lora tx 代码分析

for (cnt_loop = 0; cnt_loop < nb_loop; cnt_loop++) {
        /* Board reset */
        if (system("./reset_lgw.sh start") != 0) {
            printf("ERROR: failed to reset SX1302, check your reset_lgw.sh script\n");
            exit(EXIT_FAILURE);
        }

        /* connect, configure and start the LoRa concentrator */
        x = lgw_start();
        if (x != 0) {
            printf("ERROR: failed to start the gateway\n");
            return EXIT_FAILURE;
        }

        /* Send packets */
        memset(&pkt, 0, sizeof pkt);
        pkt.rf_chain = rf_chain;
        pkt.freq_hz = ft;
        pkt.rf_power = rf_power;
        if (trig_delay == false) {
            pkt.tx_mode = IMMEDIATE;
        } else {
            if (trig_delay_us == 0) {
                pkt.tx_mode = ON_GPS;
            } else {
                pkt.tx_mode = TIMESTAMPED;
            }
        }
        if ( strcmp( mod, "CW" ) == 0 ) {
            pkt.modulation = MOD_CW;
            pkt.freq_offset = freq_offset;
            pkt.f_dev = fdev_khz;
        }
        else if( strcmp( mod, "FSK" ) == 0 ) {
            pkt.modulation = MOD_FSK;
            pkt.no_crc = false;
            pkt.datarate = br_kbps * 1e3;
            pkt.f_dev = fdev_khz;
        } else {
            pkt.modulation = MOD_LORA;
            pkt.coderate = CR_LORA_4_5;
            pkt.no_crc = true;
        }
        pkt.invert_pol = invert_pol;
        pkt.preamble = preamble;
        pkt.no_header = no_header;
        pkt.payload[0] = 0x40; /* Confirmed Data Up */
        pkt.payload[1] = 0xAB;
        pkt.payload[2] = 0xAB;
        pkt.payload[3] = 0xAB;
        pkt.payload[4] = 0xAB;
        pkt.payload[5] = 0x00; /* FCTrl */
        pkt.payload[6] = 0; /* FCnt */
        pkt.payload[7] = 0; /* FCnt */
        pkt.payload[8] = 0x02; /* FPort */
        for (i = 9; i < 255; i++) {
            pkt.payload[i] = i;
        }

        for (i = 0; i < (int)nb_pkt; i++) {
            if (trig_delay == true) {
                if (trig_delay_us > 0) {
                    lgw_get_instcnt(&count_us);
                    printf("count_us:%u\n", count_us);
                    pkt.count_us = count_us + trig_delay_us;
                    printf("programming TX for %u\n", pkt.count_us);
                } else {
                    printf("programming TX for next PPS (GPS)\n");
                }
            }

            if( strcmp( mod, "LORA" ) == 0 ) {
                pkt.datarate = (sf == 0) ? (uint8_t)RAND_RANGE(5, 12) : sf;
            }

            switch (bw_khz) {
                case 125:
                    pkt.bandwidth = BW_125KHZ;
                    break;
                case 250:
                    pkt.bandwidth = BW_250KHZ;
                    break;
                case 500:
                    pkt.bandwidth = BW_500KHZ;
                    break;
                default:
                    pkt.bandwidth = (uint8_t)RAND_RANGE(BW_125KHZ, BW_500KHZ);
                    break;
            }

            pkt.size = (size == 0) ? (uint8_t)RAND_RANGE(9, 255) : size;

            pkt.payload[6] = (uint8_t)(i >> 0); /* FCnt */
            pkt.payload[7] = (uint8_t)(i >> 8); /* FCnt */
            x = lgw_send(&pkt);
            if (x != 0) {
                printf("ERROR: failed to send packet\n");
                return EXIT_FAILURE;
            }
            /* wait for packet to finish sending */
            do {
                wait_ms(5);
                lgw_status(pkt.rf_chain, TX_STATUS, &tx_status); /* get TX status */
            } while ((tx_status != TX_FREE) && (quit_sig != 1) && (exit_sig != 1));

            if ((quit_sig == 1) || (exit_sig == 1)) {
                break;
            }
            printf("TX done\n");
        }

        printf( "\nNb packets sent: %u (%u)\n", i, cnt_loop + 1 );

        /* Stop the gateway */
        x = lgw_stop();
        if (x != 0) {
            printf("ERROR: failed to stop the gateway\n");
            return EXIT_FAILURE;
        }

        /* Board reset */
        if (system("./reset_lgw.sh stop") != 0) {
            printf("ERROR: failed to reset SX1302, check your reset_lgw.sh script\n");
            exit(EXIT_FAILURE);
        }
    }

    printf("=========== Test End ===========\n");