Wi-Fi R-Mesh Programming Guide

Example

This section demonstrates how to establish an R-Mesh network and achieve data communication between nodes. This example will help you become familiar with the basic usage of R-Mesh.

1. Obtain the SDK

   SDK download: IoT SDK

   Note

   By default, the root node in SDK supports only 2 connections. To enable more connections, please follow these steps:

   1. Obtain the R-Mesh WLAN library (contact us)

   2. Replace lib_wifi_whc_ap.a at {sdk}/amebaxxx_gcc_project/project_km4/asdk/lib/application

   3. Replace lib_wifi_common.a, lib_wifi_fw.a, and lib_wifi_whc_np.a at {sdk}/amebaxxx_gcc_project/project_km0/asdk/lib/application

2. Enable R-MESH Feature

   Open the Wi-Fi configuration file {sdk}/component/soc/usrcfg/amebaxxx/ameba_wificfg.c and set the following parameter:

   wifi_user_config.wtn_en = 1;
   

   For additional settings, please refer to Programming Interface

3. Enable R-MESH NAT Feature

   Note

   Skip this step if RNAT functionality is not required.

   1. Open the Wi-Fi configuration file {sdk}/component/soc/usrcfg/amebaxxx/ameba_wificfg.c and set the following parameter:

      wifi_user_config.wtn_rnat_en = 1;
      

   2. To designate the node as a permanent RNAT node, set this parameter (required in current version as automatic RNAT selection is under development):

      wifi_user_config.wtn_fixed_rnat_node = 1;
      

   3. Execute ./menuconfig.py in {sdk}/amebadxxx_gcc_project and select CONFIG LWIP > Enable NAT REPEATER:

      ----Connectivity config----
      CONFIG WHC INTF  --->
      ...
      CONFIG LWIP  --->
         [ ] Enable Fast DHCP
         [*] Enable NAT REPEATER
         [*] Enable LWIP NETCONN SEM PER THREAD
         [ ] Enable LWIP Debug
      ...
      

      For additional RNAT settings, please refer to RNAT Parameters

4. Compilation and Flashing

   Please refer to standard compilation procedures: gcc_build_environment

5. Visualization Tool (Gravitation)

   To visually display R-Mesh node topology, we provide the Gravitation tool. Please refer to Gravitation for configuration.

6. Join the Network

   • Method 1: Use ATCMD to add all nodes to the network.

     Example:

     AT+WLCONN=ssid,rmesh_test,pw,12345678
     

   • Method 2: Use RPP (R-mesh Provision Protocol) to join network (coming soon)

7. Topology Display

   After joining the network, nodes automatically send information to the Gravitation tool. The following figure shows 4 nodes successfully connected to the AP.

   Basic information appears above each node is: MAC_Addr[5]:IP(update_time).

   Example: The node in the top-left corner shows: 1A:192.168.2.102(2:26) which means:

   • MAC Address: XX:XX:XX:XX:0x1A

   • IP Address: 192.168.2.102

   

   For more details, please refer to Gravitation .

   Note

   While the tool displays node connection relationships, it cannot reflect physical locations. You may:

   1. Disable Auto Layout in the bottom-right corner

   2. Manually drag nodes to match their real-world positions

8. Switch Verification

   To verify switch behavior:

   1. Physically move two nodes away from the AP (e.g., node 62 and node 6D shown on the right)

   2. Observe that node 6D automatically switches its connection to node 62 when AP’s RSSI is worse than node 62

   

9. Communication Verification

   • Method 1: Execute the Ping command on any node

     Ping Test Example:

     AT+PING=192.168.2.102
     

   • Method 2: Use Gravitation Tool’s Ping Test Function

     The tool conveniently initiates ping tests for all nodes:

     

     Ping log appears above each node is: Ping: Successful packets/Failed packets - Packet loss rate/RTT

     Example: The node in the down-left corner shows: P:29/2-6.5%/20 which means:

     • 29 successful packets

     • 2 failed packets

     • 6.5% packet loss rate

     • RTT of 20 ms

Programming Interface

Common

User Configuration File

Path: {sdk}/component/soc/usrcfg/amebaxxx/ameba_wificfg.c

Parameter	Description
wtn_en	R-Mesh enable. Set to 1 to activate
wtn_strong_rssi_thresh	Node directly connects to AP if detected RSSI exceeds this threshold
wtn_father_refresh_timeout	Child node switches parent if no beacon received within this period (in ms)
wtn_child_refresh_timeout	Parent node removes child if no beacon received within this period (in ms)
wtn_max_node_num	Max nodes in R-Mesh network. Determines beacon window size: higher node count reduces window size and increases interval

RNAT Parameters

User Configuration File

Path: {sdk}/component/soc/usrcfg/amebaxxx/ameba_wificfg.c

Parameter	Description
wtn_rnat_en	R-Mesh NAT enable. Set to 1 to activate.
wtn_fixed_rnat_node	Force device as R-NAT node. Set to 1 to enable (effective only when wifi_user_config.wtn_rnat_en=1)
wtn_connect_only_to_rnat	Connect only to RNAT or its child nodes as parent. Set to 1 to enable
ap_sta_num	Max child nodes connectable when acting as RNAT. Currently supports up to 14 clients

Note

When wifi_user_config.ap_sta_num > 5, adjust memory layout as follows:

Open {sdk}/amebadplus_gcc_project/amebaDplus_layout.ld and modify RAM_KM0_IMG2_SIZE from 96K to 116K to support 14 direct clients.

#define RAM_KM0_IMG2_SIZE                KBYTES(116)

RNAT menuconfig

Execute ./menuconfig.py in {sdk}/amebaxxx_gcc_project, then select: CONFIG LWIP ‣ Enable NAT REPEATER

----Connectivity config----
CONFIG WHC INTF  --->
...
CONFIG LWIP  --->
   [ ] Enable Fast DHCP
   [*] Enable NAT REPEATER
   [*] Enable LWIP NETCONN SEM PER THREAD
   [ ] Enable LWIP Debug
...