tools/generators/gen_modules.ml b/sw/tools/generators/gen_modules.ml
index 533562882f..610785cac5 100644
--- a/sw/tools/generators/gen_modules.ml
+++ b/sw/tools/generators/gen_modules.ml
@@ -111,7 +111,12 @@ let get_functions_modulos = fun modules ->
       let p, _ = get_period_and_freq x in
       let d = begin try
         let _d = float_of_string (Xml.attrib x "delay") in
-        if _d > 0.95 then _d /. 65536. else _d (* try to keep some backward compatibility *)
+        if _d > 0.99 then
+          begin
+            fprintf stderr "Warning: 'delay' attribute should be a float value between 0. and 1.\n";
+            _d /. 65536.
+          end
+        else _d (* try to keep some backward compatibility *)
         with _ ->
           delay := !delay +. 0.1;
           if !delay > 0.9 then delay := 0.;