NXP Application Code Hub

Near and Far Motion Detection using Wi-Fi CSI on FRDM i.MX 91 + IW610

The Near and Far Motion Detection demo updates a webpage with real-time CSI-based motion detection between the DUT (STA) and external AP.

Boards: FRDM-IMX91

Categories: Networking, Wireless Connectivity, Security

Peripherals: Wi-Fi

Toolchains: GCC

Table of Contents

1. Software
2. Hardware
3. Setup
4. Results
5. FAQs
6. Support
7. Release Notes

1. Software

• Linux-BSP for FRDM-i.MX91
• Wireless utilities and example images

2. Hardware

• FRDM-i.MX91
• Ublox Maya-W476

3. Setup

3.1 Pre-Requisites/Requirements

1. FRDM i.MX91 Development Board (DUT)
2. External Access Point (Ex-AP / Router)
3. Mobile phone or laptop to connect to DUT-AP (uap0)
4. Mobile phone or laptop to initiate communication from Ex-AP backend to DUT-STA (mlan0)
5. Download the Wireless-Utilities-and-example-Images.zip package from the Wireless utilities and example image link.
6. Put the mlancsi utility in the csi_webserver directory from the Wireless-Utilities-and-example-Images.zip package.
7. Create the config directory in the csi_webserver directory and put the config files in the config directory from the Wireless-Utilities-and-example-Images.zip package.
8. Put example images in the csi_webserver directory from the Wireless-Utilities-and-example-Images.zip package.

3.2 Steps

1. Flash BSP

   • Download Linux BSP for FRDM-i.MX91 from the link mentioned in Software section.
   • Power ON DUT and flash the downloaded Linux BSP.

2. Deploy Application

   • Copy "csi_webserver" directory on DUT.
   • Enter to the directory

   # cd csi_webserver 
   

   • Make the utilitis and script executable.

   # chmod +x mlancsi board_load_secure.sh test_csi_conference.sh
   

3. Update Ex-AP Credentials in Configuration File:

   • Update the existing SSID and password with those of the Ex-AP that DUT-STA should connect to.

4. Configure DUT

Run the script:

# ./board_load_secure.sh

This script will perform below configurations:

• Load driver and firmware
• Enable STA mode(mlan0) and connect to Ex-AP
• Obtain dynamic IP for mlan0 via udhcpc
• Assign static IP 192.168.4.1 to uap0 and enable DUT-AP (uap0)

5. Connect Mobile Device
   • Connect to DUT-AP (uap0); Mobile device gets dynamic IP in 192.168.4.xx range.
   • If mobile fails to connect to DUT-AP, set static IP from advanced network settings.
6. Update Configurations
   • config/csi.conf:
     • The default packet type is set as HE 20 MHz, so the AP must support 802.11ax.
     • Update Ex-AP MAC
     • Update Channel - The channel value must be provided in hex format. For example, channel 36 should be set as 24.
     • Update Band settings - Band 00: 2.4GHz, Band 01: 5GHz.
   • config/mlancsi.conf: Update Ex-AP MAC
7. Verify Connectivity
   • DUT-STA (mlan0) ↔ Ex-AP
   • DUT-AP (uap0) ↔ Mobile device
   • IPs assigned to both interfaces
8. Backend Communication
   • Connect another device (Mobile/laptop) to Ex-AP and ping DUT-STA from it.
9. Run CSI Test

# ./test_csi_conference.sh

This script will perform below configurations:

• Start web server on 192.168.4.1
• Monitor real-time CSI data
• The webpage updates with corresponding motion-detection images based on the predefined CSI range.

10. From the mobile device connected to the EX-AP (backend), initiate data communication to DUT-STA (mlan0) using ping. The ping interval must be set as >=0.5 seconds to get the accurate motion detection.

11. From the mobile device connected to the DUT-AP (uap0), open any web browser and enter "http://192.168.4.1" in the address bar to access the hosted webpage.

3.3 Notes

• uap0 must use static IP 192.168.4.1 (mandatory for web hosting).
• PACKET_TYPE in mlancsi.conf may vary depending on Ex-AP; configure accordingly to collect AMI values.

4. Results

Once the scripts are executed, you can observe multiple logs on the DUT console. Below is the breakdown:

• After running ./board_load_secure.sh Displays DUT interface details (STA & AP configuration):

    phy#0
        Interface wfd0
                ifindex 6
                wdev 0x3
                addr ba:f4:4f:ab:43:61
                type managed
                txpower 8.00 dBm
        Interface uap0
                ifindex 5
                wdev 0x2
                addr ba:f4:4f:ab:44:61
                ssid NXP_WiFi_AP
                type AP
                channel 36 (5180 MHz), width: 20 MHz, center1: 5180 MHz
                txpower 8.00 dBm
        Interface mlan0
                ifindex 4
                wdev 0x1
                addr b8:f4:4f:ab:43:61
                ssid ASUS_5G
                type managed
                channel 36 (5180 MHz), width: 20 MHz, center1: 5180 MHz
                txpower 8.00 dBm

• After executing ./test_csi_conference.sh, Logs confirming webserver startup:

Serving HTTP on 192.168.4.1 port 80 (http://192.168.4.1:80/) ...
192.168.4.2 - - [29/May/2025 23:13:23] "GET /current.png?t=1774595418940 HTTP/1.1" 200 -

• CSI Monitoring Initialized

---------------------------------------------------
------- NXP Wifi CSI Processing app v1.2 ------
---------------------------------------------------

[INFO] Initializing App
00 01 02 03
00 01 02 03
aa
01
24
00
01
00
01
Found 9 bytes in the csifilter0 section of conf file config/csi.conf.
7c 10 c9 02 da 4c 02 08 00
Found -1 bytes in the csifilter1 section of conf file config/csi.conf.
Expected filter size is 9
Found 1 CSI filters
awk: cmd. line:1: (FILENAME=- FNR=1) fatal: attempt to access field -1
CSI Value:
awk: cmd. line:1: (FILENAME=- FNR=1) fatal: attempt to access field -1
CSI Value:
192.168.4.2 - - [29/May/2025 23:13:25] "GET /current.png?t=1774595420937 HTTP/1.1" 200 -
CSI Value: ---------------------------------------------------
192.168.4.2 - - [29/May/2025 23:13:26] "GET / HTTP/1.1" 304 -
CSI Value: v1.2
192.168.4.2 - - [29/May/2025 23:13:26] "GET /current.png HTTP/1.1" 200 -
CSI Value: ---------------------------------------------------
awk: cmd. line:1: (FILENAME=- FNR=1) fatal: attempt to access field -1
CSI Value:
CSI Value: Initializing
CSI Value: file
192.168.4.2 - - [29/May/2025 23:13:28] "GET /current.png?t=1774595424018 HTTP/1.1" 200 -
CSI Value: CSI_EVENT_CFG
CSI Value: MAC_ADDR=7c:10:c9:02:da:4c
CSI Value: PACKET_TYPE=3
192.168.4.2 - - [29/May/2025 23:13:30] "GET /current.png?t=1774595426013 HTTP/1.1" 200 -
CSI Value: FORMAT_BW=0
CSI Value: UPDATE_REF=1
CSI Value: IIR_ALPHA=0.100000
CSI Value: KALMAN_P0=0.500000
192.168.4.2 - - [29/May/2025 23:13:32] "GET /current.png?t=1774595428015 HTTP/1.1" 200 -
CSI Value: KALMAN_ALPHA=0.005000
CSI Value: KALMAN_N0=0.200000
CSI Value: NUM_CSI=0

• Motion Detection & Image Update

CSI Value: -7.6
Near motion detected
CSI Value: -7.2
Near motion detected
CSI Value: -7.7
Near motion detected
192.168.4.2 - - [29/May/2025 23:13:36] "GET /current.png?t=1774595432014 HTTP/1.1" 200 -
CSI Value: -8.6
Near motion detected
CSI Value: -11.2
Near motion detected
192.168.4.2 - - [29/May/2025 23:13:38] "GET /current.png?t=1762516461560 HTTP/1.1" 200 -
CSI Value: -12.1
Far motion detected
192.168.4.2 - - [29/May/2025 23:13:40] "GET /current.png?t=1762516462559 HTTP/1.1" 200 -
CSI Value: -13.2
Far motion detected

5. FAQs

Include FAQs here if appropriate. If there are none, then remove this section.

6. Support

Provide URLs for help here.

Project Metadata

Questions regarding the content/correctness of this example can be entered as Issues within this GitHub repository.

Warning: For more general technical questions regarding NXP Microcontrollers and the difference in expected functionality, enter your questions on the NXP Community Forum

7. Release Notes

Version	Description / Update	Date
1.1	Initial release on Application Code Hub	March 25th 2026