基于Raspberry Pi Pico+SX1262实现LoRaWAN Class C的技术问询

• 硬件配置：Raspberry Pi Pico 搭配 SX1262 LoRa扩展板
• 当前状态：已基于Waveshare的Class A OTAA示例代码实现定时发送功能，且在TTN（欧洲频段863-870MHz，LoRaWAN 1.0.2）完成Class A设备注册
• 需求：升级为同时支持定时发送与持续接收，根据LoRaWAN规范需采用Class C模式（除发送时段外，始终保持接收窗口打开）
• 问题：已在TTN注册时切换为Class C设备，但修改原Class A代码后，仅能实现类似Class B的延长接收窗口效果，无法达到Class C的持续监听要求
• 疑问：
  1. 如何通过代码实现真正的Class C模式？有没有可用的Class C参考代码？
  2. TTN的Class C设备注册流程是否正确？

#include <stdio.h>
#include <string.h>

#include "pico/stdlib.h"
#include "pico/lorawan.h"
#include "tusb.h"

// Edit with LoRaWAN Node Region and OTAA settings
#include "config.h"

// Pin configuration for SX1276 radio module
const struct lorawan_sx1276_settings sx1276_settings = {
    .spi = {
        .inst = PICO_DEFAULT_SPI_INSTANCE,
        .mosi = PICO_DEFAULT_SPI_TX_PIN,
        .miso = PICO_DEFAULT_SPI_RX_PIN,
        .sck  = PICO_DEFAULT_SPI_SCK_PIN,
        .nss  = 8
    },
    .reset = 9,
    .dio0  = 7,
    .dio1  = 10
};

// OTAA settings
const struct lorawan_otaa_settings otaa_settings = {
    .device_eui   = LORAWAN_DEVICE_EUI,
    .app_eui      = LORAWAN_APP_EUI,
    .app_key      = LORAWAN_APP_KEY,
    .channel_mask = LORAWAN_CHANNEL_MASK
};

// Variables for receiving data
int receive_length = 0;
uint8_t receive_buffer[242];
uint8_t receive_port = 0;

int main( void )
{
    // Initialize stdio and wait for USB CDC connect
    stdio_init_all();

    while (!tud_cdc_connected()) {
        tight_loop_contents();
    }

    printf("Pico LoRaWAN - Hello OTAA\n\n");

    // Uncomment the following line to enable debugging
    // lorawan_debug(true);

    // Initialize the LoRaWAN stack
    printf("Initilizating LoRaWAN ... ");
    if (lorawan_init_otaa(&sx1276_settings, LORAWAN_REGION, &otaa_settings) < 0) {
        printf("failed!!!\n");
        while (1) {
            tight_loop_contents();
        }
    } else {
        printf("success!\n");
    }

    // Start the join process and wait
    printf("Joining LoRaWAN network ... ");
    lorawan_join();

    while (!lorawan_is_joined()) {
        lorawan_process();
    }
    printf("joined successfully!\n");

    uint32_t last_message_time = 0;

    // Loop forever
    while (1) {
        // Let the LoRaWAN library process pending events
        lorawan_process();

        // Get the current time and see if 5 seconds have passed
        // since the last message was sent
        uint32_t now = to_ms_since_boot(get_absolute_time());

        if ((now - last_message_time) > 5000) {
            const char* message = "hello world!";

            // Try to send an unconfirmed uplink message
            printf("sending unconfirmed message '%s' ... ", message);
            if (lorawan_send_unconfirmed(message, strlen(message), 2) < 0) {
                printf("failed!!!\n");
            } else {
                printf("success!\n");
            }

            last_message_time = now;
        }

        // Check if a downlink message was received
        receive_length = lorawan_receive(receive_buffer, sizeof(receive_buffer), &receive_port);
        if (receive_length > -1) {
            printf("received a %d byte message on port %d: ", receive_length, receive_port);

            for (int i = 0; i < receive_length; i++) {
                printf("%02x", receive_buffer[i]);
            }
            printf("\n");
        }
    }

    return 0;
}

内容的提问来源于stack exchange，提问作者frabbit