WIFI
1 WIFI Module Overview
The GM-3568JHF development board integrates the RTL8723DU wireless network module, providing complete IEEE 802.11 b/g/n wireless network connectivity. This module connects to the main controller chip via the USB interface and supports wireless communication in the 2.4GHz band, providing flexible wireless network access for the development board.
1.1 RTL8723DU Module Technical Specifications
| Parameter | Specification |
|---|---|
| Chip Model | Realtek RTL8723DU |
| Interface Type | USB 2.0 |
| Wireless Standard | IEEE 802.11 b/g/n |
| Operating Frequency Band | 2.4GHz (2.412~2.484GHz) |
| Transfer Rate | Up to 150Mbps (802.11n) |
| Modulation | OFDM, CCK, BPSK, QPSK, 16-QAM, 64-QAM |
| Antenna Configuration | 1T1R (single transmit, single receive) |
| Transmit Power | Up to 20dBm |
| Receive Sensitivity | -70dBm @ 150Mbps |
| Encryption Support | WEP, WPA/WPA2-PSK, WPA/WPA2-Enterprise |
1.2 Performance Indicators
| Mode | Maximum Rate | Typical Range | Power Consumption |
|---|---|---|---|
| 802.11b | 11Mbps | 100m | Low |
| 802.11g | 54Mbps | 50m | Medium |
| 802.11n | 150Mbps | 30m | Medium-High |
2 WIFI Connection Configuration
The development board uses the RTL8723DU module, and the WIFI driver and related software components are already adapted in the system by default.
2.1 Connecting to WIFI
As shown in the figure, find the network icon in the upper right corner of the system and click it to connect to WIFI 
Use the ifconfig command to view the IP address and other information
root@linaro-alip:/# ifconfig
···
wlx78228877b4a5: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.137.149 netmask 255.255.255.0 broadcast 192.168.137.255
inet6 fe80::d175:3cd1:73ca:ecc8 prefixlen 64 scopeid 0x20<link>
ether 78:22:88:77:b4:a5 txqueuelen 1000 (Ethernet)
RX packets 69 bytes 954099 (931.7 KiB)
RX errors 0 dropped 143 overruns 0 frame 0
TX packets 72 bytes 116372 (113.6 KiB)
TX errors 0 dropped 23 overruns 0 carrier 0 collisions 02.2 Connectivity Test
Execute the following command to view the obtained IP address, and use the ping command to test whether the communication between the development board and the PC is normal. 192.168.49.85 is the actual IP address of the PC. Please ensure that the development board and the PC are in the same local area network.
root@linaro-alip:/# ping 192.168.49.85 -I wlx78228877b4a5 -c 8
ping 192.168.49.85 -I wlx78228877b4a5 -c 8
PING 192.168.49.85 (192.168.49.85) from 192.168.137.149 wlx78228877b4a5: 56(84) bytes of data.
64 bytes from 192.168.49.85: icmp_seq=1 ttl=127 time=5.14 ms
64 bytes from 192.168.49.85: icmp_seq=2 ttl=127 time=3.66 ms
64 bytes from 192.168.49.85: icmp_seq=3 ttl=127 time=2.83 ms
64 bytes from 192.168.49.85: icmp_seq=4 ttl=127 time=2.81 ms
64 bytes from 192.168.49.85: icmp_seq=5 ttl=127 time=9.44 ms
64 bytes from 192.168.49.85: icmp_seq=6 ttl=127 time=2.77 ms
64 bytes from 192.168.49.85: icmp_seq=7 ttl=127 time=3.46 ms
64 bytes from 192.168.49.85: icmp_seq=8 ttl=127 time=3.09 ms
--- 192.168.49.85 ping statistics ---
8 packets transmitted, 8 received, 0% packet loss, time 7011ms
rtt min/avg/max/mdev = 2.771/4.150/9.442/2.128 ms2.3 TCP Bandwidth Test
Use the iperf3 tool to test the network communication bandwidth between the development board and the PC as follows.
Server
Install the iperf3 tool on the development board with network access, and execute the following command:
root@linaro-alip:/# sudo apt update
root@linaro-alip:/# sudo apt install iperf3The development board acts as the server, execute the following command:
root@linaro-alip:/# iperf3 -s
-----------------------------------------------------------
Server listening on 5201 (test #1)
-----------------------------------------------------------Client
The iperf3 tool for Windows can be obtained from the test tool package.
Open PowerShell in Windows, navigate to the path where the iperf3 tool is located. Use Windows as the client to send data, execute the following command:
.\iperf3.exe -c 192.168.137.149 // 192.168.137.149 为服务端 IP 地址2.4 Test Results
Server
root@linaro-alip:/# iperf3 -s
-----------------------------------------------------------
Server listening on 5201 (test #1)
-----------------------------------------------------------
Accepted connection from 192.168.137.1, port 65396
[ 5] local 192.168.137.149 port 5201 connected to 192.168.137.1 port 65397
[ ID] Interval Transfer Bitrate
[ 5] 0.00-1.00 sec 4.88 MBytes 40.9 Mbits/sec
[ 5] 1.00-2.00 sec 5.40 MBytes 45.3 Mbits/sec
[ 5] 2.00-3.00 sec 5.22 MBytes 43.8 Mbits/sec
[ 5] 3.00-4.00 sec 5.36 MBytes 45.0 Mbits/sec
[ 5] 4.00-5.00 sec 5.14 MBytes 43.1 Mbits/sec
[ 5] 5.00-6.00 sec 5.22 MBytes 43.8 Mbits/sec
[ 5] 6.00-7.00 sec 5.40 MBytes 45.3 Mbits/sec
[ 5] 7.00-8.00 sec 5.12 MBytes 43.0 Mbits/sec
[ 5] 8.00-9.00 sec 5.38 MBytes 45.1 Mbits/sec
[ 5] 9.00-10.00 sec 5.24 MBytes 43.9 Mbits/sec
[ 5] 10.00-10.05 sec 266 KBytes 45.9 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate
[ 5] 0.00-10.05 sec 52.6 MBytes 43.9 Mbits/sec receiver
-----------------------------------------------------------Client
3 Command-line WIFI Configuration
3.1 Connecting to WIFI with wpa_supplicant
1) Scan for Available Networks
# 启动 WIFI 接口
sudo ifconfig wlx78228877b4a5 up
# 扫描可用的 WIFI 网络
sudo iwlist wlx78228877b4a5 scan | grep ESSID
# 或使用 iw 命令
sudo iw dev wlx78228877b4a5 scan | grep SSID2) Create the wpa_supplicant Configuration File
# 创建配置文件
sudo nano /etc/wpa_supplicant/wpa_supplicant.conf
# 添加以下内容
ctrl_interface=/var/run/wpa_supplicant
ctrl_interface_group=0
update_config=1
country=CN
# WPA/WPA2-PSK 网络配置
network={
ssid="YourWiFiName"
psk="YourPassword"
key_mgmt=WPA-PSK
priority=1
}
# 开放网络配置
network={
ssid="OpenWiFi"
key_mgmt=NONE
priority=2
}
# WEP 网络配置
network={
ssid="WEPNetwork"
wep_key0="your_wep_key"
key_mgmt=NONE
wep_tx_keyidx=0
}3) Connect to the WIFI Network
# 启动 wpa_supplicant
sudo wpa_supplicant -B -i wlx78228877b4a5 -c /etc/wpa_supplicant/wpa_supplicant.conf
# 获取 IP 地址
sudo dhclient wlx78228877b4a5
# 检查连接状态
wpa_cli -i wlx78228877b4a5 status3.2 Managing WIFI with NetworkManager
Command-line tool nmcli
# 查看 WIFI 状态
nmcli radio wifi
# 扫描 WIFI 网络
nmcli dev wifi list
# 连接 WIFI 网络
nmcli dev wifi connect "SSID" password "PASSWORD"
# 查看已保存的连接
nmcli connection show
# 断开 WIFI 连接
nmcli dev disconnect wlx78228877b4a5
# 删除已保存的连接
nmcli connection delete "SSID"4 WIFI Hotspot Mode (AP Mode)
4.1 Install hostapd
sudo apt-get update
sudo apt-get install hostapd dnsmasq4.2 Configure hostapd
# 创建 hostapd 配置文件
sudo nano /etc/hostapd/hostapd.conf
# 添加以下内容
interface=wlx78228877b4a5
driver=nl80211
ssid=GM-3568JHF-AP
hw_mode=g
channel=7
wmm_enabled=0
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=12345678
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP4.3 Configure the DHCP Service
# 备份原配置
sudo cp /etc/dnsmasq.conf /etc/dnsmasq.conf.backup
# 编辑 dnsmasq 配置
sudo nano /etc/dnsmasq.conf
# 添加以下内容
interface=wlx78228877b4a5
dhcp-range=192.168.4.2,192.168.4.20,255.255.255.0,24h4.4 Configure the Network Interface
# 设置静态 IP
sudo ifconfig wlx78228877b4a5 192.168.4.1 netmask 255.255.255.0
# 启用 IP 转发
echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward
# 配置 NAT 规则
sudo iptables -t nat -A POSTROUTING -o end0 -j MASQUERADE
sudo iptables -A FORWARD -i end0 -o wlx78228877b4a5 -m state --state RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A FORWARD -i wlx78228877b4a5 -o end0 -j ACCEPT4.5 Start the Hotspot Service
# 启动 hostapd
sudo hostapd /etc/hostapd/hostapd.conf &
# 启动 dnsmasq
sudo systemctl start dnsmasq
# 检查服务状态
sudo systemctl status hostapd
sudo systemctl status dnsmasq5 Troubleshooting
1) WIFI Module Cannot Be Recognized
Inspection Steps:
# 检查 USB 设备
lsusb | grep Realtek
# 检查内核模块
lsmod | grep rtl
# 手动加载驱动
sudo modprobe rtl8xxxu
# 检查固件文件
ls /lib/firmware/rtlwifi/2) Cannot Connect to WIFI Network
Possible Causes and Solutions:
# 检查网络接口状态
ip link show wlx78228877b4a5
# 重启网络接口
sudo ifconfig wlx78228877b4a5 down
sudo ifconfig wlx78228877b4a5 up
# 检查 wpa_supplicant 日志
sudo journalctl -u wpa_supplicant
# 重新配置网络
sudo wpa_cli -i wlx78228877b4a5 reconfigure3) Weak Signal or Unstable Connection
Optimization Suggestions:
# 检查信号强度
iwconfig wlx78228877b4a5 | grep "Signal level"
# 扫描信道使用情况
sudo iwlist wlx78228877b4a5 scan | grep Frequency
# 更换信道（AP 模式）
sudo iwconfig wlx78228877b4a5 channel 6
# 调整发射功率
sudo iwconfig wlx78228877b4a5 txpower 204) Slow Network Speed
Diagnosis and Optimization:
# 检查当前连接速率
iwconfig wlx78228877b4a5 | grep "Bit Rate"
# 检查网络拥塞
ping -c 10 8.8.8.8
# 使用 iperf3 测试带宽
iperf3 -c speedtest.server.com
# 优化 TCP 窗口大小
echo 'net.core.rmem_max = 16777216' >> /etc/sysctl.conf
echo 'net.core.wmem_max = 16777216' >> /etc/sysctl.conf5) Hotspot Mode Issues
Common Issue Resolution:
# 检查 hostapd 状态
sudo systemctl status hostapd
# 查看 hostapd 日志
sudo journalctl -u hostapd
# 检查防火墙设置
sudo iptables -L
# 重启相关服务
sudo systemctl restart hostapd
sudo systemctl restart dnsmasq