Merge pull request #12 from shaoguoji/add_spi_retry

[fix]修复内存访问bug，延时确保初始化稳定性

example/rw007_stm32_port.c

@@ -51,6 +51,7 @@ int wifi_spi_device_init(void)
     rt_wlan_set_mode(RT_WLAN_DEVICE_STA_NAME, RT_WLAN_STATION);
     rt_wlan_set_mode(RT_WLAN_DEVICE_AP_NAME, RT_WLAN_AP);
     
+    rt_thread_mdelay(2000);
     rw007_sn_get(sn_version);
     rt_kprintf("\nrw007  sn: [%s]\n", sn_version);
     rw007_version_get(sn_version);

src/spi_wifi_rw007.c

@@ -201,7 +201,7 @@ _exit:
     rt_spi_release_bus(rt_spi_device);
 
     /* Free send data space */
-    if (data_packet)
+    if (data_packet && !pre_data_packet)
     {
         rt_mp_free((void *)data_packet);
         data_packet = RT_NULL;