Contiki:使用 Rime 打印接收到的数据

Question

如何在recv_uc 函数中打印接收到的数据？在这种情况下是 var 的值。我使用 packetbuf_copyfrom(&var, 5) 将 var 放入发送的数据包中。

PROCESS(sending_rand, "Sending rand");
AUTOSTART_PROCESSES(&sending_rand);

static void
recv_uc(struct unicast_conn *c, const rimeaddr_t *from)
{
    printf("unicast message received from %d.%d\nreceived data: %d\n",
            from->u8[0], from->u8[1], /* print data received */);
}

static const struct unicast_callbacks unicast_call = {recv_uc};
static struct unicast_conn unicast;

PROCESS_THREAD(sending_rand, ev, data)
{
    static struct etimer et;//oggetto di tipo etimer
    int var;  

    PROCESS_EXITHANDLER(unicast_close(&unicast);)

    PROCESS_BEGIN();

    unicast_open(&unicast, 129, &unicast_call);

    while(1) {

        /* Delay 2-4 seconds */
        etimer_set(&et, CLOCK_SECOND * 4 + random_rand() % (CLOCK_SECOND * 4));

        PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et));

        var = random_rand();

        packetbuf_copyfrom(&var, 5);
        addr.u8[0] = 1;
        addr.u8[1] = 0;
        if(!rimeaddr_cmp(&addr, &rimeaddr_node_addr)) {
            unicast_send(&unicast, &addr);
        }

        printf("unicast message sent\n");
    }

    PROCESS_END();
}

Answer 1

一种方法是使用packetbuf_dataptr() 函数来访问内容。

int var;
memcpy(&var, packetbuf_dataptr(), sizeof(var));
printf("var=%d\n", var);

您的发送代码有一个与 var 的大小有关的错误。它是 2、4 或 8 个字节，具体取决于平台。它永远不会是 5，所以这是错误的:

packetbuf_copyfrom(&var, 5); // Undefined behavior!

如果大小很重要，请始终使用 int16_t/uint16_t 或 int32_t/uint32_t!它们在有效地包含在每个 Contiki 文件中的 header 中是类型定义的。