Raspberry Pi Zero W Onboard LED tie-in with WiFi Lan

I'm using OpenWRT release 19.07.4 on a Raspberry Pi Zero W

root@OpenWrt:~# grep VERSION_ID /etc/os-release 
root@OpenWrt:~# dmesg | grep Raspberry 
[    0.000000] OF: fdt: Machine model: Raspberry Pi Zero W Rev 1.1

opkg upgrades to the latest available updates are in place. extra packages installed are diff, and vim-full.

The ZeroW is just a wireless lan for interconnecting 3 hosts:

  • A laptop
  • Another Pi Zero W
  • A Pi 3

The onboard green LED for the Pi is tied with disk usage, and once startup is complete and the ZeroW is running full steam, the LED turns itself off, and does nothing. So I wanted to repurpose the LED to signal WiFi enablement and traffic.

I can manually control the led by putting the appropriate values into /sys/class/leds/led0/brightness:

# Zero for LED On
root@OpenWrt:~# echo 0 >  /sys/class/leds/led0/brightness 
# Non-Zero for LED off
root@OpenWrt:~# echo 1 >  /sys/class/leds/led0/brightness

However, no matter what combination of options I use to create a trigger for led0, I am unable to repurpose it as a WiFi Status indicator.

What am I missing?

My config :

root@OpenWrt:~# grep -A 10 'config led' /etc/config/system
config led
	option dev 'wlan0'
	option sysfs 'led0'
	option default '1'
	option trigger 'netdev'
	list mode 'link'
	option name 'WiFiStatus'

I have tried both default '0' and default '1', with no change in its state.

root@OpenWrt:~# grep . /sys/class/leds/led0/* 
/sys/class/leds/led0/trigger:none timer default-on input [netdev] mmc1 mmc0