LEDs on Red with WP77xx


Does anyone know if there’s a way to access any of the side LEDs (D200, D401, or D402) from an application? From looking through the schematic, I suspect the answer is no, but I’m far from an expert.

I’m using a WP7702, and from reading other posts it looks like the usual application LED (D410) isn’t accessible from a WP77xx, but it would be really disappointing if there wasn’t any LED that could be used for things like BLE device registration, backend registration, etc.

Thanks in advance,


LED D401 can be user controlled. LED driver provides access to this gpio is in sysfs:


Thanks asyal. I managed to get it working.

For any fellow newbies that stumble on this short thread with a similar issue, I’ll give some detail on how I got this working. I don’t know that this is the most efficient way to do it, but I see D401 blinking on the Red on my desk, and that’s good enough for me, for now.

  1. D401 is connected to the GPIO expander, not to the CF3 socket directly, so you’ll need to enable the GpioExpanderService to access it. Uncomment the GpioExpanderService in the main .sdef file, and rebuild. Update, and use ‘app status’ to check that gpioExpanderServiceRed is running.
  2. You can use the code from gpioPin.c in the gpioExpanderDemo source for configuring, activating, and deactivating the LED. The only one you care about is LEDCardDetect0.
  3. Make sure you have “mangoh_ledCardDetect0Gpio = le_gpio.api” in the api section of your .cdef file, and “xxx.xxxComponent.mangoh_ledCardDetect0Gpio -> .mangoh_gpioExpPin8”. You can obviously rename ledCardDetect0Gpio across your app and config files, but I just left it as is from the demo code.
  4. Build and do your update, and start your app if necessary. Use ‘sdir list’ to make sure your bindings are OK. This tool really doesn’t get enough of the limelight; most of my dumb problems are binding-related, and it’s helped me climb out of several holes I’ve dug for myself.

Hope this helps someone in the future, and thanks again to asyal for pointing me in the right direction.