Iotthd 4224 (ARMmbed#2403)

* FHSS WS: use large retry backoff when broadcast schedule unknown

* FHSS WS: Use large randomized retry backoff when TX/RX slots unknown

Author: Jarkko Paso

source/Service_Libs/fhss/fhss_ws.c

@@ -295,6 +295,7 @@ static void fhss_broadcast_handler(const fhss_api_t *fhss_api, uint16_t delay)
         // stop broadcast schedule
         fhss_structure->ws->is_on_bc_channel = false;
         fhss_structure->ws->synchronization_time = 0;
+        fhss_structure->ws->broadcast_timer_running = false;
         return;
     }
     if (fhss_structure->ws->is_on_bc_channel == false) {
@@ -479,6 +480,7 @@ static int16_t fhss_ws_synch_state_set_callback(const fhss_api_t *api, fhss_stat
         // Start broadcast schedule when BC intervals are known
         if (fhss_broadcast_interval && fhss_bc_dwell_interval) {
             fhss_broadcast_handler(fhss_structure->fhss_api, 0);
+            fhss_structure->ws->broadcast_timer_running = true;
         }
         // Start unicast schedule
         if ((fhss_structure->ws->fhss_configuration.ws_uc_channel_function != WS_FIXED_CHANNEL)) {
@@ -491,6 +493,7 @@ static int16_t fhss_ws_synch_state_set_callback(const fhss_api_t *api, fhss_stat
         eventOS_callback_timer_stop(fhss_structure->fhss_event_timer);
         fhss_stop_timer(fhss_structure, fhss_unicast_handler);
         fhss_stop_timer(fhss_structure, fhss_broadcast_handler);
+        fhss_structure->ws->broadcast_timer_running = false;
     }
 
     fhss_structure->fhss_state = fhss_state;
@@ -853,8 +856,13 @@ static uint32_t fhss_ws_get_retry_period_callback(const fhss_api_t *api, uint8_t
     if (!fhss_structure) {
         return return_value;
     }
+    // We don't know the broadcast schedule, use large backoff with MAC retries
+    if (fhss_structure->ws->broadcast_timer_running == false) {
+        return 100000;
+    }
+    // We don't know the TX/RX slots, use randomised large backoff with MAC retries
     if (fhss_structure->own_hop == 0xff) {
-        return return_value;
+        return ((uint32_t) randLIB_get_random_in_range(50, 150) * 1000);
     }
     if (fhss_structure->ws->is_on_bc_channel == true) {
         return return_value;
@@ -955,6 +963,7 @@ int fhss_ws_set_parent(fhss_structure_t *fhss_structure, const uint8_t eui64[8],
         timeout -= MS_TO_US(bc_timing_info->broadcast_interval - bc_timing_info->broadcast_dwell_interval);
     }
     fhss_ws_start_timer(fhss_structure, timeout, fhss_broadcast_handler);
+    fhss_structure->ws->broadcast_timer_running = true;
     uint16_t slots_since_reception = (bc_timing_info->broadcast_interval_offset + time_from_reception_ms) / bc_timing_info->broadcast_interval;
     // TODO: Calculate drift error
     fhss_structure->ws->fhss_configuration.fhss_bc_dwell_interval = bc_timing_info->broadcast_dwell_interval;

source/Service_Libs/fhss/fhss_ws.h

@@ -41,6 +41,7 @@ struct fhss_ws {
     int16_t *tr51_channel_table;
     uint8_t *tr51_output_table;
     bool unicast_timer_running;
+    bool broadcast_timer_running;
     bool is_on_bc_channel;
     struct fhss_ws_configuration fhss_configuration;
     const struct broadcast_timing_info *parent_bc_info;