MAC: Do not update framecounter for fhss channel retry

- Unless something was already sent after failure

Author: Jarkko Paso

source/MAC/IEEE802_15_4/mac_mcps_sap.c

@@ -1520,13 +1520,16 @@ static int8_t mcps_generic_packet_build(protocol_interface_rf_mac_setup_s *rf_pt
 
     if (buffer->fcf_dsn.securityEnabled) {
         //Remember to update security counter here!
-        buffer->aux_header.frameCounter = mac_mlme_framecounter_get(rf_ptr);
+        uint32_t new_frameCounter = mac_mlme_framecounter_get(rf_ptr);
+        // If buffer frame counter is set, this is FHSS channel retry, update frame counter only if something was sent after failure
+        if (!buffer->aux_header.frameCounter || ((new_frameCounter - buffer->aux_header.frameCounter) > 1)) {
+            buffer->aux_header.frameCounter = new_frameCounter;
+            //Increment security counter
+            mac_mlme_framecounter_increment(rf_ptr);
+        }
         if (!mac_frame_security_parameters_init(&ccm_ptr, rf_ptr, buffer)) {
             return -2;
         }
-        //Increment security counter
-        mac_mlme_framecounter_increment(rf_ptr);
-
     }
 
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