通过at_client组件设置AT指令，进入串口接收模式，+IPD后面的透传数据没有接收到；

发布于 2023-08-12 19:50:31 浏览：493 订阅该版

一、问题描述：
STM32F429作为at client，esp32c3作为 at server；
STM32F429通过at指令将esp32c3设置为透传模式，但是esp32c3发给STM32F429的透传数据，at client没有正常接收，
比如`+IPD,0,3:123`, at client 只接收了 `+IPD,0,3:` ,将透传数据`123`丢弃；

二、代码位置：
`components\net\at\src\at_client.c`，如下函数， 当解析到透传数据中存在IPD关键字，就直接break，后面的透传数据被丢弃；

```c
static int at_recv_readline(at_client_t client)
{
    rt_size_t read_len = 0;
    char ch = 0, last_ch = 0;
    rt_bool_t is_full = RT_FALSE;

rt_memset(client->recv_line_buf, 0x00, client->recv_bufsz);
    client->recv_line_len = 0;

while (1)
    {
        at_client_getchar(client, &ch, RT_WAITING_FOREVER);

if (read_len < client->recv_bufsz)
        {
            client->recv_line_buf[read_len++] = ch;
            client->recv_line_len = read_len;
        }
        else
        {
            is_full = RT_TRUE;
        }

/* is newline or URC data */
        if ((ch == '\n' && last_ch == '\r') || (client->end_sign != 0 && ch == client->end_sign)
                || get_urc_obj(client))
        {
            if (is_full)
            {
                LOG_E("read line failed. The line data length is out of buffer size(%d)!", client->recv_bufsz);
                rt_memset(client->recv_line_buf, 0x00, client->recv_bufsz);
                client->recv_line_len = 0;
                return -RT_EFULL;
            }
            break;
        }
        last_ch = ch;
    }

#ifdef AT_PRINT_RAW_CMD
    at_print_raw_cmd("recvline", client->recv_line_buf, read_len);
#endif

return read_len;
}
```