Added Spectral Scan Feature

1 files changed, 540 insertions, 11 deletions

diff --git a/lora_pkt_fwd/src/lora_pkt_fwd.c b/lora_pkt_fwd/src/lora_pkt_fwd.c
index ca19e28..6665964 100644
--- a/lora_pkt_fwd/src/lora_pkt_fwd.c
+++ b/lora_pkt_fwd/src/lora_pkt_fwd.c
@@ -45,6 +45,8 @@ Maintainer: Michael Coracin
 #include <arpa/inet.h>      /* IP address conversion stuff */
 #include <netdb.h>          /* gai_strerror */
 
+#include <spawn.h>
+#include <sys/wait.h>
 #include <pthread.h>
 
 #include "trace.h"
@@ -56,6 +58,8 @@ Maintainer: Michael Coracin
 #include "loragw_gps.h"
 #include "loragw_aux.h"
 #include "loragw_reg.h"
+#include "loragw_radio.h"
+#include "loragw_fpga.h"
 
 /* -------------------------------------------------------------------------- */
 /* --- PRIVATE MACROS ------------------------------------------------------- */
@@ -93,6 +97,7 @@ Maintainer: Michael Coracin
 #define PKT_PULL_RESP   3
 #define PKT_PULL_ACK    4
 #define PKT_TX_ACK      5
+#define PKT_SPEC_SCAN   6
 
 #define NB_PKT_MAX      8 /* max number of packets per fetch/send cycle */
 
@@ -101,12 +106,11 @@ Maintainer: Michael Coracin
 #define MIN_FSK_PREAMB  3 /* minimum FSK preamble length for this application */
 #define STD_FSK_PREAMB  5
 
-#define STATUS_SIZE     200
+#define STATUS_SIZE     50000
 #define TX_BUFF_SIZE    ((540 * NB_PKT_MAX) + 30 + STATUS_SIZE)
 
 #define UNIX_GPS_EPOCH_OFFSET 315964800 /* Number of seconds ellapsed between 01.Jan.1970 00:00:00
                                                                           and 06.Jan.1980 00:00:00 */
-
 #define DEFAULT_BEACON_FREQ_HZ      869525000
 #define DEFAULT_BEACON_FREQ_NB      1
 #define DEFAULT_BEACON_FREQ_STEP    0
@@ -115,6 +119,29 @@ Maintainer: Michael Coracin
 #define DEFAULT_BEACON_POWER        14
 #define DEFAULT_BEACON_INFODESC     0
 
+#define DEFAULT_START               867000000   /* start frequency, Hz */
+#define DEFAULT_STOP                870000000   /* stop frequency, Hz */
+#define DEFAULT_STEP                1000000      /* frequency step, Hz */
+#define DEFAULT_SAMPLES             65535       /* number of RSSI reads */
+#define DEFAULT_CHAN_BW             LGW_SX127X_RXBW_62K5_HZ /* channel bandwidth */
+#define DEFAULT_SX127X_RSSI_OFFSET  -120
+
+#define RSSI_RANGE                  256
+
+#define MAX_FREQ                    1000000000
+#define MIN_FREQ                    800000000
+#define MIN_step                    5000
+
+#define FPGA_FEATURE_SPECTRAL_SCAN  1
+#define FPGA_FEATURE_LBT            2
+
+/* When FPGA supports LBT, there are few more constraints on above constants */
+#define LBT_DEFAULT_SAMPLES         129*129 /* number of RSSI reads, hard-coded in FPGA*/
+#define LBT_MIN_STEP                100000
+
+#define HISTOGRAM_CLEAN_TIMEOUT     10000
+#define HISTOGRAM_READY_TIMEOUT     1000
+
 /* -------------------------------------------------------------------------- */
 /* --- PRIVATE VARIABLES (GLOBAL) ------------------------------------------- */
 
@@ -209,6 +236,25 @@ static struct coord_s meas_gps_err; /* GPS position of the gateway */
 static pthread_mutex_t mx_stat_rep = PTHREAD_MUTEX_INITIALIZER; /* control access to the status report */
 static bool report_ready = false; /* true when there is a new report to send to the server */
 static char status_report[STATUS_SIZE]; /* status report as a JSON object */
+static char serialized_string[STATUS_SIZE];
+
+/* spectral scan parameters */
+static pthread_mutex_t mx_scan_config = PTHREAD_MUTEX_INITIALIZER; /* control access to the spectral scan config */
+static pthread_mutex_t mx_scan_report = PTHREAD_MUTEX_INITIALIZER; /* control access to the spectral scan config */
+static bool scan_ready = false; /* true when there is a new report to send to the server */
+
+struct scan_config_s
+{
+    uint32_t init;
+    uint32_t start;
+    uint32_t stop;
+    uint32_t step;
+    uint16_t samples;
+    int8_t rssi_floor;
+    int8_t offset;
+    uint32_t bandwidth;
+    bool read;
+} scan_config, scan_config_new, scan_config_update;
 
 /* beacon parameters */
 static uint32_t beacon_period = 0; /* set beaconing period, must be a sub-multiple of 86400, the nb of sec in a day */
@@ -258,10 +304,139 @@ void thread_gps(void);
 void thread_valid(void);
 void thread_jit(void);
 void thread_timersync(void);
+void thread_spectralscan(void);
 
 /* -------------------------------------------------------------------------- */
 /* --- PRIVATE FUNCTIONS DEFINITION ----------------------------------------- */
 
+static enum lgw_sx127x_rxbw_e map_bandwidth(uint32_t bandwidth) {
+    switch (bandwidth) {
+        case 25:
+            return LGW_SX127X_RXBW_12K5_HZ;
+        case 50:
+            return LGW_SX127X_RXBW_25K_HZ;
+        case 100:
+            return LGW_SX127X_RXBW_50K_HZ;
+        case 125:
+            return LGW_SX127X_RXBW_62K5_HZ;
+        case 200:
+            return LGW_SX127X_RXBW_100K_HZ;
+        case 250:
+            return LGW_SX127X_RXBW_125K_HZ;
+        case 500:
+            return LGW_SX127X_RXBW_250K_HZ;
+        default:
+            printf("ERROR: Failed to parse spectral scan bandwidth.\n");
+            return EXIT_FAILURE;
+    }
+}
+
+static int reset_fpga(bool lbt_support, uint16_t samples) {
+    int x;
+    /* Reconnect to FPGA with sw reset and configure */
+    x = lgw_disconnect();
+    if(x != 0) {
+        printf("ERROR: Failed to disconnect from FPGA\n");
+        return EXIT_FAILURE;
+    }
+    x = lgw_connect(false, LGW_DEFAULT_NOTCH_FREQ); /* FPGA reset/configure */
+    if(x != 0) {
+        printf("ERROR: Failed to connect to FPGA\n");
+        return EXIT_FAILURE;
+    }
+    if (lbt_support == false) {
+        x = lgw_fpga_reg_w(LGW_FPGA_HISTO_NB_READ, samples-1);
+        if( x != LGW_REG_SUCCESS )
+        {
+            printf( "ERROR: Failed to configure FPGA\n" );
+            return EXIT_FAILURE;
+        }
+    }
+    return EXIT_SUCCESS;
+}
+
+static int setup_spectral_scan(bool *lbt_support, uint64_t *freq_reg, uint32_t *freq_nb) {
+
+    int x; /* return code for functions */
+    int32_t reg_val;
+
+    /* Check if FPGA supports Spectral Scan */
+    lgw_fpga_reg_r(LGW_FPGA_FEATURE, &reg_val);
+    if (TAKE_N_BITS_FROM((uint8_t)reg_val, FPGA_FEATURE_SPECTRAL_SCAN, 1) != true) {
+        printf("ERROR: Spectral Scan is not supported (0x%x)\n", (uint8_t)reg_val);
+        return EXIT_FAILURE;
+    }
+
+    /* Check if FPGA supports LBT, in order to apply proper constraints on spectral scan parameters */
+    lgw_fpga_reg_r(LGW_FPGA_FEATURE, &reg_val);
+
+    if (TAKE_N_BITS_FROM((uint8_t)reg_val, FPGA_FEATURE_LBT, 1) == true) {
+        printf("WARNING: The FPGA supports LBT, so running spectral scan with specific constraints\n");
+        printf("         => Check the parameters summary below\n");
+        /* Get start frequency from FPGA */
+        lgw_fpga_reg_r(LGW_FPGA_LBT_INITIAL_FREQ, &reg_val);
+        switch (reg_val) {
+            case 0:
+                scan_config.init = 915000000;
+                break;
+            case 1:
+                scan_config.init = 863000000;
+                break;
+            default:
+                printf("ERROR: init frequency %d is not supported\n", reg_val);
+                return EXIT_FAILURE;
+        }
+
+        /* Check parameters based on LBT constraints */
+        if (scan_config.start < scan_config.init) {
+            printf("ERROR: start frequency %d is not supported, should be >=%d\n", scan_config.start, scan_config.init);
+            return EXIT_FAILURE;
+        }
+        if (scan_config.stop > (scan_config.init + 255*LBT_MIN_STEP)) {
+            printf("ERROR: stop frequency %d is not supported, should be <%d\n", scan_config.stop, scan_config.init + 255*LBT_MIN_STEP);
+            return EXIT_FAILURE;
+        }
+        if (scan_config.step < LBT_MIN_STEP) {
+            printf("ERROR: step frequency %d is not supported, should be >=%d\n", scan_config.step, LBT_MIN_STEP);
+            return EXIT_FAILURE;
+        } else {
+            /* Ensure the given step is a multiple of LBT_MIN_STEP */
+            scan_config.step = (scan_config.step / LBT_MIN_STEP) * LBT_MIN_STEP;
+        }
+
+        /* Overload hard-coded spectral scan parameters */
+        scan_config.samples = LBT_DEFAULT_SAMPLES;
+
+        /* Spectral scan sequence is slightly different depending if LBT is there or not */
+        *lbt_support = true;
+    } else {
+        /* Reconnect to FPGA with sw reset and configure */
+        x = lgw_disconnect();
+        if(x != 0) {
+            printf("ERROR: Failed to disconnect from FPGA\n");
+            return EXIT_FAILURE;
+        }
+        x = lgw_connect(false, LGW_DEFAULT_NOTCH_FREQ); /* FPGA reset/configure */
+        if(x != 0) {
+            printf("ERROR: Failed to connect to FPGA\n");
+            return EXIT_FAILURE;
+        }
+        /* Some spectral scan options are only available when there is no LBT support */
+        x = lgw_fpga_reg_w(LGW_FPGA_HISTO_NB_READ, scan_config.samples-1);
+        if( x != LGW_REG_SUCCESS )
+        {
+            printf( "ERROR: Failed to configure FPGA\n" );
+            return EXIT_FAILURE;
+        }
+
+        /* Initialize frequency */
+        *freq_reg = ((uint64_t)scan_config.start << 19) / (uint64_t)32000000;
+        lgw_fpga_reg_w(LGW_FPGA_HISTO_SCAN_FREQ, (int32_t)freq_reg);
+    }
+    *freq_nb = (uint32_t)((scan_config.stop - scan_config.start) / scan_config.step) + 1;
+    return 0;
+}
+
 static void sig_handler(int sigio) {
     if (sigio == SIGQUIT) {
         quit_sig = true;
@@ -992,7 +1167,6 @@ int main(void)
     char *global_cfg_path= "global_conf.json"; /* contain global (typ. network-wide) configuration */
     char *local_cfg_path = "local_conf.json"; /* contain node specific configuration, overwrite global parameters for parameters that are defined in both */
     char *debug_cfg_path = "debug_conf.json"; /* if present, all other configuration files are ignored */
-
     /* threads */
     pthread_t thrid_up;
     pthread_t thrid_down;
@@ -1000,6 +1174,7 @@ int main(void)
     pthread_t thrid_valid;
     pthread_t thrid_jit;
     pthread_t thrid_timersync;
+    pthread_t thrid_spectralscan;
 
     /* network socket creation */
     struct addrinfo hints;
@@ -1249,6 +1424,13 @@ int main(void)
         }
     }
 
+    i = pthread_create( &thrid_spectralscan, NULL, (void * (*)(void *))thread_spectralscan, NULL);
+    if (i != 0) {
+        MSG("ERROR: [main] impossible to create spectral scan thread\n");
+        exit(EXIT_FAILURE);
+    }
+
+
     /* configure signal handling */
     sigemptyset(&sigact.sa_mask);
     sigact.sa_flags = 0;
@@ -1435,6 +1617,8 @@ int main(void)
         }
     }
 
+    pthread_join(thrid_spectralscan, NULL); /* don't wait for spec scan thread */
+
     /* if an exit signal was received, try to quit properly */
     if (exit_sig) {
         /* shut down network sockets */
@@ -1852,6 +2036,20 @@ void thread_up(void) {
                 exit(EXIT_FAILURE);
             }
         }
+        if (scan_ready == true) {
+            pthread_mutex_lock(&mx_scan_report);
+            j = snprintf((char *)(buff_up + buff_index), TX_BUFF_SIZE-buff_index, ",\"spectral_scan\":%s", serialized_string);
+            scan_ready = false;
+            pthread_mutex_unlock(&mx_scan_report);
+            if (j > 0) {
+                buff_index += j;
+            } else {
+                MSG("ERROR: [up] snprintf failed line %u\n", (__LINE__ - 5));
+                exit(EXIT_FAILURE);
+            }
+        } else {
+            pthread_mutex_unlock(&mx_scan_report);
+        }
 
         /* end of JSON datagram payload */
         buff_up[buff_index] = '}';
@@ -1921,6 +2119,7 @@ void thread_down(void) {
     /* JSON parsing variables */
     JSON_Value *root_val = NULL;
     JSON_Object *txpk_obj = NULL;
+    JSON_Object *specscan_obj = NULL;
     JSON_Value *val = NULL; /* needed to detect the absence of some fields */
     const char *str; /* pointer to sub-strings in the JSON data */
     short x0, x1;
@@ -2212,7 +2411,7 @@ void thread_down(void) {
             }
 
             /* if the datagram does not respect protocol, just ignore it */
-            if ((msg_len < 4) || (buff_down[0] != PROTOCOL_VERSION) || ((buff_down[3] != PKT_PULL_RESP) && (buff_down[3] != PKT_PULL_ACK))) {
+            if ((msg_len < 4) || (buff_down[0] != PROTOCOL_VERSION) || ((buff_down[3] != PKT_PULL_RESP) && (buff_down[3] != PKT_PULL_ACK) && (buff_down[3] != PKT_SPEC_SCAN))) {
                 MSG("WARNING: [down] ignoring invalid packet len=%d, protocol_version=%d, id=%d\n",
                         msg_len, buff_down[0], buff_down[3]);
                 continue;
@@ -2236,11 +2435,12 @@ void thread_down(void) {
                 }
                 continue;
             }
-
-            /* the datagram is a PULL_RESP */
-            buff_down[msg_len] = 0; /* add string terminator, just to be safe */
-            MSG("INFO: [down] PULL_RESP received  - token[%d:%d] :)\n", buff_down[1], buff_down[2]); /* very verbose */
-            printf("\nJSON down: %s\n", (char *)(buff_down + 4)); /* DEBUG: display JSON payload */
+            if (buff_down[3] == PKT_PULL_RESP || buff_down[3] == PKT_SPEC_SCAN) {
+                /* the datagram is a PULL_RESP */
+                buff_down[msg_len] = 0; /* add string terminator, just to be safe */
+                MSG("INFO: [down] PULL_RESP received  - token[%d:%d] :)\n", buff_down[1], buff_down[2]); /* very verbose */
+                printf("\nJSON down: %s\n", (char *)(buff_down + 4)); /* DEBUG: display JSON payload */
+            }
 
             /* initialize TX struct and try to parse JSON */
             memset(&txpkt, 0, sizeof txpkt);
@@ -2252,12 +2452,68 @@ void thread_down(void) {
 
             /* look for JSON sub-object 'txpk' */
             txpk_obj = json_object_get_object(json_value_get_object(root_val), "txpk");
-            if (txpk_obj == NULL) {
-                MSG("WARNING: [down] no \"txpk\" object in JSON, TX aborted\n");
+            specscan_obj = json_object_get_object(json_value_get_object(root_val), "scan");
+            if (txpk_obj == NULL && specscan_obj == NULL) {
+                MSG("WARNING: [down] no \"txpk\" or \"scan\"object in JSON, TX aborted\n");
                 json_value_free(root_val);
                 continue;
             }
+            if (specscan_obj != NULL) {
+                bool valid_config = true;
+                val = json_object_get_value(specscan_obj, "start"); /* fetch value (if possible) */
+                if (json_value_get_type(val) == JSONNumber) {
+                    scan_config_update.start = (uint32_t)json_value_get_number(val);
+                } else {
+                    MSG("INFO: [down] start is not a number, ignoring scan config\n");
+                    valid_config = false;
+                }
+                val = json_object_get_value(specscan_obj, "stop"); /* fetch value (if possible) */
+                if (json_value_get_type(val) == JSONNumber) {
+                    scan_config_update.stop = (uint32_t)json_value_get_number(val);
+                } else {
+                    MSG("INFO: [down] stop is not a number, ignoring scan config\n");
+                    valid_config = false;
+                }
+                val = json_object_get_value(specscan_obj, "step"); /* fetch value (if possible) */
+                if (json_value_get_type(val) == JSONNumber) {
+                    scan_config_update.step = (uint32_t)json_value_get_number(val);
+                } else {
+                    MSG("INFO: [down] step is not a number, ignoring scan config\n");
+                    valid_config = false;
+                }
+                val = json_object_get_value(specscan_obj, "samples"); /* fetch value (if possible) */
+                if (json_value_get_type(val) == JSONNumber) {
+                    scan_config_update.samples = (uint32_t)json_value_get_number(val);
+                } else {
+                    MSG("INFO: [down] step is not a number, ignoring scan config\n");
+                    valid_config = false;
+                }
+                val = json_object_get_value(specscan_obj, "offset"); /* fetch value (if possible) */
+                if (json_value_get_type(val) == JSONNumber) {
+                    scan_config_update.offset = (uint32_t)json_value_get_number(val);
+                } else {
+                    MSG("INFO: [down] step is not a number, ignoring scan config\n");
+                    valid_config = false;
+                }
+                val = json_object_get_value(specscan_obj, "bandwidth"); /* fetch value (if possible) */
+                if (json_value_get_type(val) == JSONNumber) {
+                    scan_config_update.bandwidth = (uint32_t)json_value_get_number(val);
+                } else {
+                    MSG("INFO: [down] bandwidth is not a number, ignoring scan config\n");
+                    valid_config = false;
+                }
+                scan_config_update.read = false;
 
+                pthread_mutex_lock(&mx_scan_config);
+                if (valid_config) {
+                    scan_config_new = scan_config_update;
+                }
+                pthread_mutex_unlock(&mx_scan_config);
+
+            }
+            if (txpk_obj == NULL) {
+                continue;
+            }
             /* Parse "immediate" tag, or target timestamp, or UTC time to be converted by GPS (mandatory) */
             i = json_object_get_boolean(txpk_obj,"imme"); /* can be 1 if true, 0 if false, or -1 if not a JSON boolean */
             if (i == 1) {
@@ -2893,4 +3149,277 @@ void thread_valid(void) {
     MSG("\nINFO: End of validation thread\n");
 }
 
+/* -------------------------------------------------------------------------- */
+/* --- THREAD 6: Spectral Scan --- */
+
+void thread_spectralscan(void) {
+    struct timeval tv;
+    /* Application parameters */
+    uint16_t i, j, k; /* loop and temporary variables */
+    int x; /* return code for functions */
+    int32_t reg_val;
+
+    /* Application parameters */
+
+    /* Local var */
+    bool lbt_support = false;
+    uint16_t histogram_clean_retry = 0;
+    uint16_t histogram_ready_retry = 0;
+    uint16_t histogram_clean_counter = 0;
+    uint16_t histogram_ready_counter = 0;
+    uint16_t retry_limit = 1500;
+    int freq_idx;
+    uint32_t freq_nb;
+    int old_min = -1;
+    uint64_t freq_reg;
+    uint32_t freq;
+    uint8_t read_burst[RSSI_RANGE*2];
+    uint16_t rssi_histo;
+    uint16_t rssi_cumu;
+    uint32_t reset_counter_a = 0;
+    uint32_t reset_counter_b = 0;
+    scan_config.init = DEFAULT_START;
+    scan_config.start = DEFAULT_START;
+    scan_config.stop = DEFAULT_STOP;
+    scan_config.step = DEFAULT_STEP;
+    scan_config.samples = DEFAULT_SAMPLES;
+    scan_config.offset = DEFAULT_SX127X_RSSI_OFFSET;
+    scan_config.bandwidth = 0;
+    scan_config.read = true;
+    pthread_mutex_lock(&mx_scan_config);
+    scan_config_new = scan_config;
+    pthread_mutex_unlock(&mx_scan_config);
+
+    while (!exit_sig && !quit_sig) {
+        gettimeofday(&tv, NULL);
+        // Form the seconds of the day
+        long hms = tv.tv_sec % 86400;
+        // int hour = hms / 3600;
+        int min = (hms % 3600) / 60;
+        // int sec = (hms % 3600) % 60; // or hms % SEC_PER_MIN
+        pthread_mutex_lock(&mx_scan_config);
+        if (scan_config_new.read == false) {
+            scan_config = scan_config_new;
+            scan_config_new.read = true;
+        }
+        pthread_mutex_unlock(&mx_scan_config);
+        if (scan_config.read == false) {
+            /* Main loop */
+            setup_spectral_scan(&lbt_support, &freq_reg, &freq_nb);
+            JSON_Value *root_value = json_value_init_object();
+            JSON_Object *root_object = json_value_get_object(root_value);
+            JSON_Array *interests_arr = NULL;
+            json_object_set_number(root_object, "bandwidth", scan_config.bandwidth);
+            char eui[17];
+            sprintf(&eui[0], "%016lX", lgwm);
+            json_object_set_string(root_object, "eui", eui);
+            json_object_set_value(root_object, "results", json_value_init_array());
+            interests_arr = json_object_get_array(root_object, "results");
+            json_object_set_number(root_object, "start", scan_config.start);
+            json_object_set_number(root_object, "stop", scan_config.stop);
+            json_object_set_number(root_object, "step", scan_config.step);
+            json_object_set_number(root_object, "floor", -160);
+            json_object_set_number(root_object, "offset", scan_config.offset);
+            json_object_set_number(root_object, "samples", scan_config.samples);
+
+            struct timespec t1;
+            time_t t;
+            t = time(NULL);
+            clock_gettime(CLOCK_MONOTONIC, &t1);
+            char scan_timestamp[24];
+            strftime(scan_timestamp, sizeof scan_timestamp, "%F %T %Z", gmtime(&t));
+            json_object_set_string(root_object, "time", scan_timestamp);
+            for(j = 0; j < freq_nb; j++) {
+                /* Current frequency */
+                if (exit_sig || quit_sig) exit(EXIT_FAILURE);
+                freq = scan_config.start + j * scan_config.step;
+                struct timespec t2;
+                clock_gettime(CLOCK_MONOTONIC, &t2);
+
+                // double scan_time = difftimespec(t2, t1);
+                int scan_time = (int)(1000 * difftimespec(t2, t1));
+                if (lbt_support == false) {
+                    /* Set SX127x */
+                    x = lgw_setup_sx127x(freq, MOD_FSK, map_bandwidth(scan_config.bandwidth), 0);
+                    if( x != 0 ) {
+                        MSG( "ERROR: SX127x setup failed\n" );
+                        exit(EXIT_FAILURE);
+                    }
+
+                    /* Start FPGA state machine for spectral scal */
+                    lgw_fpga_reg_w(LGW_FPGA_CTRL_FEATURE_START, 1);
+                } else {
+                    /* Do Nothing */
+                    /* LBT setup has already done the necessary */
+                }
+
+                /* Clean histogram */
+                lgw_fpga_reg_w(LGW_FPGA_CTRL_CLEAR_HISTO_MEM, 1);
+                uint8_t reg_stat_old = 255;
+                uint8_t reg_stat_new;
+                /* Wait for histogram clean to start */
+                do {
+                    if (histogram_clean_counter > HISTOGRAM_CLEAN_TIMEOUT) {
+                        reg_stat_new = reg_val;
+                        reg_stat_old = reg_stat_new;
+                        if (histogram_clean_retry >= retry_limit) {
+                            printf("\nHistogram clean retry limit reached.");
+                            exit(EXIT_FAILURE);
+                        } else {
+                            reset_counter_a++;
+                            printf(" - ERROR: Histogram clean timed out! Resetting FPGA and trying again\n");
+                            lgw_stop();
+                            lgw_start();
+                            x = reset_fpga(lbt_support, scan_config.samples);
+                            setup_spectral_scan(&lbt_support, &freq_reg, &freq_nb);
+                            if( x != 0 ) {
+                                printf( "ERROR: SX127x reset failed\n" );
+                            }
+                            lgw_fpga_reg_w(LGW_FPGA_CTRL_CLEAR_HISTO_MEM, 1);
+                            if (lbt_support == false) {
+                                x = lgw_setup_sx127x(freq, MOD_FSK, map_bandwidth(scan_config.bandwidth), 0);
+                                if( x != 0 ) {
+                                    printf( "ERROR: SX127x setup failed\n" );
+                                    return EXIT_FAILURE;
+                                }
+                                lgw_fpga_reg_w(LGW_FPGA_CTRL_FEATURE_START, 1);
+                            }
+                            histogram_clean_counter = 0;
+                            histogram_clean_retry++;
+                        }
+                    }
+                    wait_ms(10);
+                    lgw_fpga_reg_r(LGW_FPGA_STATUS, &reg_val);
+                    histogram_clean_counter++;
+                }
+                while((TAKE_N_BITS_FROM((uint8_t)reg_val, 0, 5)) != 1); /* Clear has started */
+
+                /* Set scan frequency during clear process */
+                if (lbt_support == false) {
+                    /* We can directly set the scan frequency */
+                    freq_reg = ((uint64_t)freq << 19) / (uint64_t)32000000;
+                    lgw_fpga_reg_w(LGW_FPGA_HISTO_SCAN_FREQ, (int32_t)freq_reg);
+                } else {
+                    /* The possible scan frequencies are hard-coded in FPGA, we give an offset from init */
+                    freq_idx = (freq - scan_config.init) / LBT_MIN_STEP;
+                    lgw_fpga_reg_w(LGW_FPGA_SCAN_FREQ_OFFSET, freq_idx);
+                }
+
+                /* Release FPGA state machine */
+                lgw_fpga_reg_w(LGW_FPGA_CTRL_CLEAR_HISTO_MEM, 0);
+
+                /* Wait for histogram ready */
+                do {
+                    if (histogram_ready_counter > HISTOGRAM_READY_TIMEOUT) {
+                        if (histogram_ready_retry >= retry_limit) {
+                            MSG("\nHistogram timeout retry limit reached");
+                            lgw_stop();
+                            lgw_start();
+                            x = reset_fpga(lbt_support, scan_config.samples);
+                            setup_spectral_scan(&lbt_support, &freq_reg, &freq_nb);
+                        } else {
+                            reset_counter_b++;
+                            MSG("ERROR: Histogram ready timed out! Resetting FPGA and trying again\n");
+                            x = reset_fpga(lbt_support, scan_config.samples);
+                            setup_spectral_scan(&lbt_support, &freq_reg, &freq_nb);
+                            if( x != 0 ) {
+                                MSG( "ERROR: SX127x reset failed\n" );
+                                exit(EXIT_FAILURE);
+                            }
+                            lgw_fpga_reg_w(LGW_FPGA_CTRL_CLEAR_HISTO_MEM, 1);
+                            if (lbt_support == false) {
+                                x = lgw_setup_sx127x(freq, MOD_FSK, map_bandwidth(scan_config.bandwidth), 0);
+                                if( x != 0 ) {
+                                    MSG( "ERROR: SX127x setup failed\n" );
+                                    setup_spectral_scan(&lbt_support, &freq_reg, &freq_nb);
+                                }
+                                lgw_fpga_reg_w(LGW_FPGA_CTRL_FEATURE_START, 1);
+                            }
+                            histogram_ready_counter = 0;
+                            histogram_ready_retry++;
+                            if (lbt_support == false) {
+                                freq_reg = ((uint64_t)freq << 19) / (uint64_t)32000000;
+                                lgw_fpga_reg_w(LGW_FPGA_HISTO_SCAN_FREQ, (int32_t)freq_reg);
+                            } else {
+                                freq_idx = (freq - scan_config.init) / LBT_MIN_STEP;
+                                lgw_fpga_reg_w(LGW_FPGA_SCAN_FREQ_OFFSET, freq_idx);
+                            }
+                            lgw_fpga_reg_w(LGW_FPGA_CTRL_CLEAR_HISTO_MEM, 0);
+                        }
+                    }
+                    wait_ms(1000);
+                    lgw_fpga_reg_r(LGW_FPGA_STATUS, &reg_val);
+                    histogram_ready_counter++;
+                }
+                while((TAKE_N_BITS_FROM((uint8_t)reg_val, 5, 1)) != 1);
+
+                if (lbt_support == false) {
+                    /* Stop FPGA state machine for spectral scan */
+                    lgw_fpga_reg_w(LGW_FPGA_CTRL_FEATURE_START, 0);
+                } else {
+                    /* Do Nothing */
+                    /* LBT is running */
+                }
+
+                /* Read histogram */
+                lgw_fpga_reg_w(LGW_FPGA_CTRL_ACCESS_HISTO_MEM, 1); /* HOST gets access to FPGA RAM */
+                lgw_fpga_reg_w(LGW_FPGA_HISTO_RAM_ADDR, 0);
+                lgw_fpga_reg_rb(LGW_FPGA_HISTO_RAM_DATA, read_burst, RSSI_RANGE*2);
+                lgw_fpga_reg_w(LGW_FPGA_CTRL_ACCESS_HISTO_MEM, 0); /* FPGA gets access to RAM back */
+
+                rssi_cumu = 0;
+                k = 0;
+                char param_name[32];
+                char *seria_string = NULL;
+                JSON_Value *scan_value = json_value_init_object();
+                JSON_Object *scan_object = json_value_get_object(scan_value);
+                char scan_string[1024] = "";
+                snprintf(scan_string, sizeof scan_string, "%d, %d", freq, scan_time); 
+
+                float rssi_thresh[] = {0.1,0.3,0.5,0.8,1};
+                for (i = 0; i < RSSI_RANGE; i++) {
+                    rssi_histo = (uint16_t)read_burst[2*i] | ((uint16_t)read_burst[2*i+1] << 8);
+                    rssi_cumu += rssi_histo;
+                    if (rssi_cumu > scan_config.samples) {
+                        MSG("WARNING: number of RSSI points higher than expected (%u,%u)", rssi_cumu, scan_config.samples);
+                        rssi_cumu = scan_config.samples;
+                    }
+                    if (rssi_cumu > rssi_thresh[k]*scan_config.samples) {
+                        snprintf(param_name, sizeof param_name, "rssi_%d", (uint16_t)(rssi_thresh[k]*100)); 
+                        json_object_set_number(scan_object, param_name, -i/2.0);
+                        k++;
+                    }
+                    if (rssi_histo > 0) {
+                        char valid_hiso[1024] = "\"";
+                        snprintf(valid_hiso, sizeof valid_hiso, ",%.1f,%d", (-i/2.0), rssi_histo);
+                        strcat(scan_string, valid_hiso);
+                    }
+                }
+                json_array_append_string(interests_arr, scan_string);
+                json_free_serialized_string(seria_string);
+                json_value_free(scan_value);
+            }
+            char array_string[5000] = "[\"";
+            for (i = 0; i < json_array_get_count(interests_arr); i++) {
+                const char * v = json_array_get_string(interests_arr, i);
+                strcat(array_string, v);
+                if (i < json_array_get_count(interests_arr) - 1 ) {
+                    strcat(array_string,"\",\"");
+                }
+            }
+            strcat(array_string, "\"]");
+            json_object_set_value(root_object, "results",  json_parse_string(array_string));
+            old_min = min;
+
+            pthread_mutex_lock(&mx_scan_report);
+            scan_ready = true;
+            strcpy(serialized_string, json_serialize_to_string(root_value));
+            pthread_mutex_unlock(&mx_scan_report);
+            json_value_free(root_value);
+            scan_config.read = true;
+        }
+    }
+    MSG("\nINFO: End of spectral scan thread\n");
+}
+
 /* --- EOF ------------------------------------------------------------------ */