From: Linus Walleij > Sent: 28 June 2019 09:46 ... > A problem with LEDs is that it invites bikeshedding because it is too > relateable. Bikeshedding leds :-) It also isn't at all clear how to handle bi-colour and tri-colour leds. ISTR the usual interface lets you set the brightness, but more often leds are single brightness but multi-colour. Eg the ethernet 'speed' led which is (usually) off/orange/green. Changing the brightness either means changing the current or using PWM. Both really require more hardware support than changing colours. I've done some led driving (for a front panel) from a PLD (small FPGA). As well as the obvious things I did: - dim: 1/8th on at 80Hz. - flash: 1/8th on at 4Hz. - orange: 50-50 red-green at 80Hz on an RGB led. There was also the 'ethernet activity' led which could either be driven by the hardware, or forced on/off/flash by the driver. If driven by the hardware, the software could read the current state. None of this really fitted the Linux leds interface. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
