WiFi (wlan0) Setup

How to enable WiFi on the CanMV K230 and connect to an access point.

Prerequisites

• Board is booted and serial console is accessible
• Target WiFi network uses 2.4GHz band (K230 does not support 5GHz)

2.4GHz only

The K230 WiFi chip (bcmdhd) only supports 2.4GHz (ch1-13). It cannot connect to 5GHz SSIDs.

1. Check Initial State

By default, wlan0 exists but is DOWN and does not appear in ifconfig (without -a).

Inspection Commands

expect -c '
  log_user 1
  set timeout 10
  set serial [open /dev/ttyACM0 r+]
  fconfigure $serial -mode 115200,n,8,1 -translation binary -buffering none
  spawn -open $serial

  send "\r"
  expect "]#"

  send "ifconfig -a\r"
  expect "]#"

  send "ip link show wlan0\r"
  expect "]#"

  send "lsmod\r"
  expect "]#"

  send "ps | grep wpa_supplicant\r"
  expect "]#"

  send "cat /etc/network/interfaces\r"
  expect "]#"

  send "cat /etc/wpa_supplicant.conf\r"
  expect "]#"
'

Default State

Item	Status
wlan0	Exists but DOWN (qdisc noop)
bcmdhd driver	Loaded
wpa_supplicant	Not running
/etc/network/interfaces	Only lo and eth0
/etc/wpa_supplicant.conf	key_mgmt=NONE, no SSID configured

2. Edit Configuration Files

/etc/wpa_supplicant.conf

Use wpa_passphrase to hash the password:

# Create header
cat > /etc/wpa_supplicant.conf << 'EOF'
ctrl_interface=/var/run/wpa_supplicant
ap_scan=1
EOF

# Generate hashed PSK and append (exclude plaintext line)
wpa_passphrase "YourSSID" "YourPassword" | grep -v '#psk=' >> /etc/wpa_supplicant.conf

# Verify
cat /etc/wpa_supplicant.conf

Result:

ctrl_interface=/var/run/wpa_supplicant
ap_scan=1

network={
    ssid="YourSSID"
    psk=abcdef1234567890...    <- 256-bit hashed PSK
}

About wpa_passphrase

wpa_passphrase generates the PSK from the SSID + password combination. If you change the SSID, you must regenerate the PSK.

/etc/network/interfaces

Add auto-start configuration for wlan0.

Run on the K230 serial console:

cat > /etc/network/interfaces << 'EOF'
# interface file auto-generated by buildroot

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

auto wlan0
iface wlan0 inet dhcp
  pre-up wpa_supplicant -B -i wlan0 -c /etc/wpa_supplicant.conf
  post-down killall -q wpa_supplicant
EOF

3. Start WiFi

ifup wlan0

The /etc/network/interfaces configuration automatically:

1. Starts wpa_supplicant and connects to the WiFi AP
2. Obtains an IP address via DHCP

Verify Connection

# WPA connection state (should show COMPLETED)
wpa_cli -i wlan0 status

# Check for IP address
ifconfig wlan0

# Test internet connectivity
ping -c 3 8.8.8.8

4. Troubleshooting

AP Not Found (stuck on SCANNING)

# List detected APs
iwlist wlan0 scan 2>&1 | head -30

# Check supported frequencies
iwlist wlan0 frequency 2>&1

The WLAN on the CanMV K230 only supports 2.4GHz. Make sure you are not using a 5GHz SSID.

Buffalo routers

SSID Pattern	Band	K230 Support
Buffalo-A-xxxx	5GHz	Not supported
Buffalo-G-xxxx	2.4GHz	Supported

4-Way Handshake Failure (DEAUTH reason 15)

dmesg | grep -iE "assoc|auth|4way|eapol|reason|handshake" | tail -20

If WLC_E_DEAUTH_IND reason 15 appears, the PSK is incorrect.

Common causes:

• Password typo
• SSID was changed but PSK was not regenerated (wpa_passphrase output depends on the SSID)

Fix:

cat > /etc/wpa_supplicant.conf << 'EOF'
ctrl_interface=/var/run/wpa_supplicant
ap_scan=1
EOF

# Regenerate PSK with the correct SSID
wpa_passphrase "YourSSID" "YourPassword" | grep -v '#psk=' >> /etc/wpa_supplicant.conf

# Restart WiFi
ifdown wlan0
ifup wlan0

# Verify
wpa_cli -i wlan0 status
ifconfig wlan0
ping -c 3 8.8.8.8

No Auto-Connect After Reboot

Verify that /etc/network/interfaces contains auto wlan0. The init script /etc/init.d/S40network runs ifup -a at boot, so auto wlan0 ensures WiFi starts automatically.

Debug Logs

# Detailed wpa_supplicant log
wpa_supplicant -i wlan0 -c /etc/wpa_supplicant.conf -d

# WiFi-related dmesg
dmesg | grep -i -E "wifi|wlan|wireless|sdio|mmc|cfg80211|bcmdhd"