5 【求助】LAN8720 ping成功一次后，再次ping就失败了？？？

发布于 2025-01-05 18:27:20 浏览：116 订阅该版

[tocm]

# 🔧硬件配置：
STM32F407ZGT6【[来自反客科技](https://item.taobao.com/item.htm?abbucket=9&id=588438707815&ns=1&pisk=gfur311aXULPVugyKS4F7gjTzMU8yzv6z2wQtXc3N82uFXV38xDBw8GHevuUnXnWwk9RT_3qQw_We3hh8yaHCdT65bd8Jyv6Q0E9tTFas9YQEgb0yWZJhI6X5bh8J_WH1mY1LHm9-Tj3Kv40mWP_-7ql-oA4O7bu-8qhniVgnJ4nKkq0m5V1xJqlrjA417Xh-8bhnjVgZ7joKyAqi-FnORgnzZyzqB0V6Z3P95rzIb2V7j34ZEewW-bH7qVrgRckvwbnu7ro8U_ZdAESxfEtPjTFkzGZmrVrKFvuofmq1uuyQawKe2rI-o5HEurUUm0u06bnNzi-dDkyUgeoVxrTiofeWSM_nb3o0BBmZAwzrSqXSCl0xmg8X49czPmtNzinnE7rIgkPpSDIi2dotMruMSy6gI5HGtMqnU3ccMILmIF4CCRNvMEuMSy6gISdvom4gROw_&priceTId=2147803817360702695017221ed569&skuId=5380733883693&spm=a21n57.1.hoverItem.2&utparam=%7B%22aplus_abtest%22%3A%2275506a90d0df90856b255283003d3a89%22%7D&xxc=taobaoSearch "来自反客科技")】
LAN8720模块【[模块](https://detail.tmall.com/item.htm?_u=535lqpibab72&id=735485301719&pisk=gc9Sz3VaPz45mkUDq4nV5g3Nge6I0eMZpkspjHezvTBROJKy5MyFTbjQdZttqalnZeOXJEfPyw5FdMTNo3yEq3oIdHKOy9RPzML2REVyzp7euvtM5_yyvprkiF-TULllLJ6lK93Z7AkZq3Xhpoaq-E4uMgSiLzBLeTXY7aZr6Akwqn6hpVuZQLld0WSa9JLdwsQA4ZIRJgeKctIO29eR98FYkZjdp9QRyZEAqMeLyJLLkZINXyFRy9BYkMS5pwLdpmtx_ywfvbs9V0Z1usAuSNtRlJepevf553FUdJ9f2_9p2Zt20Ks5NNCqdMHveE-pULfmtWWH0CTB9EHbFetJ6eQyHVeC8CvkDK5_vJC6lM1OpsZLpn6VzFSVBAUfmIKy9LY7AJIkUd5CSsiLK6WvQ1d9PkmMDTIp-1vES8bJvhvM_OMQHT1d4AwN5yo8OSHgdi_ZcmN3tOYUEhK7NLCGwijS7mibrWfRmi_ZcmN3t_IcVdnjczVh.&spm=a1z09.2.0.0.7d812e8dtzB79i "模块")】

# 🧾软件环境：
RT-Thread Studio [2.2.9]
rt-thread [4.1.1]

# 🧷软件包配置：
**打开lwIP和SAL**
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20250105/6f9459123e5a3d9bacac5b27a0d9bcff.png.webp)
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20250105/c75e49a1a8f154c2113271b73b592a0a.png.webp)
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20250105/06f0768781de26fa3591b4dd876e91ff.png.webp)
**只做了如下修改**
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20250105/c0813739cb561e287b7254787b2806ce.png.webp)

# 💡目前测试：
额外添加复位程序
```c
// 定义的复位引脚
#define RESET_IO GET_PIN(C, 6)

/**
 * @brief phy复位引脚初始化
 */
void phy_reset(void)
{
    rt_pin_mode(RESET_IO, PIN_MODE_OUTPUT);

rt_pin_write(RESET_IO, PIN_HIGH);
    rt_thread_mdelay(50);
    rt_pin_write(RESET_IO, PIN_LOW);
    rt_thread_mdelay(50);
    rt_pin_write(RESET_IO, PIN_HIGH);
}
```
模块并没有引出复位引脚，而是靠 RC 上电复位。
模块资料中电路图如下
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20250105/72f27e1b39a9788ae1e1658ef20beaa6.png.webp)
自行更改电路
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20250105/60df29a28a93cbeebe1afbd2c93f7939.png.webp)
用万用表测试上面实物图红框中的RC电路是符合原理图的电气连接的，但是LAN8720芯片的15引脚并没有连接到电阻或电容任何一端。
于是修改电路，示意图如下图
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20250105/c8214c1db1d595014a1a1b92e076d0e1.png.webp)
**程序和硬件修改完毕**

**电脑端IP配置如下**
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20250105/b4287b1aec89728a30cc8d97d624a25b.png.webp)

期间也更换过电脑和网线，现象是一样的。

# 📝日志：
**电脑端 → ping → STM32**
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20250105/48f59d9b70c75c3d7f42cb013ddfc736.png)
**STM32 → ping → 电脑端**
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20250105/b82f18e4b840b5ea25d60cee227a2649.png.webp)

# ❓问题总结：
🤦‍♂️为什么板子ping电脑端只能成功ping一次呢？？电脑端ping板子一直是ping不通的。还请各位大佬指点一下。